The Occurrence of the Rat Lungworm, Angiostrongylus cantonensis, in Nonindigenous Snails in the Gulf of Mexico Region of the United States by John L. Teem PhD; Yvonne Qvarnstrom PhD; Henry S. Bishop BS; Alexandre J. da Silva PhD; Jacoby Carter PhD; Jodi White-Mclean PhD; and Trevor Smith PhD, Hawai‘i Journal of Medicine & Public Health, June 2013, Vol 72, No 6, Supplement 2, June 2013.
Abstract. Nonindigenous apple snails, Pomacea maculata, are currently spreading rapidly through the southeastern United States. This mollusk serves as an intermediate host of the rat lungworm parasite (Angiostrongylus cantonensis), which can cause eosinophilic meningitis in humans who consume infected mollusks. A PCR-based detection assay was used to test nonindigenous apple snails for the rat lungworm parasite in Louisiana, Texas, Mississippi, and Florida. Only apple snails obtained from the New Orleans, Louisiana, area tested positive for the parasite. These results provide the first evidence that Angiostrongylus cantonensis does occur in nonindigenous apple snails in the southeastern United States. Additionally, Angiostrongylus cantonensis was identified in the terrestrial species Achatina fulica in Miami, Florida, indicating that rat lungworm is now established in Florida as well as Louisiana. Although the study suggests that the rat lungworm is not widespread in the Gulf States region, the infected snail population could still pose a risk to human health and facilitate the spread of the parasite to new areas.
The Apple Snail Pomacea canaliculata, a Novel Vector of the Rat Lungworm, Angiostrongylus cantonensis: its Introduction, Spread, and Control in China by Ting-Bao Yang PhD; Zhong-Dao Wu MD, PhD; and Zhao-Rong Lun PhD, Hawai‘i Journal of Medicine & Public Health, June 2013, Vol 72, No 6, Supplement 2, June 2013.
Abstract. The freshwater apple snail Pomacea canaliculata was introduced to Taiwan then to mainland China in the early 1980s from Argentina, its native region, for the purpose of aquaculture. Because of the lack of natural enemies and its tolerance of a wide range of environmental conditions, both its abundance and distribution have dramatically increased and it has become a harmful species to local agriculture and other native species in many areas of China. Unfortunately, the snail also acts as an intermediate host of Angiostrongylus cantonensis, and has been implicated in transfer of the parasite to people, resulting in angiostrongyliasis manifested as eosinophilic meningitis. Efforts to prevent its further spread and population expansion were initiated many years ago, including the use of chemicals and biological control agents to control the snail.
Angiostrongylus cantonensis and Rat Lungworm Disease in Brazil by Silvana Carvalho Thiengo PhD; Raquel de Oliveira Simões MsC; Monica Ammon Fernandez PhD; and Arnaldo Maldonado Júnior PhD, Hawai‘i Journal of Medicine & Public Health, June 2013, Vol 72, No 6, Supplement 2, June 2013.
Abstract. The metastrongyloid nematode genus Angiostrongylus includes 18 species, two of which are relevant from a medical standpoint, Angiostrongylus costaricensis and Angiostrongylus cantonensis. The first was described from Costa Rica in 1971 and causes abdominal angiostrongyliasis in the Americas, including in Brazil. Angiostrongylus cantonensis, first described in 1935 from Canton, China, is the causative agent of eosinophilic meningitis. The natural definitive hosts are rodents, and molluscs are the intermediate hosts. Paratenic or carrier hosts include crabs, freshwater shrimp, amphibians, flatworms, and fish. Humans become infected accidentally by ingestion of intermediate or paratenic hosts and the parasite does not complete the life cycle as it does in rats. Worms in the brain cause eosinophilic meningitis. This zoonosis, widespread in Southeast Asia and the Pacific islands, has now been reported from other regions. In the Americas there are records from the United States, Cuba, Jamaica, Brazil, Ecuador, and Haiti. In Brazil seven human cases have been reported since 2007 from the southeastern and northeastern regions. Epidemiological studies found infected specimens of Rattus norvegicus and Rattus rattus as well as many species of molluscs, including the giant African land snail, Achatina fulica, from various regions of Brazil. The spread of angiostrongyliasis is currently a matter of concern in Brazil.
The aquarium trade as a potential source of fish introductions in southwestern Europe by Alberto Maceda-Veiga, Josep Escribano-Alacid, Adolfo de Sostoa, and Emili García-Berthou, Biological Invasions, May 9, 2013
Abstract. The aquarium trade has been identified as an important vector of aquatic invasive species but this question has mostly been investigated in North America. We investigated the variation in diversity and species composition in different trade types in southwestern Europe (three major international wholesalers, different retail store types, and local internet forums), mostly in Spain and Portugal. As in previous studies, the diversity of fishes in the aquarium trade was vast, with a total of 20 orders, 79 families, and 1,133 fish species detected in the trade types analyzed. 248 species were observed in a single metropolitan area (Barcelona), with estimates of about 294 species being present. International wholesalers had higher species richness and evenness, with a single one having over 700 species. General pet stores had much lower evenness but due to high turnover had a total richness of over 200 species. Internet forums had the lowest evenness but similar richness. The different commerce types varied significantly in relative species abundance with about a dozen of popular fish species (e.g., goldfish, Siamese fighting fish, common carp, guppy, swordtails) dominating the retail stores, particularly the general pet stores. Our results imply that frequency in the trade varies strongly among species and commerce types and although general pet stores have usually low diversity, this is compensated with a higher species turnover. Many of the most popular species are well known invasive species and some of the species available are temperate species that might establish in Europe. For instance, the island apple snail (Pomacea insularum) has established the first European population in the Ebro delta since 2009, when it appeared in a canal adjacent to an aquarium fish farm, and will likely invade the rest of Europe from there (López et al. 2010 ). Such events reinforce the need for more careful implementation of education programs, regulation and monitoring of trade, and internalization of environmental costs by the industry.
The survey of the natural epidemic foci of Angiostrongylus cantonensis in Beihai City of Guangxi, China by XIE Ping*, WU De-ren, Beihai Center for Disease Control and Prevention, Beihai 536000, China, International Journal of Medical Parasitic Diseases, 2013 40 (2): 67-70
Abstract. The objective was to reveal the distribution of Angiostrongylus cantonensis in Beihai City of Guangxi, thus to provide scientific basis for the prevention and control of angiostrongyliasis. Wengshan Village in Haicheng District of Beihai City was selected for the investigation. The hosts of Angiostrongylus cantonensis in the field, markets, and restaurants were collected. Larvae were examined in the intermediate host snails by enzyme digestion method, while in paratenic host crabs by homogenization methods. The pulmonary arterial system was dissected to find the adult worms in definitive host rats. The intermediate hosts, paratenic hosts, and definitive hosts were found in the wild. The intermediate hosts and paratenic hosts were sold in the market. A total of 494 various hosts were examined, 49 were infected with the infection at a rate of 9.92%. Pomacea canaliculata, Achatina fulica and Limax sp. were collected in the field. The highest infection rate was 37.50% (21/56) in Limax, and the next was 21.43% (21/980) in Achatina fulica. Fifty-eight definitive hosts rodents were captured and the infection rate was 1.72% (1/58), the main infection species was Rattus flavipectus. Pomacea canaliculata, Cipangopaludina, Sinotaia quadrata and crabs were collected in the market. The highest infection rate was found in Sinotaia quadrata, at 17.39% (4/23), followed by Pomacea canaliculata at 4.35% (2/46). No infection was found in the crabs. In conclusion, Beihai City is the epidemic focus of Angiostrongylus cantonensis and natural infection was found in its intermediate and definitive hosts.
Characterization of free endogenous sphingoid bases in the golden apple snail Pomacea canaliculata: involvement in snail development and nutrient limitation by Qiong Yangab, Xiwang Lib, Xianwen Linb, Ying Zhoub, Jingqun Yuanc, Huadi Wangd, Jiaan Chengb, Cungui Maoe & Zengrong Zhub* , a Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, China, b State Key Laboratory of Rice Biology, Ministry of Agriculture and Institute of Insect Sciences, Zhejiang University, China, c Center for Chemical Analysis and Detection, Zhejiang University, China,d Bureau of Plant Protection and Quarantine, Department of Agriculture, Zhejiang, China,e Department of Medicine and Biochemistry, Medical University of South Carolina, Charleston, SC, 2825, USA, Invertebrate Reproduction & Development March 4, 2013
Abstract. A high-performance liquid chromatography-based method was developed for the analysis of free sphingoid bases endogenous to the golden apple snail (Pomacea canaliculata). Four molecular species of free endogenous sphingoid bases were observed in the snail and identified as C14 and C16 sphingosine (SPH), C14 dihydrosphingosine, and C16 sphingadienes with Δ-4,6 conjugated double bonds (Δ-4,6-C16 sphingadienes). When free endogenous sphingoid bases were evaluated at different stages of development of P. canaliculata, it was found that all four sphingoid bases decreased significantly from a young age to adulthood. We also found that the amount of C14 SPH decreased significantly in the food-restricted snails compared to animals with an adequate food supply, suggesting that nutrient deprivation decreases the levels of the sphingoid base. Taken together, these results suggest that sphingoid bases may play roles in the development of the golden apple snail and its stress response to nutrient limitation.
Climate and pH Predict the Potential Range of the Invasive Apple Snail (Pomacea insularum) in the Southeastern United States by J E Byers, W G McDowell, S R Dodd, R S Haynie, L M Pintor, et al., PLoS ONE 8(2): e56812, 2013
Abstract. Predicting the potential range of invasive species is essential for risk assessment, monitoring, and management, and it can also inform us about a species’ overall potential invasiveness. However, modeling the distribution of invasive species that have not reached their equilibrium distribution can be problematic for many predictive approaches. We apply the modeling approach of maximum entropy (MaxEnt) that is effective with incomplete, presence-only datasets to predict the distribution of the invasive island apple snail, Pomacea insularum. This freshwater snail is native to South America and has been spreading in the USA over the last decade from its initial introductions in Texas and Florida. It has now been documented throughout eight southeastern states. The snail’s extensive consumption of aquatic vegetation and ability to accumulate and transmit algal toxins through the food web heighten concerns about its spread. Our model shows that under current climate conditions the snail should remain mostly confined to the coastal plain of the southeastern USA where it is limited by minimum temperature in the coldest month and precipitation in the warmest quarter. Furthermore, low pH waters (pH <5.5) are detrimental to the snail’s survival and persistence. Of particular note are low-pH blackwater swamps, especially Okefenokee Swamp in southern Georgia (with a pH below 4 in many areas), which are predicted to preclude the snail’s establishment even though many of these areas are well matched climatically. Our results elucidate the factors that affect the regional distribution of P. insularum, while simultaneously presenting a spatial basis for the prediction of its future spread. Furthermore, the model for this species exemplifies that combining climatic and habitat variables is a powerful way to model distributions of invasive species.
Comparative analysis of circulating hemocytes of the freshwater snail Pomacea canaliculata, Alice Accorsia, Laura Buccib, Magda de Eguileorc, Enzo Ottaviania, and Davide Malagolia, , a Dept. of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy,b Dept. of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italyc Dept. of Biotechnology and Life Sciences, University of Insubria, Varese, Italy, Fish & Shellfish Immunology, February 16, 2013
Abstract. Mollusks are invertebrates of great relevance for economy, environment and public health. The numerous studies on molluscan immunity and physiology registered an impressive variability of circulating hemocytes, cells that play a role in the immune system of invertebrates. This study is focused on the first characterization of the circulating hemocytes of the freshwater gastropod Pomacea canaliculata, a model for several eco-toxicological and parasitological researches. Flow cytometry analysis identified two populations of hemocytes on the basis of differences in size and internal organization. The first one contains small and agranular cells. The second population displays major size and a more articulated internal organization. Light microscopy evidenced two principal morphologies, categorized as Group I (small) and II (large) hemocytes. Group I hemocytes present the characteristics of blast-like cells, with an agranular and acidophilic cytoplasm. Group I hemocytes can adhere onto a glass surface but seem unable to phagocytize heat-inactivated Escherichia coli. The majority of Group II hemocytes displays an agranular cytoplasm, while a minority presents numerous granules. Agranular cytoplasm may be acidophilic or basophilic. Granules are positive to neutral red staining and therefore acidic. Independently from their morphology, Group II hemocytes are able to adhere and to engulf heat-inactivated E. coli. Transmission electron microscopy analysis clearly distinguished between agranular and granular hemocytes and highlighted the electron dense content of the granules. After hemolymph collection, time-course analysis indicated that the Group II hemocytes are subjected to an evident dynamism with changes in the percentage of agranular and granular hemocytes. The ability of circulating hemocytes to quickly modify their morphology and stainability suggests that P. canaliculata is endowed with highly dynamic hemocyte populations able to cope with rapid environmental changes as well as fast growing pathogens.
Threshold Temperatures and Degree-Day Estimates for Embryonic Development of the Invasive Apple Snail Pomacea canaliculata by María E. Seuffert , Lucía Saveanu & Pablo R. Martín, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina, Malacologia 55(2):209-217, September 12, 2012
Abstract. Pomacea canaliculata is a freshwater snail native to subtropical-temperate South America that has invaded several countries around the world. Temperature is probably one of the main limitations to the expansion of this and other apple snails to higher latitudes in invaded regions. Egg masses are aerial, and the duration of embryonic development varies greatly with air temperature. We compared different methods for determining the lower temperature thresholds and the cumulative degree-days (DD) required for the completion of the embryonic development of P. canaliculata. The lower temperature threshold was estimated with four methods: the least standard deviation from the mean of degree-days, the least standard deviation from the mean of days, the coefficient of variation in days and the linear regression coefficient method. The cumulative degree-days were estimated using hourly records and daily averages (calculated according to the single triangle and the single sine methods) of air temperature. The lower temperature thresholds ranged between 15.8°C and 18.3°C and the cumulative DD between 88.8°C.d and 133.8°C.d. The estimations obtained with the single triangle and the single sine methods were exactly the same. The values obtained with the method of the least standard deviation in degree-days and the corresponding cumulative DD were the poorest estimations. The estimates obtained with daily mean temperatures were close to those obtained with hourly records, indicating that recording only maximum and minimum temperatures should be sufficient. The use of degree-day models for egg development in Pomacea will serve to increase the effectiveness and efficacy of control measures targeted to egg masses through a better timing in their application, especially in localities with highly variable temperatures.
Comparing apples with apples: clarifying the identities of two highly invasive Neotropical Ampullariidae (Caenogastropoda) by KENNETH A. HAYES1,*, ROBERT H. COWIE1, SILVANA C. THIENGO2, and ELLEN E. STRONG3, 1Center for Conservation Research and Training, Pacific Biosciences Research Center, University of Hawaii, 3050 Maile Way, Gilmore 408, Honolulu, HI 96822, USA,2Instituto Oswaldo Cruz/Fiocruz, Av. Brasil 4365, 2104-900 Rio de Janeiro, RJ, Brasil,3Smithsonian Institution, National Museum of Natural History, P.O. Box 37012, MRC 163, Washington, DC, WA 20013-7012, USA, Zoological Journal of the Linnean Society, Volume 166, Issue 4, pp 723–753, December 2012
Abstract. Ampullariidae comprises two lineages of freshwater gastropods: one Old World and one New World. Recent molecular work confirmed the monophyly of the family and began to clarify generic relationships, but current systematics remains unsatisfactory. With more than 300 available species group names for New World taxa alone, taxonomic confusion is rampant, as illustrated by two species that have been introduced widely and are difficult to differentiate conchologically, Pomacea maculata Perry, 1810 and Pomacea canaliculata (Lamarck, 1822). Misidentification hampers efforts to manage their spread and impacts as invasives, and prevents meaningful comparative analyses of their biology. Here we clarify the taxonomy, describe the morphological and genetic distinctiveness of the two species, and re-evaluate their biogeographic ranges. They differ most clearly genetically, with no shared haplotypes and a mean genetic distance of 0.135 at cytochrome c oxidase subunit I (COI). Differences in shell morphology are most obvious in recently hatched juveniles; the number of eggs per clutch is higher in P. maculata, and the individual eggs are smaller, so P. canaliculata hatchlings are nearly twice as large as those of P. maculata. Adult shells differ primarily in the angulation of the whorl shoulder and pigmentation of the inner pallial lip, with the latter a distinctive feature of P. maculata. They also differ in reproductive anatomy, most notably in P. canaliculata having two distinctive glandular tissues in the apical penial sheath gland, and P. maculata lacking a medial sheath gland but possessing a basal sheath gland. Pomacea canaliculata is restricted to a narrower southern range, whereas P. maculata ranges extensively throughout much of South America. Ampullaria gigas Spix, 1827 and Ampullaria insularum d’Orbigny, 1835 are herein synonymized with P. maculata. Neotypes are designated for P. maculata and A. gigas, and a lectotype is designated for A. insularum. A neotype is designated for P. canaliculata.
Characteristics of Feeding Preference and Nutrients Utilization of Golden Apple Snail (Pomacea canaliculata) on Macrophytes in Paddy Fields by Benliang Zhao, Wei Dai, Jia-en Zhang, Chaogang Cheng, Gen Li; Advance Journal of Food Science and Technology; 4 (5); 316-321; October 20, 2012.
Abstract. Golden apple snail was a harmful invasive gastropod in Asian wetlands. In order to clarify the effect of Pomacea canaliculata on macrophytes in paddy fields, feeding preference and nutrients utilization of snail were studied. Feeding preference of snail was Alternanthera philoxeroides >Monochoria vaginalis >Oryza sativa. Snail showed a higher approximate digestion coefficient on Oryza sativa than that on Monochoria vaginalis. Nitrogen utilization coefficient of snail on Alternanthera philoxeroides was significantly higher than that on Oryza sativa. Snail exhibited a higher calcium utilization coefficient on Alternanthera philoxeroides and Monochoria vaginalis than that on Oryza sativa. Oryza sativa L. was not preferred among three plants under the same available and exposure condition.
Bioaccumulation of heavy metals in water, sediments, aquatic plant and histopathological effects on the golden apple snail in Beung Boraphet reservoir, Thailand by Vipawee Dummeea, b, Maleeya Kruatrachuea, b, c,, Wachareeporn Trinachartvanita, b, Phanwimol Tanhand, Prayad Pokethitiyooka, b, and Praneet Damrongphola, b; a Department of Biology, Faculty of Science, Mahidol University, b Center for Environmental Health, Toxicology and Management of Chemicals, c Mahidol University International College, Mahidol University, d Department of Pharmacology, Faculty of Veterinary Medicine, Kasetsart University, Thailand; Ecotoxicology and Environmental Safety, Available online 15 October 2012
Abstract. Changes in the seasonal concentrations of heavy metals (Cu, Mn, Fe, Zn, Pb and Cd) were determined in water, sediments, snails (Pomacea canaliculata) and aquatic plants (Ipomoea aquatica) in three selected tributaries of the Beung Boraphet reservoir, Nakhon Sawan Province, central Thailand. Only Fe, Cu, Mn and Zn were detected by FAAS in all samples collected. The water quality of Beung Boraphet was medium clean with Fe, Mn, Cu and Zn concentrations well below internationally accepted limits. According to the criteria proposed for sediments by the EPA Region V, Zn and Mn concentrations were within the non-polluted range while Fe and Cu (wet season) concentrations fell into the class of severely polluted sediment. Both P. canaliculata and I. aquatica bioconcentrated more Mn in their tissues than were found in sediments, especially in the wet season. The results of Pearson correlation study and BCF values also indicated similar findings. Only Mn showed the importance of sediment-to-snail concentration and high BCF values in both snails and plants. P. canaliculata exposed to contaminated sediment for two months, showed higher accumulation of metals (Fe, Mn, Cu and Zn) in the digestive tracts and digestive glands than in the foot muscles. Histopathological changes included alterations in the epithelial lining of the digestive tracts, digestive glands and the gills. Loss of cilia and increase in mucous cells were observed in the digestive tracts and gills, while the digestive glands exhibited an increase of dark granules and basophilic cells, and dilation of digestive cells. The results indicated that both P. canaliculata and I. aquatica could be used as biomonitors of sedimentary metal contamination for the Beung Boraphet reservoir.
Effect of Food Availability on Morphometric and Somatic Indices of the Apple Snail Pomacea canaliculata byNicolás E. Tamburi & Pablo R. Martín, Universidad Nacional del Sur, Departamento de Biología, Bioquímica y Farmacia, San Juan 670, 8000 Bahía Blanca, Argentina, Malacologia 55(1):33-41, September 2012
Abstract. Pomacea canaliculata is a freshwater snail native to South America that together with some congeners has invaded natural wetlands and paddy fields in several continents, especially in Southern Asia. The high variability in shape, color and thickness of Pomacea shells and the sexual dimorphism in many traits blurs the species limits and hampers taxonomic identification. Ecological characterization of habitat productivity based on shells was previously proposed for P. canaliculata but was never methodically explored. Using full siblings of P. canaliculata, we studied the effects of different chronic levels of food availability (from 100% to 20% of daily ingestion rate) on shell shape, somatic indices and sexual dimorphism at maturity. The eight specific morphometric and somatic indices investigated showed different combinations of the effects of food availability and sex: changes related to food availability but independent of sex (relative aperture width), sexual dimorphism independent of food availability (shell globosity and relative aperture expansion), and changes related to food availability and sex, without a noticeable interaction (organic density); a significant interaction that increases the intersexual differences when food availability increases was detected in some indices (relative operculum weight, overall shell density and relative shell investment). The organic density can be used as a condition index to indicate the actual trophic availability in the field, although it should be estimated separately for males and females. The relative aperture width and the overall shell density can be used as paleo-environmental indicators of productivity, as they can be measured on empty shells. The effect of water alkalinity should be taken into account should the latter be used.
Relative warp and correlation analysis based on distances of the morphological shell shape patterns of Pomacea canaliculata Lamarck from Japan and the Philippines by Carlo Stephen O. Moneva1, Mark Anthony J. Torres1, Takashi Wada2, Ravindra Joshi3, Cesar G. Demayo1, 1 Department of Biological Sciences, MSU-Iligan Institute of Technology, Philippines; 2 Kyushu-Okinawa National Agricultural Research Center, Koshi, Kumamoto, Japan; 3 College of Agriculture, Forestry and Fisheries, Fiji National University, Koronivia Republic of Fiji, Advances in Environmental Sciences International Journal of the Bioflux Society, Vol. 4, Issue 1, 2012
Abstract. The Golden Apple Snail (GAS), Pomacea canaliculata Lamarck is considered one of the serious agricultural pests of rice in Asia. Itis being argued that rapid invasion of this species in many variable habitats suggests genetic variability and differentiation which could be expressed at the level of the phenotype. It is therefore the major objective of the study to explore possible phenotypic differentiation in the organism especially in the shape of the shell using geometric morphometric (GM) analysis. Specifically, this study aimed to determine conchological variation in populations of GAS in the Philippines and Japan. Three aspects of the shell shape were studied, which includes the ventral/aperture, dorsal and the top/whorl portion of the shell using correlation analysis based on distances (CORIANDIS). CORIANDIS was used in order to visualize congruence of multivariate traits among P. canaliculata populations. The results showed that P. canaliculata shell varies in shape and variability may signify distinctive genotypes or adaptation to varying environments exhibited by Japan and the Philippines.
Freshwater snail Pomacea bridgesii (Gastropoda: Ampullariidae), life history traits and aquaculture potential 1,2Ana R. A. Coelho1,2, Gonçalo J. P. Calado3,4, and Maria T. Dinis1, 1 Centro de Ciências do Mar, Universidade do Algarve, Faro, Portugal; 2 Instituto Português de Malacologia, Zoomarine, Albufeira, Portugal; 3 Faculdade de Ciências Biomédicas, Universidade Lusófona de Humanidades e Tecnologias; Lisboa, Portugal; 4 IMAR, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal. AACL Bioflux Vol. 5 No. 3 pp. 168-181, 2012
Abstract. Investigations on the reproductive biology, life cycle and feeding habits of Pomacea bridgesii have been undertaken to assess its potential as a cultured species for the ornamental trade. The species is dioecious and, under optimal culture conditions of temperature and food supply, it can breed all year round. The total developmental period at 23±1°C varied from 15 to 24 days after oviposition. Hatching can last for up to 20 hours in the same egg cluster. Hatching success was very high (mean 94.56±0.62%) and no significant differences were observed in hatching rates between different clutch sizes. Development is direct and juveniles hatch at shell length (SL)=2.4±0.25 mm. Maturity is reached 192±1.5 days after hatching and at SL=32.80±2.03 mm. Two feeding experiments were undertaken to assess the impact of food type on juvenile survival during the first 8 days post-hatching and subsequent growth until 90 days post-hatching. Compatibility between other fish and plants fresh-water aquarium species were performed. A combination of environmental tolerance, moderately amphibious behavior, fast growth, short development and hatching at an advanced stage, compatibility with other aquarium species (fishes or other invertebrates), and simple low cost diet, make P. bridgesii highly suitable for intensive culture for the ornamental trade.
Azadiractha Indica Leaves and Seeds Extracts as Biopesticides for Controlling Golden Apple Snail, Pomacea Canaliculata bySiti Noor Hajjar Md Latip1, Mohd Zaidi Lakim, Anis Syahirah Abu Bakar1 1Faculty of Plantation and Agrotechnology, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, UMT, 11th International Annual Symposium on Sustainability Science and Management, Terengganu, Malaysia,July 9-11, 2012. Corresponding author’s e-mail: firstname.lastname@example.org
Abstract. The golden apple snail, Pomacea canaliculata is an invasive alien pest that seriously affects rice cultivation in many Asian countries. These freshwater molluscs devour young rice seedlings, causing extensive damage to both transplanted and direct seed. Most Asian farmers resort to short-term solutions by using molluscicides that have negative impacts on non-target organisms, aquatic biodiversity, and the environment. Due to the toxic hazards of the synthetic insecticides, biological control through botanical pesticides is the best alternative for reducing the golden apple snail’s damage in paddy fields. A pesticide has been formulated as an extract from the plant Azadiractha indica, commonly known as “neem.” The purposes of this study was to examine the potential of combination Azadiractha indica seeds and leaves as biopesticides for controlling different size of golden apple snail, Pomacea canaliculata and determine the LC50 value for controlling golden apple snail. The mortality of snails was observed every 24, 48, 72 and 96 hours. The study showed that there were significant differences in mortality of golden apple snail on three different combination of neem extraction. The combination neem extract with high percentage of neem seeds at 75% seed and 25% leaves give high mortality rate to the golden apple snail. However, there were no significant differences in sizes on mortality of golden apple snail after applying three different combination rates of neem extractions. The lethal concentration 50% (LC50) for golden apple snails was 32.839g for seeds part with the 95% confidence limit range of 8.041 – 44.487. Further study about the application of neem at the real situation in the paddy field should be done to determine the effect of the neem extraction with different environment situation.
Distribution of the apple snail Pomacea canaliculata in Pampean streams (Argentina) at different spatial scales by María E. Seuffert and Pablo R. Martín, ,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, 8000 Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina, Limnologica – Ecology and Management of Inland Waters, July 2, 2012
Abstract. Studies dealing with the distribution of freshwater mollusks in the Pampean plains are very scarce and have all focused on the determinants of their presence among different waterbodies. The aims of this study were to investigate the distribution of the apple snail Pomacea canaliculata among and within Pampean streams. The main sampling scheme included heterogeneous sections within different sites belonging to all the streams of the Encadenadas del Oeste basin (Buenos Aires Province), in which apple snails’ presence and abundance as well as several environmental variables were recorded. P. canaliculata was present in long streams originating in the Piedmont area, with the exception of one that suffered extensive dredging works but it was absent in short streams originating in the plains. Lower altitudes and higher organic matter contents characterized the inhabited sites among the long streams. At a smaller scale, higher concentrations of Na+ and lower levels of organic suspended matter characterized the inhabited sections. Within the short streams P. canaliculata was only found at sites located downstream from a connection to an inhabited long stream and hence constituted sink populations; short streams presented alkaline waters with high conductivity, very slow currents and no trees. The microhabitat of P. canaliculata was investigated at two sites from two different streams in which environmental variables were registered at individual snails’ locations and at systematically distributed points. Apple snails were more frequently found in places located close to the shore, where current velocity was usually low, sediments fine and rich in organic matter, and macrophytes abundant. These variables were all correlated at this small scale thus making their individual interpretation difficult. All the streams in this basin appear to be habitable for P. canaliculata, but the populations would only persist autonomously in the medium and low reaches on the long streams. The distribution within long streams is probably governed by stochastic patterns of extinction-colonization as a consequence of the variability of the climatic and hydrological conditions in this region.
Control the egg hatchling process of Pomacea canaliculata by water spraying and submersion by
Zhigao Wanga, Jicai Tana, , , Lin Tana, Jun Liua, b, and Lang Zhonga,a College of Bio-Safety Science and Technology, Hunan Agricultural University, Changsha, China, b Hunan Environment Biological Polytechnic, Hengyang, China, Acta Ecologica Sinica, Vol 32(4), June 30, 2012.
Abstract. Pomacea canaliculata (Lamarck) is an invasive snail species that has become a serious pest of rice and other hydrophytes. Usually it is aquatic but likes to lay its eggs higher than the waterline. In order to seek a feasible and efficient way to control the egg hatchling of this pest, here we systematically studied the effects of water spraying and submersion on its egg hatchling rates and durations. Our results demonstrated that water spraying and submersion could dramatically decrease the hatchling rates to maximal 5.8% and increase the hatchling duration up to 26.4 days on P. canaliculata. Not only the beginning time of water treatment, but also the frequencies of the water spraying is critical to control the hatchling rate and duration of P. canaliculata. Water submersion that began in 12 h after the eggs laid and lasted at least 48 h will significantly decrease the snails’ hatchling rates and extend the hatchling time. In addition, compared to spraying, the water submersion could achieve more remarkable effects. The capsule of the snail’s egg is able to withstand the water treatment. Based on our water spraying and submersion results, it can be inferred that 0–6 h after egg being laid, egg capsule precipitates are beginning to form, and this process will complete after 12–24 h. This special breeding characteristic of P. canaliculata makes the physical control by water treatment become feasible.
Phylogenetic evidence for multiple and secondary introductions of invasive snails: Pomacea species in the People’s Republic of China by Lv, S., Zhang, Y., Liu, H.-X., Hu, L., Liu, Q., Wei, F.-R., Guo, Y.-H., Steinmann, P., Hu, W., Zhou, X.-N. and Utzinger, J. National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland, University of Basel, Basel, Switzerland, Diversity and Distributions, June 4, 2012
Abstract. This study was conducted to determine the genetic diversity of invasive snails (Pomacea spp.) that are implicated in crop damage, environmental degradation and human disease, and to determine their distribution pattern in the People’s Republic of China.
We collected Pomacea snails in a national survey using a grid sampling approach. Overall, 544 snails from 54 sites were used for the present investigation. The mitochondrial cox1 gene was amplified and sequenced from all the snails. We determined and classified the haplotypes using network analyses and mapped them within P.R. China. Haplotypes from this study, together with sequences available from GenBank, were used to reveal the global distribution of Pomacea canaliculata and P. insularum.
We obtained 521 cox1 sequences and identified 24 unique haplotypes. Six haplotypes were commonly found in P.R. China. Two species, P. canaliculata and P. insularum, and one cryptic group were observed. The distribution of the 24 haplotypes across P.R. China shows a mosaic pattern. Globally, only six of 112 haplotypes of P. canaliculata, P. insularum, P. dolioides, P. lineata and P. paludosa are shared between introduced and native snail populations. We found 16 haplotype clusters, five of which occur in mainland P.R. China. Three of the five clusters could be traced back to South America. The remaining two clusters were unique to P.R. China.
Phylogenetic analyses indicate that P. canaliculata, P. insularum and two cryptic groups, discovered by the present and previous studies, coexist in the mainland of P.R. China. The mosaic distribution and the high diversity found in the collection sites suggests multiple and secondary introductions. The findings indicate the importance of preventing further intentional introductions and call for appraisal of the risk posed by these snails in vulnerable areas. Discrimination of the ecological impacts of the different species or genotypes will help to develop setting-specific management strategies.
Angiostrongyliasis in the Americas by Arnaldo Maldonado Jr.1, Raquel Simões1,2 and Silvana Thiengo1, 1Oswaldo Cruz Foundation, 2Federal Rural University of Rio de Janeiro, Zoonosis, Chapter 17, pp. 303-320. April 4, 2012.
Excerpts. Angiostrongylus cantonensis, the agent that causes eosinophilic meningoencephalitis, was first described in Canton, China, by Chen (1935), and is now dispersed to various Pacific islands, Australia, Africa, and more recently, the Americas (Foronda et al., 2010). It is believed that the initial dissemination to islands in the Pacific resulted from the introduction of naturally infected rats in containers coming from Asia (Diaz, 2008). The growing flows of global trade and tourism, as well as the spread of habits and customs among countries, have enabled the dispersion of the definitive and intermediate hosts of A. cantonensis (Cross, 1987). Currently there are reports of human infection in the United States (New et al., 1995), Cuba (Aguiar et al., 1981), Jamaica (Slom & Johnson, 2003), Ecuador (Dorta-Contreras et al., 2010) and Brazil (Lima et al., 2009.) In particular the introduction of the Achatina fulica in Brazil (Thiengo et al., 2007) and Pomacea canaliculata (Lamarck, 1822)in China are examples of the importance of exotic snails in the spread of this helminthiasis (Lv et al., 2008).
In China where P. canaliculata and A.fulica are widespread in the south of the country, the number of cases of eosinophilic meningoencephalatis has been increasing, and the transmission is linked to both species (Lv et al., 2008, 2009). In the last years, various outbreaks have been reported and the transmission in most of the cases was directly related to the consumption of P. canaliculata, considered currently the main cause of the spread of angiostrongyliasis in China (Lv et al. 2011). The first cases of eosinophilic meningitis recorded to South America were to Brazil in 2007 and in 2008 and A. fulica was considered the vector for three out of the four reported cases. One of the cases reported to Pernambuco, Northeastern region, was attributed to the ingestion of undercooked P. lineata specimens (Caldeira et al., 2007; Lima et al., 2009; Thiengo et al., 2010). In fact, specimens of A. fulica have been found infected with A. cantonensis larvae from two of the main Brazilian regions, South and Southeast, in the last five years (Maldonado et al., 2010). Hence, the emergence of eosinophilic meningitis is a matter of concern in Brazil as it is currently experiencing the explosive phase of the invasion of A.fulica, recorded in 24 out the 26 states and the Federal District (Thiengo et al., 2007, Zanol et al., 2010).
Apple snails and their endosymbionts bioconcentrate heavy metals and uranium from contaminated drinking water by Israel A. Vega, María A. Arribére, Andrea V. Almonacid, Sergio Ribeiro Guevara and Alfredo Castro-Vazquez, Environmental Science and Pollution Research, February 27, 2012
The differential ability of apple snail tissues, endosymbionts, and eggs to bioaccumulate several metals (Sb, As, Ba, Br, Zn, Cr, Fe, Hg, Se, and U) was investigated. Metal concentrations were determined by neutron activation analysis in several tissues, endosymbionts, and eggs from mature apple snails cultured in either drinking water or reconstituted water (prepared with American Society for Testing and Materials type I water). The highest bioconcentration factors (BCFs) in the midgut gland were found for Ba, Zn, Se, As, U, Br, and Hg (in decreasing order), while the highest in the kidney were for Ba, Br, and Hg. The foot showed the highest BCFs for Ba, Hg, Br, and Se (in decreasing order). Calcified tissues (uterus, shell) and eggs showed low BCFs, except for Ba. Both C corpuscles and gland tissue showed statistically higher BCFs than K corpuscles for Ba, Fe, U, Br, and Sb. The concentration of most of the studied elements was significantly lower in tissues and endosymbionts obtained from snails cultured in reconstituted water instead of drinking water. Snails cultured in reconstituted water and then exposed or not to Hg, As, and U (at the maximum contaminant level allowed by the US Environmental Protection Agency) also resulted in high levels accumulated in midgut gland, endosymbionts and kidney. Our findings suggest that the midgut gland (and the symbionts contained therein), the kidney, and the foot of Pomacea canaliculata may be useful bioindicators of Hg, As and U pollution in freshwater bodies and that the unrestricted use of ampullariid snails as human and animal food must be considered with caution.
Abstract. The golden apple snail, Pomacea canaliculata has become a major agricultural and environmental pest across Asia. Here, using the mitochondrial cytochrome oxidase I as a diagnostic, we develop a multiplex PCR, that discriminates P. canaliculata from the most common non-invasive Pomacea species, thereby providing a fast and reliable diagnostic tool.
Toxicological effect of Agave sisalana Perrine extract on golden apple snail by Li LinFeng; Xu WuBing; Zhong QiuHua; Zhang JiaEn; Luo MingZhu; Zhao BenLiang; Qin Zhong, Zhongguo Shengtai Nongye Xuebao / Chinese Journal of Eco-Agriculture 2012 Vol. 20 No. 1 pp. 69-74 (2012)
Abstract. Pomacea canaliculata Lamarck is an invasive alien species that is very harmful to the ecosystem and rice production in South China. To verify the toxicity and related mechanism of Agave sisalana Perrine to golden apple snail, the toxic effects of aqueous, n-butanol and ethanol extracts of A. sisalana were tested via the snail-immersed method. The effects of n-butanol (59 mg.L-1, 96 mg.L-1) and ethanol (180 mg.L-1, 325 mg.L-1) extracts on cholinesterase (ChE), superoxide dismutase (SOD) and adenosine triphosphatase (ATPase) activities in hepatic tissue of golden apple snails were also investigated. Based on the results, aqueous, n-butanol and ethanol extracts of A. sisalana had toxic effects on golden apple snail. Their semi-lethal concentrations (LC50) on golden apple snail for 72 h toxicity exposure were 35.3 g.L-1, 93.3 mg.L-1 and 298.6 mg.L-1, respectively. The corresponding 95% confidence interval ranges were 32.9-37.7 g.L-1, 87.6-99.7 mg.L-1 and 272.9-318.7 mg.L-1, respectively. When treated with n-butanol and ethanol extracts for 12 h, SOD activity in snail hepatic tissues showed no obvious change at low concentrations. SOD activity, however, increased significantly at high concentrations. After treatment for 48 h, SOD activity at high concentrations of n-butanol extract was significantly higher than that of the control. However, SOD activity did not show any obvious change in both low and high concentrations of ethanol extract. All A. sisalana extracts somehow increased ChE activity, with n-butanol extract exhibiting higher effect on ChE activity. When treated with 96 mg.L-1 n-butanol extract for 48 h, ChE activity significantly exceeded that of the control (P<0.05). Overall, n-butanol extract treatment enhanced ATPase activity at low concentrations and suppressed it at high concentrations. Irrespectively, no obvious pattern change was noted under ethanol extract treatment. In conclusion, A. sisalana was somehow toxic to golden apple snails. A better mode of application was needed for future exploitations.
A lentic dweller in lotic habitats: the behavior of the invasive South American apple snail Pomacea canaliculata in flowing water by María E. Seuffert and Pablo R. Martín, Aquatic Ecology, Online First™, 12 December 2011
Abstract. The aim of this study was to test the hypothesis that positive rheotaxis and anti-detachment behaviors contribute to the persistence of Pomacea canaliculata in lotic environments. This invasive apple snail is commonly considered a lentic dweller. In a first series of trials in a laboratory flume, current velocity was gradually increased until snails’ detachment. Detachment velocity was highly variable, with some snails able to withstand strong currents during short periods. Sexually undifferentiated snails were the most resistant to detachment; most of the snails that resisted high velocities were facing flow before detachment. In a second series of trials, snails’ net displacement was estimated at three fixed velocities (0, 0.15, and 0.30 m s−1). Current velocity did not influence mean net displacement, which was not different from zero. Marked snails were released in a stream and recaptured 24 h later estimating their net displacement. Most recovered snails dispersed a short distance from the release point and crawled through sites with very low current velocities. A small proportion of snails drifted downstream, indicating the existence of different dispersal mechanisms. Snails were able to resist current velocities that are among the highest recorded in streams in the Pampas region. P. canaliculata did not show a positive rheotactic response; in flowing water, snails crawl more often upstream, but at a slower pace than downstream. At the population level, a slow upstream spread seems possible in plain’s streams, probably being enough to compensate drift, but not to colonize headwaters. Irrigation systems are feasible pathways for the spread of this species in invaded regions.
Population genetics of Pomacea spp. in mainland of China by Lv Shan; Zhang Yi; Liu HeXiang; Hu Ling; Liu Wei; Liu Qin; Li ShiZhu; Hu Wei; Utzinger, J.; Zhou XiaoNong, Chinese Journal of Schistosomiasis Control 2011 Vol. 23 No. 2 pp. 178-182 (2011)
Abstract: To reveal the population structure of Pomacea spp. using genetic markers so as to provide the evidence for studying the invasion and expansion of it in the mainland of China. Methods: The genetics of 581 specimens of Pomacea spp. from 60 sites was analyzed by sequencing CO I gene. The diversity of nucleotide and haplotypes were calculated in DnaSP 5.10.01. The haplotype network analysis was performed in Network 22.214.171.124. A phylogenetic tree was produced based on the haplotypes from the present study and those available from GenBank in order to understand the taxonomic status of Pomacea spp. in China. Results: A total of 556 sequences were acquired in the present study and produced 25 unique haplotypes. Six haplotypes frequently occurred in the specimens and accounted for 96.0%. The phylogenetic analysis identified two Pomacea species in China, i. e. P. canaliculata and P. insularum. The usage of haplotypes of P. insularum in China reversed from the existing pattern in other countries. Conclusion: The complexity of population structure of Pomacea spp. in the mainland of China indicates multi-original introduction and complicated expansion patterns.
Abstract: The present experiment was conducted to study the effect of temperature on growth, development, reproduction and feeding behavior of Pomacea canaliculata in order to find out a suitable temperature for its population reproduction, and specially to investigate its growth and development mechanism to deal with disastrous conditions caused by it. The survival and growth rate, egg production and food intake of P. canaliculata were investigated by raising them under various temperature conditions at different developmental stages. The young and adult P. canaliculata attained highest survival rate (over 90%) at 15-20°C, the body weight increment rate of young P. canaliculata, egg production quantity and rate of egg hatching reached the highest at 30°C. The average maximum food intake level of young and adult P. canaliculata was found highest at 30 and 35°, respectively. The threshold temperature for development of eggs was 14.19°C, and the effective accumulated temperature was 137.41°C.d. Conclusion: The results revealed that 30°C was the best temperature for the growth, development and reproduction of P. canaliculata.
AN OUTBREAK OF ANGIOSTRONGYLIASIS IN GUANGING, PEOPLE’S REPUBLIC OF CHINA: MIGRANTS VULNERABLE TO AN EMERGING DISEASE by DENG Zhuo-Hui (1) ; SHAN LV (2) ; LIN Jin-Yan (1) ; LIN Rong-Xing (1) ; PEI Fu-Quan (1) ;(1) The Institute of Parasitic Diseases, Center for Disease Control and Prevention of Guangdong Province, Guangzhou, CHINE, (2) National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, CHINE, Southeast Asian journal of tropical medicine and public health, 2011, vol. 42, no5, pp. 1047-1053
Abstract. Angiostrongyliasis has been frequently reported from the People’s Republic of China during the last decade. An outbreak of angiostrongyliasis among migrant laborers in Guangning, Guangdong Province is described here. A questionnaire was developed to collect epidemiological and clinical information about 17 migrant laborers from the Bai ethnic group in Dali, Yunnan Province. Serum samples were collected and tested by enzyme-linked immunosorbent assay. Rats and mollusks from the same area where patients had collected Pomacea canaliculata were examined for presence of Angiostrongylus cantonensis. All 17 Bai migrant laborers consumed P. canaliculata and six had meningitis 3-19 days after consumption of P. canaliculata. Headache, myalgia and fatigue were the most common symptoms. Blood samples from 5 patients were positive for antibodies to A. cantonensis. The places where the migrant laborers collected P. canaliculata were identified as endemic areas for A. cantonensis. This outbreak highlights the vulnerability of migrants to angiostrongyliasis.
Loop-mediated isothermal amplification: rapid detection of Angiostrongylus cantonensis infection in Pomacea canaliculata by Rui ChenQunBo TongYi ZhangDi LouQingMing KongShan LvMingMing ZhuoLiYong WenShaoHong, Parasites &Vectors, 4:204, October 25, 2011
Abstract. Angiostrongylus cantonensis is a zoonotic parasite that causes eosinophilic meningitis in humans. The most common source of infection with A. cantonensis is the consumption of raw or undercooked mollusks (e.g ., snails and slugs) harbouring infectious third-stage larvae (L3). However, the parasite is difficult to identify in snails. The purpose of this study was to develop a quick, simple molecular method to survey for A. cantonensis in intermediate host snails.
Findings: We used a loop-mediated isothermal amplification (LAMP) assay, which was performed using Bst DNA polymerase. Reactions amplified the A. cantonensis 18S rRNA gene and demonstrated high sensitivity; as little as 1 fg of DNA was detected in the samples. Furthermore, no cross-reactivity was found with other parasites such as Toxoplasma gondii, Plasmodium falciparum, Schistosoma japonicum, Clonorchis sinensis, Paragonimus westermani and Anisakis. Pomacea canaliculata snails were exposed to A. cantonensis first-stage larvae (L1) in the laboratory, and L3 were observed in the snails thirty-five days after infection. All nine samples were positive as determined by the LAMP assay for A. cantonensis, which was identified as positive using by using PCR and microscopy, this demonstrates that LAMP is sensitive and effective for diagnosis.
Conclusions: LAMP is an appropriate diagnostic method for the routine identification of A. cantonensis within its intermediate host snail P. canaliculata because of its simplicity, sensitivity, and specificity. It holds great promise as a useful monitoring tool for A. cantonensis in endemic regions.
First provincial survey of Angiostrongylus cantonensis in Guangdong Province, China by Zhuo-Hui Deng1, Qi-Ming Zhang1, Shao-Yu Huang1, Jeffrey L. Jones2, 1. Institute of Parasitic Diseases, Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China,2. Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA,Tropical Medicine & International Health, published online: September 9, 2011
Abstract. The rat lungworm Angiostrongylus cantonensis is a zoonotic nematode with a wide distribution. We report the first provincial survey of the prevalence of A. cantonensis infection among wild rodents and snails in Guangdong Province, China. A total of 2929 Pomacea canaliculata and 1354 Achatina fulica were collected from fields in 22 survey sites with a larval infection rates ranging from 0–26.6% to 0–45.4%. In addition, 114 Cipangopaludina sp and 252 Bellamya sp were bought from markets; larvae were found only in Bellamya snails from two survey sites with an infection rate of 1.4% (1/70) and 3.3% (3/91), respectively. Four hundred and ninety-one rodents were captured in nine sites (Rattus norvegicus, R. flavipectus, Suncus murinus, Mus musculus, Bandicota indica, R. losea and R. rattus). Adult worms were found in R. norvegicus, R. flavipectus and Bandicota indica. Our survey
revealed a wide distribution of A. cantonensis and its intermediate hosts P. canaliculata and A. fulica in Guangdong. The prevalence of A. cantonensis in wild snails and rats poses a substantial risk for angiostrongyliasis in humans.
High tolerance to abiotic stressors and invasion success of the slow growing freshwater snail, Melanoides tuberculatus byScott M. Weir and Christopher J. Salice, Biological Invasions Volume 14, Number 2, August 9, 2011
Abstract.Considerable research has been conducted to determine traits common to invasive species with the goal of predicting, preventing, or managing invasions. The importance of physiological tolerance to abiotic stressors in the ability of invasive species to establish and displace native species has been hypothesized to be important although there are few actual tests of the hypothesis in the literature. In freshwater molluscs it has been suggested that high fecundity is the most important trait for invasion success and that physiological tolerance to abiotic conditions is unlikely to play a significant role. We examined the tolerance to abiotic stressors using a known invasive snail species (Melanoides tuberculatus) that has a much slower growth rate and fecundity than a native species it has displaced (Biomphalaria glabrata). We tested the hypothesis that M. tuberculatus would have significantly greater tolerance to natural and anthropogenic abiotic stressors (cadmium, malathion, temperature extremes, and desiccation) which may provide a mechanism for displacement of B. glabrata. A time-to-event analysis was used to determine relative tolerance between species. M. tuberculatus was significantly more tolerant to the tested abiotic stressors than B. glabrata with the exception of low temperature (5°C). Stress tolerance may partly explain the ability of M. tuberculatus to displace B. glabrata despite having a much lower growth rate and fecundity. These results also suggest that M. tuberculatus is likely to have a strong advantage in disturbed or polluted habitats. Identifying those traits most important for the invasion success of particular species could be used to better inform removal strategies and may allow for improved predictions of invasion potential.
Neem crude extract as Biomolluscicide for sustainable control of golden apple snail, Pomacea canaliculata by Massaguni, Rosdiyani; Latip, Siti Noor Hajjar Md; Faculty of Plantation and Agrotechnology, Universiti Teknologi MARA 40450 Shah Alam, Selangor, Malaysia, Sustainable Energy & Environment (ISESEE), 2011 3rd Internat’l Symposium & Exhibition in Malaca, Malaysia, June 1-3, 2011
Abstract. Golden apple snail, (Pomacea canaliculata) was reported could cause severe damage on food crop especially paddy, which is a staple food for more than 60% of the world population. The farmers mostly rely on chemical and synthetic molluscicides to overcome this problem which improper use of pesticide could give negative impact on environmental. Therefore, there is a need to determine the potential botanical molluscicides in order to ensure the low cost and efficient pest management control method along with protection of the environment. The present study investigated the toxicity of two different neem plant parts (leaves and seeds) against small (10–20mm) and large (20–40mm) sizes of golden apple snails using bioassay. The crude extract treatments were incorporated into the paddy seedlings as a food source of golden apple snails and the concentrations of the leaves and seeds crude extract, which killed 50% of the test population (LC50) determined the efficacy of selected extracts. From the result, both plant parts have ability in controlling golden apple snail but aqueous neem leaves crude extract was expressed the most effective controlled compared with aqueous seeds crude extract for both size of golden apple snails. It caused high rate of snail mortality after 96 hours with 93.33% and 84.17% compared to 71.67% and 73.33% for different sizes of golden apple snail, respectively. In addition, aqueous neem leaves crude extract also have the potency in controlling both sizes of golden apple snails with low concentration compared to aqueous neem seeds crude extract. In the observation of the toxicity effects, LC50 values was lower for neem leaves crude extract with of 44,196.9 ppm and 49,801.5 ppm followed by aqueous neem seeds crude extract with LC50 of 103,551 ppm and 104,475 ppm for both sizes of golden apple snails. The results of this study suggested that aqueous neem plant extract can be used for controlling golden – - apple snail and its application can be provided an alternative way for sustainable pest control in paddy field.
Effects of food availability on reproductive output, offspring quality and reproductive efficiency in the apple snail Pomacea canaliculata, Nicolás E. Tamburi and Pablo R. Martín, Biological Invasions, Online First™, 2 August 2011
Abstract. Phenotypic plasticity in life history traits favors the establishment of invaders and may magnify their ecological impacts. Pomacea canaliculata, the only freshwater snail listed among the 100 worst invaders worldwide, is able to complete its life cycle within a wide range of conditions, a capacity attributed to its life history plasticity. Using snails from their native range in Argentina we investigated the changes in fecundity, egg mass traits, offspring quality, and efficiency of food conversion into eggs in response todifferent levels of food availability throughout different life stages. Pre-maturity mortality was not affected by chronic reductions of up to 80% in food availability. Females fed ad libitum demonstrated no significant reproductive output differences when mated with males raised at different food availability levels. For females, the number and total weight of eggs and the size of egg masses decreased at high levels of food deprivation. Their efficiency of conversion into eggs of the food ingested during the reproductive period increased with deprivation, as did the survival time of their offspring. In contrast, the egg mass laying rate and th individual egg weight did not differ under different food availability regimes. Reductions in food availability have been suggested as a control method but our results indicate that fecundity would be lessened only at deprivation levels higher than 50% and would be partially compensated by an increase in hatchling survival.
QUITE THE APPETITE: JUVENILE ISLAND APPLE SNAILS (POMACEA INSULARUM) SURVIVE CONSUMING ONLY EXOTIC INVASIVE PLANTS by Romi L. Burks, Sarah A. Hensley, and Colin H. Kyle, J. Mollus. Stud. (2011), first published online July 29, 2011
Abstract. Most aquatic snails derive their energy by grazing periphyton. However, certain species, including the invasive island apple snail, Pomacea insularum, readily consume aquatic macrophytes. These snails often overlap in their distribution with other exotic, invasive plants. We sought to discover if juvenile P. insularum could survive and grow when fed only three reportedly less palatable food sources: Eurasian watermilfoil (Myriophyllum spicatum), wild taro (Colocasia esculenta) and water hyacinth (Eichhornia crassipes). Snails received non-rooted macrophytes simultaneously in a multiple-resource experiment. Using enclosures with compartments that
separated plants but allowed snails full access, we housed individual early (10.7 ± 0.9 mm operculum width; 0.56–1.11 g blotted wet weight; mean ± 1 SD) or late (23 ± 2 mm; 4.60–14.82 g) juvenile P. insularum. We monitored snail survival and growth for 6 weeks. As controls, we placed standardized non-rooted macrophytes in enclosures without snails for 1 week. Replacing plants weekly, we calculated average daily consumption rates. Both size classes of snails grew substantially in terms of
operculum width, shell height and blotted wet weight, with early juveniles exhibiting relatively larger gains in size over the 6-week period. No mortality occurred. Both size classes consumed significantly more watermilfoil than taro and more taro than water hyacinth. Collectively, these results translate into the potential for one single 10-g P. insularum (i.e. representative of the larger snails used in our experiment) to consume a combined 0.35 g of dried plant matter (or c. 3.5 g) of live macrophytes per day. Our study suggests that available resources offered by a community of exotic invasive plants may sustain snail survival.
Prime waterfront real estate: Apple snails choose wild taro for oviposition sites by Colin H. KYLE, Alexis W. KROPF, Romi L. BURKS, Current Zoology 57 (5): 630–641, 2011
Abstract. While difficult to prevent introductions, scientific research can help guide control efforts of exotic, invasive species. South American island apple snails Pomacea insularum have quickly spread across the United States Gulf Coast and few control measures exist to delay their spread. Usually occupying cryptic benthic habitats, female apple snails crawl out of the water to deposit large, bright pink egg clutches on emergent objects. To help identify the most likely place to find and remove clutches, we conducted four lab experiments to investigate what specific object qualities (i.e. material; shape and height; plant species; natural and artificial attracted P. insularum females to lay clutches. In our fourth experiment, we specifically examined the relationship between female size and reproductive output. To further understand reproductive output, we quantified experimental clutch characteristics (height above water, dimensions, mass, approximate volume, number of eggs, hatching efficiency). Pomacea insularum females laid more clutches on plant material, chose round over flat surfaces and failed to differentiate between tall and short structures. In comparison to a common native plant in the eastern US, Pontederia cordata, snails clearly preferred to lay clutches on a widely distributed exotic, invasive plant (wild taro, Colocasia esculenta). Unexpectedly, smaller snails showed higher overall total fecundity as well as more eggs per clutch than larger snails. Therefore, hand removal efforts of large females may not be enough to slow down clutch production. Collectively, our results indicate that conservationists and managers should search emergent plants for P. insularum clutches carefully to guard against established populations.
Are lower latitude plants betterdefended?: Palatability of freshwater macrophytes by Wendy Morrison1 and Mark Hay2,¤ 1Georgia Institute of Technology, Atlanta, GA, United States of America 2Georgia Institute of Technology, Atlanta, GA, Ecology, In Press, 2011.
Abstract. Increased herbivory at lower latitudes is hypothesized to select for more effective plant defenses. Feeding assays with seaweeds and salt marsh plants support this hypothesis, with low latitude plants experiencing greater damage in the field and being less palatable than higher latitude plants. We tested this hypothesis for freshwater macrophytes because they offered an independent plant lineage and habitat type for testing this general hypothesis and because the patchiness of consumer occupancy across isolated water bodies might produce local variance in herbivory that would override geographic variance and produce different results for this habitat type. When we fed 8 congeneric pairs of live plants from 4 sites in Indiana vs 4 sites in South Florida (~215 and 0 frost days/yr respectively) to three species of crayfishes and one species of snail, three of the four herbivores significantly preferred high-latitude to low-latitude plants. For two crayfishes that differed in feeding on live plants (one favoring high-latitude plants one not), we retested feeding using foods composed of freeze-dried and finely ground plants, thus removing structural characteristics while retaining most chemical/nutritional traits. In this assay, both herbivores strongly preferred high-latitude plants, suggesting that lower latitude plants had been selected for more deterrent chemical traits. When we collected 22 pairs of congeneric plants from 13 sites in Central Florida vs 9 sites throughout Indiana (~95 and ~215 frost days/yr respectively) and tested these in feeding assays with three crayfishes using dried, ground, and reconstituted plant material, we found a significant effect of latitude for only one of three species of herbivore. Overall, our results suggest a preference for high-latitude plants, but the strength of this relationship varied considerably across small scales of latitude that differed considerably in numbers of frost-free days. The difference in results suggests that large changes in frost frequency over small spatial scales may affect selection for plant defenses, that local variance in herbivory overrode differential selection at geographic scales, or that these possibilities interact when durations of cold weather periodically exclude herbivores from shallower habitats, producing heterogeneous selection for defenses at small spatial scales.
Effects of desiccation on two life stages of an invasive snail and its native cohabitant by Allison M. Wood, Cody R. Haro, Roger J. Haro and Gregory J. Sandland, Hydrobiologia, Published online on July 13,2011
Abstract. Invasive species are of critical concern as they have the potential to
rapidly alter biotic systems around the globe. The upper Mississippi River
(UMR) system has been recently invaded by the aquatic snail, Bithynia
tentaculata, which spread from the Great Lakes region. In addition to
potentially impacting native aquatic snails, B. tentaculata also carries
three parasites which kill thousands of migrating waterfowl annually. Although
this invader is having detrimental impacts on a number of species in the UMR
region, little is known regarding (1) the tolerances of B. tentaculata
to abiotic stresses in this area, and (2) how stress thresholds in this species
compare to native species across developmental stages. To help fill in these
informational gaps, we conducted a series of laboratory experiments aimed at
assessing the tolerances of B. tentaculata and a native snail (Physa
gyrina) to desiccation at two stages of ontogeny (eggs and adults). Results
showed that P. gyrina egg masses were more tolerant to a transient
desiccation period (9 h) than B. tentaculata egg masses as evidenced by
their higher hatching success. Conversely, adult survival in B. tentaculata
was much greater than that of P. gyrina after a longer desiccation
period (1 week). Although superior tolerance to drying varies between the
developmental stages of each species, B. tentaculata may have an overall
advantage due to its ability to endure prolonged drying at maturity. These
results suggest that hydrologic fluctuations in the UMR may contribute to
reductions in P. gyrina numbers, potentially facilitating B.
tentaculata colonization and the spread of waterfowl infections.
Human Angiostrongylus cantonensis: an update by Z.-D. Wu, J. Wei, R. L. Owen and Z.-R. Lun European Journal of Clinical Microbiology & Infectious Diseases, Volume 30, Number 9, 2011
Abstract. Angiostrongylus cantonensis was first discovered in 1935 and has become an important emerging pathogen causing human angiostrongyliasis. Major outbreaks of human angiostrongyliasis have been reported in endemic regions. Thousands of cases of human angiostrongyliasis have been documented worldwide. A. cantonensis has spread from its traditional endemic regions of the Pacific islands and Southeast Asia to the American continent including the USA, Caribbean islands and Brazil. Humans acquire A. cantonensis by consumption of raw or undercooked intermediate snail hosts or paratenic hosts. The main clinical manifestations of human angiostrongyliasis are eosinophilic meningitis and ocular angiostrongyliasis. The treatment of this disease includes supportive treatment, corticosteroid therapy, and combined therapy with corticosteroids and anthelminthics.
The most effective method for prevention is to persuade people not to eat raw or undercooked intermediate and paratenic hosts. The main dietary sources for human infection vary by geographic location and dietary custom. In China, Pomacea canaliculata and Achatina fulica are main vectors for human infection. P. canalicuta, native to South America, was introduced to Taiwan and the mainland of China in the 1980s. P.canalicuta has replaced the African giant snail, Achatinafulica, as a major intermediate host and has become the main source of human infection both in Taiwan and mainland China.
Living on the edge: Potential fates of apple snail (Pomacea insularum) eggs laid on emergent variation in riparian areas by Romi L. Burks, Allyson K. Plantz, Megan E. Rice,Tracy Day , Biology, Southwestern University, Georgetown, TX, 96th Annual Earth Stewardship Association Meeting, Austin Texas, August 11, 2011.
To invade on a larger landscape scale, exotic species must
establish reproducing populations within their introduced habitat. In many
cases, exotic species successfully exploit unique, well delineated habitats
with a particular range of environmental conditions that do not vary
substantially. Such habitat stability allows for an increased likelihood of
reproductive success. The island apple snail, Pomacea insularum,
however, must confront a number of obstacles to survive in both aquatic and
terrestrial habitats. Usually occupying cryptic benthic habitats, female apple
snails crawl out of the water to deposit large, bright pink egg clutches on
emergent objects. These clutches must then dry in the terrestrial, or riparian,
environment before yielding hatchlings that drop back down into the water.
Collectively, our work examines the implications of “living on the edge” where
eggs clutches, and subsequently hatchlings, may face multiple stresses
including predation by riparian predators, inundation, nutrient pollution and
consumption by aquatic predators including adult apple snails. We tested the
predatory potential of red-eared slider turtles (Trachemys scripta elegans)
to consume eggs and hatchlings. We also examined the hatching efficiency,
growth and survival of 9-day old clutches subjected to eight hours of
inundation stress (none, low and high intensity) followed by excess nutrients
(N, P & N+P). Our investigations also included examining the likelihood of
egg or hatchling consumption by adult snails.
Clutches laid by P. insularum routinely hatch with an
efficiency ranging between 60 and 80%. This translates into an average of
1200-1600 hatchlings emerging from each clutch laid by an invasive female. Both
small (i.e. baby) and large (i.e. adult) red-eared sliders consumed nearly 100%
of apple snail eggs when offered in the water. However, baby sliders failed to
show interest in clutches above the surface. In contrast, adult sliders
partially consumed (~50%) clutches dangled from a string. Alarmingly,
inundation stress did not significantly reduce hatching efficiency of 9-day old
clutches. However, exposure to high levels of nutrients decreased growth and
resulted in lower survival of 1-week old hatchlings compared to controls. Such
susceptibility of hatchlings to nutrient levels suggests a noticeable immediate
mortality. We found that adult snails consumed about 10% of available
hatchlings. Connected together, our results point to the particular challenge
of living on the edge where dual habitats of riparian vegetation and aquatic
environments may ultimately work together to limit reproductive success of P.
insularum. We recommend more work to quantify hatchling survivorship and
Assessment of the camellia seed meal impact on loaches in paddy fields by Rong-Song Chen, Kuo-Liang Wang, and Chia-Ying Wu, Department of Civil Engineering, National Chung-Hsing University, Taichung City, Taiwan, Paddy and Water Environment, Volume 9, Biomedical and Life Sciences, June 29, 2011
Abstract. Results indicated that the best application to stop the growth of Pomacea canaliculata is to seal the rice field immediately after transplantation, apply the camellia seed meal, and then irrigate the field 2 days after camellia seed meal application for the summer transplantation, and 3 days for the spring transplantation. Water should not be drained from the paddy field after the application of camellia seed meal to reduce the chance of endangering fish in irrigation canals. Field Tests show that high water temperature during summer also has a negative effect on fish in paddy fields and irrigation canals.
Molluscicidal activity of cardiac glycosides from Nerium indicum against Pomacea canaliculata and its implications for the mechanisms of toxicity by Lingpeng Daia,, Wanxian Wangb, Xinjiao Donga, Renyong Hua
and Xuyang Nana a School of Life and Environmental Science, Wenzhou University,
Wenzhou 325027, PR Chinab School of Life Science, Hubei University, College Road 11, Wuhan 430062, PR China, EnvironmentalToxicology and Pharmacology,
1 June 2011.
Abstract. Cardiac glycosides from fresh leaves of Nerium indicum were evaluated for its molluscicidal activity against Pomacea canaliculata (golden apple snail: GAS) under laboratory conditions. The results showed that LC50 value of cardiac glycosides against GAS was time dependent and the LC50 value at 96 h was as low as 3.71 mg/L, which was comparable with that of metaldehyde at 72 h (3.88 mg/L). These results indicate that cardiac glycosides could be an effective molluscicide against GAS. The toxicological mechanism of cardiac glucosides on GAS was also evaluated through changes of selected biochemical parameters, including cholinesterase (ChE) and esterase (EST) activities, glycogen and protein contents in hepatopancreas tissues of
GAS. Exposure to sublethal concentrations of cardiac glycosides, GAS showed lower activities of EST isozyme in the later stages of the exposure period as well as drastically decreased glycogen content, although total protein content was not affected at the end of 24 and 48 h followed by a significant depletion at the end of 72 and 96 h. The initial increase followed by a decline of ChE activity was also observed during the experiment. These results suggest that cardiac glycosides seriously impair normal physiological metabolism,resulting in fatal alterations in major biochemical constituents of hepatopancreas tissues of P. canaliculata.
Haemolymph plasma constituents of the invasive snail Pomacea canaliculata by JUAN A. CUETO 1, MAXIMILIANO GIRAUD-BILLOUD 1, ISRAEL A. VEGA 1 & ALFREDO CASTRO-VAZQUEZ 1,2,* 1Laboratory of Physiology (IHEM-CONICET), Department of Morphology and Physiology, National University of Cuyo, Mendoza, Argentina, and,2Centro Nacional Patagónico (CENPATCONICET), Puerto Madryn, Argentina, April, 21, 2011.
Abstract. Haemolymph plasma constituents were studied in Pomacea canaliculata. Osmolality, pH, electrolytes, two metals, monosaccharides, total proteins, free amino acids and other nitrogen compounds were measured. Glucose, but not galactose, was detected in plasma. Cations found (in decreasing order)were sodium, calcium, potassium and magnesium. Chloride was the main inorganic anion, followed by bicarbonate and phosphate. Total plasma copper (the metal constituent of haemocyanin) was in a much higher concentration than that of total iron. Ammonia was the main nitrogen-excretory compound. Uric acid showed a lower concentration in plasma, while urea was undetectable (<0.08 mmol/L). Seventeen proteinogenic amino acids were investigated: two-digit mM concentrations were found for glutamine, alanine, valine, methionine, threonine and leucine, while one-digit mM concentrations were found for proline, phenylalanine, isoleucine, serine, glycine and glutamic acid; histidine, tyrosine, tryptophan, lysine and aspartic acid were undetectable (<0.2 mmol/L). This is the most comprehensivereport on haemolymph plasma constituents in a gastropod species, and results are discussed in the context of what is known for other gastropods.
Histopathological Effects of Contaminated Sediments on Golden Apple Snail (Pomacea canaliculata, Lamarck 1822) by M. Kruatrachue, C. Sumritdee, P. Pokethitiyook and S. Singhakaew, Bulletin of Environmental Contamination Toxocology, Volume 86, OnLineFirsttm, April 23, 2011
Abstract. Pomacea canaliculata were exposed experimentally to contaminated sediments from a tributary of the Mae Klong River, Thailand, for 3 months. The highest concentration of Cr, Zn and Fe accumulated in the digestive gland while the gill exhibited the highest concentration of Cu. In addition, histopathological changes (increased mucus vacuoles, loss of cilia, dilation of cells in the epithelial cells of digestive tract organs, and an increase in the number of dark granules in the digestive cells) were observed. The gill exhibited loss of cilia, wider hemolymph space, and degeneration of columnar epithelial cells.
Bioaccumulation of microcystins by fish associated with a persistent cyanobacterial bloom in Lago de Patzcuaro (Michoacan, Mexico) by John P. Berry1,*, Elisha Lee1, Katherine Walton1, Alan Wilson2, Fernando Bernal-Brooks, Environmental Toxicology and Chemistry, Volume 30, Issue 5, May 2011
Abstract. Lago de Patzcuaro is a historically important freshwater fishery in Mexico. The lake is currently characterized by a persistent bloom of cyanobacteria, specifically dominated by recognized producers of toxic microcystins (MCYSTs). We evaluated MCYSTs in sestonic and dissolved fractions of the water column, as well representative fish species (silversides, Chirostoma spp.; Goodea sp.; and carp, Cyprinus carpio) obtained from local markets and small commercial catches during the bloom. Samples were evaluated primarily by enzyme-linked immunosorbent assay (ELISA), and secondarily by protein phosphatase (PPase) inhibition assay and liquid chromatography-mass spectrometry (LC-MS). Sestonic MCYST concentration (0.02-0.36 µg/L) generally correlated inversely with distance from the bloom, supporting the bloom as the source of the toxin. Several MCYST variants, including MC-LR, -LA and –LY, as well as didemethyl variants, were identified by LC-MS/MS analysis. All three species of fish bioaccumulated MCYSTs in relevant tissues, and toxin content correlated with trophic level, with highest and lowest levels measured in phytoplanktivorous and zooplanktivorous representatives, respectively. Detection of MCYST in silversides and Goodea sp. is particularly relevant because both are consumed in their entirety, including viscera (e.g., liver) known to primarily accumulate MCYST. These results indicate that Lago de Patzcuaro is, indeed, characterized by a toxigenic bloom, and that commercially important fish species from the lake accumulate toxic MCYST in tissues relevant to human consumption. As such, this system may represent an ideal model of the trophic transfer of MCYSTs, and its relevance to human and environmental health.
Fecundity and Survival Advantages of an Exotic Gastropod Compared to a Native Species by Verónica Núñez, División Zoología Invertebrados, Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Argentina, American Malacological Bulletin 29(1-2):95-103. 2011
Abstract. In artificial lakes of recent origin in the north of the Buenos Aires Province, the European Tadpole snail (Physa acuta) was among the first species colonizing those environments, together with the native Pomacea canaliculata. Elsewhere in Argentina, the exotic snail Physa acuta is predominant in environments previously inhabited by the native species Stenophysa marmorata raising the question of whether this could have occurred because of differences in survival or reproductive strategies. To analyze the life cycle of these two species, I used the horizontal—life-table method and considered the number and proportion of viable of eggs per oviposition. Although both species suffered a high degree of mortality during the first weeks after oviposition, both the rate and the force of mortality was much greater during the reproductive period, so that the survival curve was not as markedly concave as with other gastropods. Physa acuta survived longer than S. marmorata, began its reproductive period earlier, and had a longer and more continuous reproductive stage. The number of ovipositions per snail was not different between the two species; but since the mean number of eggs per oviposition was higher in P. acuta, fecundity was likewise higher. The increase in fecundity was accompanied by an enhancement of the mortality rate in S. marmorata. The percentage of viable eggs was higher in P. acuta than in S. marmorata, but fecundity increased with age in both species. Life expectancy, reproductive value, and net reproductive rate were higher in P. acuta. The success of the exotic species P. acuta in the native habitat of S. marmorata could be explained in part by the former’s earlier sexual maturation, higher reproductive potential, and greater longevity. Further field and laboratory studies are needed to demonstrate the existence of interspecific competition between these two gastropods.
Pomacea canaliculata (Mollusca, Gastropoda) in Patagonia: potential role of climatic change in its dispersion and settlement by DARRIGRAN, G.; DAMBORENEA, C. and TAMBUSSI, A., Braz. J. Biol. [online]. 2011, vol.71, n.1, March 28, 2011
Abstract. Pomacea canaliculata (Lamarck, 1822) (Mollusca Gastropoda) shows a large native distribution range in South America, reaching as far south as 37º S (Buenos Aires, Argentina). This species was deliberately introduced into Southeast Asia around 1980 and subsequently underwent a rapid intentional or accidental dispersal into many countries in the region. It was also introduced into North and Central America and Hawaii. In this contribution we record the presence of P. canaliculata in Patagonia, assessing the possible influence of climatic change in the new establishment of this species there. Three samplings (between September 2004 and April 2005) were carried out at 38º 58′ 20.2″ S-68º 11′ 27.3″ W. In the sampling we found two adult specimens of P. canaliculata and numerous egg clutches. Pomacea canaliculata is naturally distributed in the Plata and Amazon Basins. The southern boundary of this species has been established as the isotherms of 14 ºC and 16 ºC in Buenos Aires province, and precipitations of 900 to 600 mm/year. This study also analyzed variations in annual temperature and precipitation in Patagonia. Average temperatures show an increase over the years, although not constantly. Important modifications in precipitation regime in northern Patagonia, triggered by global climatic changes, could be beneficial for the settlement of populations of P. canaliculata in this new area, where precipitation increased enough to reach values similar to those in the southernmost area of distribution of this species.
CONSUMPTION, SURVIVAL AND GROWTH IN THE INVASIVE FRESHWATER SNAIL POMACEA CANALICULATA: DOES FOOD FRESHNESS MATTER? By Jian-Wen Qiu, Man Ting Chan, King Lun Kwong and Jin Sun, Department of Biology, Hong Kong Baptist University, Hong Kong, P. R. China, J. Mollus. Stud. (2011), March 19, 2011
Abstract. Understanding factors that determine the fitness of invasive species may help us predict their spread and impact. Previous studies of the survival, growth and reproduction of Pomacea canaliculata, a freshwater apple snail native to South America now widely spread in Asia, North America and Hawaii, have emphasized the use of fresh leaves as food. We compared the consumption and growth of P. canaliculata reared on fresh and decaying leaves of three species of macrophytes with contrasting content of phenolics (general plant defense chemicals) and nutrients. We conducted 1-day consumption assays using adult snails and a 1-month survival and growth experiment using snails of various sizes. Our results showed that the consumption, survival and growth of P. canaliculata were determined by plant nutrients and phenolics, rather than plant freshness. For Murdannia nudiflora, a species with low phenolic content, fresh leaves with high nitrogen content were more palatable and valuable for growth than decaying leaves with low nitrogen content. Survival was high and not different between the fresh and decaying leaf treatments. For Myriophyllum aquaticum, decaying leaves with moderate nitrogen and low phenolic contents were more palatable and valuable for snail survival and growth than fresh leaves with high nitrogen and high phenolic contents. For Polygonum barbatum, a species with low nitrogen and medium phenolic contents, both fresh and decaying leaves were unpalatable, resulted in low snail survivorship, and did not support snail growth. The results thus indicate that P. canaliculata can utilize both fresh and decaying leaves of adequate levels of nutrients and low levels of phenolics. This dietary flexibility may have contributed to its successful colonization of many types of freshwater wetlands in regions where high-quality fresh leaves are not available throughout the year.
Prime waterfront real estate: Apple snails choose wild taro for oviposition sites by Colin H.Kyle1, 2, Alexis W. KROPF 2, Romi L. BURKS2: 1 Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA, 2 Department of Biology, Southwestern University, Georgetown, TX 78626, USA; Current Zoology 57 (5): –, 2011].
Abstract. While difficult to prevent introductions, scientific research can help guide control efforts of exotic, invasive species. South American island apple snails Pomacea insularum have quickly spread across the United States Gulf Coast and few control measures exist to delay their spread. Usually occupying cryptic benthic habitats, female apple snails crawl out of the water to deposit large, bright pink egg clutches on emergent objects. To help identify the most likely place to find and remove clutches, we conducted four lab experiments to investigate what specific object qualities (i.e. material; shape and height; plant species; natural and artificial) attracted P. insularum females to lay clutches. In our fourth experiment, we specifically examined the relationship between female size and reproductive output. To further understand reproductive output, we quantified experimental clutch characteristics (height above water, dimensions, mass, approximate volume, number of eggs, hatching efficiency). Pomacea insularum females laid more clutches on plant material, chose round over flat surfaces and failed to differentiate between tall and short structures. In comparison to a common native plant in the eastern US, Pontederia cordata, snails clearly preferred to lay clutches on a widely distributed exotic, invasive plant (wild taro, Colocasia esculenta). Unexpectedly, smaller snails showed higher overall total fecundity as well as more eggs per clutch than larger snails. Therefore, hand removal efforts of large females may not be enough to slow down clutch production. Collectively, our results indicate that conservationists and managers should search emergent plants for P. insularum clutches carefully to guard against established populations.
Evaluation of genetic diversity in the golden apple snail, Pomacea canaliculata (Lamarck), from different geographical populations in China by inter simple sequence repeat (ISSR) by Shengzhang Dong1, Xuping Shentu1, Yinyin Pan1, Xu Bai1, Xiaoping Yu1* and Huadi Wang2, 1Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Sciences, China Jiliang University, Hangzhou 310018, China. 2Bureau of Plant Protection and Quarantine, Agricultural Department of Zhejiang Province, Hangzhou 310020, China. African Journal of Biotechnology Vol. 10 (10), pp. 1777-1783, 7 March, 2011
Abstract. The genetic diversity of Pomacea canaliculata, collected from Los Banos (LB) in Philippines and Yuyao (YY), Taizhou (TZ), Fuzhou (FZ), Guangzhou (GZ), Nanning (NN), Kunming (KM) in China, was studied by using the inter simple sequence repeat (ISSR) technique. A total of 498 loci from 140 individuals were amplified with four selected ISSR primers and the percentage of polymorphic loci was 87.35%. At the species level, the Nei’s gene diversity (H) was 0.3805 and the Shannon information diversity index (I) was 0.5607. A relatively high level of genetic differentiation among populations was detected based on Nei’s gene diversity analysis (Gst = 0.2001) and analysis of molecular variance (AMOVA) analysis (Φst = 0.0824), indicating the vast majority of genetic variation that occur within the populations. The limited genetic distance (0.0793) and correlation between genetic distance and geographic distance matrices (r = 0.5638, P > 0.5) indicated that, there was no significant geographic heterogeneity among these populations.
Herbivore Preference for Native vs. Exotic Plants: Generalist Herbivores from Multiple Continents Prefer Exotic Plants That Are Evolutionarily Naïve by Wendy E. Morrison and Mark E. Hay, School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America, PLoS ONE 6(3): e17227, 2011
Abstract. Enemy release and biotic resistance are competing, but not mutually exclusive, hypotheses addressing the success or failure of non-native plants entering a new region. Enemy release predicts that exotic plants become invasive by escaping their co-adapted herbivores and by being unrecognized or unpalatable to native herbivores that have not been selected to consume them. In contrast, biotic resistance predicts that native generalist herbivores will suppress exotic plants that will not have been selected to deter these herbivores. We tested these hypotheses using five generalist herbivores from North or South America and nine confamilial pairs of native and exotic aquatic plants. Four of five herbivores showed 2.4–17.3 fold preferences for exotic over native plants. Three species of South American apple snails (Pomacea sp.) preferred North American over South American macrophytes, while a North American crayfish Procambarus spiculifer preferred South American, Asian, and Australian macrophytes over North American relatives. Apple snails have their center of diversity in South America, but a single species (Pomacea paludosa) occurs in North America. This species, with a South American lineage but a North American distribution, did not differentiate between South American and North American plants. Its preferences correlated with preferences of its South American relatives rather than with preferences of the North American crayfish, consistent with evolutionary inertia due to its South American lineage. Tests of plant traits indicated that the crayfish responded primarily to plant structure, the apple snails primarily to plant chemistry, and that plant protein concentration played no detectable role. Generalist herbivores preferred non-native plants, suggesting that intact guilds of native, generalist herbivores may provide biotic resistance to plant invasions. Past invasions may have been facilitated by removal of native herbivores, introduction of non-native herbivores (which commonly prefer native plants), or both.
Gender-Based Differences in Florida Apple Snail (Pomacea paludosa) Movements byPatricia L. Valentine-Darby1, Philip C. Darby2* & H.
Franklin Percival3 ,1 The Pomacea Project, 1765 East Nine Mile Road, Suite 1, #369, Pensacola, Florida,2 Department of Biology, University of West Florida,
Pensacola, Florida,3 Florida Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, University of Florida, Gainesville, Florida, Malacologia 54(1-2):109-118. 2011, February 5, 2011
Abstract. Gastropod movements have been studied in the context of habitat selection, finding food and mates, and avoiding predation. Many of these studies were conducted in the laboratory, where constraints on spatial scale influence behavior. We conducted a field study of Florida apple snail (Pomacea paludosa) movements using telemetry. We hypothesized that Florida apple snail movements were driven by reproductive activity, and that gender differences would be evident. We documented male and female directions and distances traveled. We also conducted a trapping study that included conspecific bait to test if the presence of females attracted more males as measured by M:F ratios in traps. The greatest distances traveled were by males, and males were more likely to maintain a consistent bearing compared to females. Male distances peaked in what typically corresponds to peak breeding season. M:F ratios in traps were positively associated with reproductive activity in the study population as measured by egg cluster counts. Conspecific bait had no effect on the number of males or females captured. However, if a female crawled into the trap, we observed greater numbers of males compared to those with no trapped females. Males may have tracked females to increase mating encounters, following slime trails, as seen in other aquatic (including other Pomacea) snails. The capacity for mate finding has implications for reproductive success in the relatively low density populations often seen for Pomacea paludosa.
Slow, but steady: dispersal of freshwater mollusks by Heike Kappes and Peter Haase, Department of Limnology and Conservation, Senckenberg Research Institute and Natural History Museum, Gelnhausen, Germany, Aquatic Sciences –Research Across Boundaries, Springerlink, February 2011
Abstract. Molluscs are the proverbial examples of slow movement. In this review, dispersal distances and speed were assessed from literature data. Active upstream movement can occur both individually and in groups; and depends on traits such as size, sex and reproductive status, and on external factors such as flow velocity, temperature, sediment structure, and food availability. The potential for active dispersal follows the sequence Pulmonata > Prosobranchia > Bivalvia, although data for Pulmonata originated from short-term experiments that likely overestimated dispersal capabilities. Active upstream movement may be 0.3 to 1.0 km per year for most snails and is probably well below 0.1 km per year for bivalves. Natural passive upstream dispersal increases the range 10-fold (snails) to 100-fold (bivalves), and anthropogenic vectors can increase upstream dispersal more than 100-fold (snails) to 1000-fold (bivalves). Three km seems to be the maximal within-stream distance at which many species display regular population mixing, and at which re-colonization or successful restoration can be expected within 3–10 years. Lateral dispersal between unconnected water bodies is passive and mostly known from observational reports, but potential distances depend on vectors, climate and geomorphology. In general, active dispersal seems insufficient to furnish a compensatory mechanism, e.g., for the rate of projected climate change. We provide an overview on dispersal strategies in the light of applied issues. More rigorous field surveys and an integration of different approaches (such as mark-recapture, genetic) to quantify distances and probabilities of lateral dispersal are needed to predict species distributions across space and time.
Comparison of Major Immunoglobulins Intrathecal Synthesis Patterns in Ecuadorian and Cuban Patients with Angiostrongyliasis by Bárbara Padilla-Docal, Alberto J. Dorta-Contreras*, Juan M. Moreira, Luiggi Martini-Robles, Jenny Muzzio-Aroca, Fernando Alarcón, María Esther Magraner-Tarrau, AND Raisa Bu-Coifiu-Fanego Laboratorio Central de Líquido Cefalorraquídeo(LABCEL), Facultad de Ciencias Médicas Dr. Miguel Enríquez,Universidad de Ciencias Médicas de La Habana, Cuba; Direcciónde Control y Mejoramiento de la Salud Pública, Ministeriode Salud Pública, Quito, Ecuador; Departamento de Parasitología,Instituto Nacional de Higiene Dr. Leopoldo Izquieta Perez, Guayaquil,Ecuador; Servicio de Neurología, Hospital Eugenio Espejo,Quito, Ecuador, Am. J. Trop. Med. Hyg., 84(3), 2011, pp. 406-410
Abstract: Angiostrongylus cantonensis meningitis was first reported inCuba in 1981, and it was recently reported in South America.The aim of this paper is to evaluate the intrathecal immunoglobulinsynthesis patterns from Cuba’s and Ecuador’s patients with angiostrongyliasis;8 Ecuadorian patients from two different outbreaks and 28 Cubanpatients were studied. Simultaneous blood and cerebrospinalfluid simples were taken. Immunoglobulin (Ig) A, IgM, IgG, andalbumin were quantified by radial immunodiffusion. CorrespondingReibergrams were applied. A three-Ig pattern was the most frequentin the two groups, but IgM was presented in all Ecuadorian youngmature patients; however, in the Cuban children, only 12 of28 patients had intrathecal IgM, but about 90% had an IgA andIgG synthesis at time of later puncture. This indicates that,with a larger amount of parasites ingested, clinical symptomsare more severe, and a higher frequency of intrathecal IgM synthesiscould be observed. This is discussed as a similarity with theintrathecal IgM synthesis in African trypanosomiasis.
LINKAGE OF COLD HARDINESS WITH DESICCATION TOLERANCE IN THE INVASIVE FRESHWATER APPLE SNAIL, POMACEA CANALICULATA (CAENOGASTROPODA: AMPULLARIIDAE) byTakashi Wada and Keiichiro Matsukura, J. Mollus. Stud. (2011), Published online: February 18, 2011
Abstract. Linkage between cold hardiness and desiccation tolerance was examined in an invasive freshwater apple snail, Pomacea canaliculata, collected from locations in three different climatic zones. Snails collected from temperate Kyushu, Japan, showed enhanced cold hardiness after cold acclimation, and cold-tolerant snails survived longer after exposure to desiccation than cold-intolerant snails without cold acclimation. Progenies of tropical snails collected from Luzon and Mindanao, the Philippines, which had never experienced cold weather revealed the same response as Japanese snails to cold stress: enhancement of cold hardiness after cold acclimation. Cold-tolerant snails from tropical populations also attained better survivorship under desiccation conditions. Thus, linkage of tolerance between cold weather and desiccation appears to be a general feature of P. canaliculata. Cold hardiness of snails before and after cold acclimation, respectively, did not differ among the three populations from temperate and tropical regions. A trend was found for snails from Mindanao, in the tropical rainforest climatic zone (having a milder dry season), to be less desiccation-tolerant than snails from Kyushu and Luzon, having a colder or more severe dry season.
The emergence of angiostrongyliasis in the People’s Republic of China: the interplay between invasive snails, climate change and transmission dynamics By LV, S., ZHANG, Y., STEINMANN, P., YANG, G.-J., YANG, K., ZHOU, X.-N. and UTZINGER, 1 1. Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland 2. University of Basel, Basel, Switzerland 3. National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China, 4 Jiangsu Institute of Parasitic Diseases, Wuxi, China, Journal of Freshwater Biology, February 11, 2011
1. Only few freshwater snail species transmit the rat lungworm Angiostrongylus cantonensis, which is partially explained by the low likelihood of contact between snails and infected rat faeces. The snail Pomacea canaliculata was introduced into China in 1981 and has become the key intermediate host for A. cantonensis. Thus far, the snail has been recorded in 13 provinces of southern China.
2. We developed a biological model and assessed potential impacts of climate change on the distribution of P. canaliculata and hence the transmission of A. cantonensis. Mean January temperature and snail generation intensity (generation number) were identified as the key factors determining P. canaliculata distribution. Our models predict an increase of 56.9% for the ‘spread’ and a decrease of 40.9% for the ‘establishment’ regions (‘spread’ and ‘establishment’ defined according to a national sampling survey) by the 2030s relative to the present day.
3. Key determinants of A. cantonensis transmission were identified as the generation intensity in the intermediate host, the longevity of A. cantonensis-infected rats and the dormant period of P. canaliculata. Transmission of A. cantonensis occurs only in areas where the snail’s dormant period is <173.2 days. The potential endemic area of A. cantonensis is predicted to double by the 2030s relative to the present day.
4. The tight fit of our model predictions with data derived from a national sampling survey suggests that biological models hold promise for assessing potential impacts of climate change on infectious diseases once key determinants have been established. Geographical variation analysis may offer an approach to identify areas prone to the spread of vectors, intermediate hosts and parasites in a future warmer China and elsewhere.
Epidemiological survey of Angiostrongylus cantonensis in the west-central region of Guangdong Province, China by Daixiong Chen, Yun Zhang, Haoxian Shen, Yongfang Wei, Di Huang, Qiming Tan, Xianqi Lan, Qingli Li, Zecheng Chen and Zhengtu Li, et al., Parasitology Research, January 12 2011
Abstract. The study was to understand the Angiostrongylus cantonensis infectious situation of rodent definitive host, snail intermediate host, and local residents in the west-central region of Guangdong Province in China. The snails Achatina fulica and Pomacea canaliculata collected from the survey place were digested with artificial gastric juice, and the third-stage larvae of A. cantonensis in the snails were examined under microscope. The heart and lung of rats captured from the survey place were taken to check the adult of A. cantonensis. The questionnaire surveys related to the infection of A. cantonensis were taken in local residents randomly selected, and the IgG antibody against A. cantonensis was tested in those residents with enzyme-linked immunosorbent assay (ELISA). A total of 1,391 rats including eight kinds of rats, such as Rattus norvegicus, Rattus flavipectus, Bandicota indica, Rattus sladeni, Mus musculus, Rattus rattoides, Suncus Murinus, and Rattus confucianus, were examined and 132 of them were infected by A. cantonensis, with an average infection rate of 9.49% and a mean intensity of A. cantonensis in infected rats was 9.39. A total of 3,184 snails A. fulica and 3,723 snails P. canaliculata were detected. The average infection rates of them were 25.03% (797/3,184) and 6.50% (242/3,723), respectively. There were 180 positive samples of IgG antibody against A. cantonensis in 1,800 serum samples of the residents, with a positive rate of 10.00%. The west-central region of Guangdong Province is the natural focus of A. cantonensis. In comparison with the investigation results in other regions of China, the infection rate of rat definitive host is at the middle level; in the intermediate host, the infection rate of snail A. fulica is above the middle level, and the infection rate of snail Pomacea canaliculata is below the middle level. Some local residents had already been infected by A. cantonensis or at the risk of being infected.
Study on Occurrence, Damage and Control of Golden Apple Snail, Pomacea canaliculata (Lamarck), in Paddy Fields of Hubei Province By WAN Peng1, CHU Shi-hai1, WU Huai-heng1, HUANG Min-song1, JIANG Gan-ming2 (1. Hubei Key Laboratory of Crop Diseases, Insect Pests and Weeds control/Institute of Plant Protection, Soil and Fertilizer, Hubei Academy of Agricultural Sciences, Wuhan 430064; 2. Huanggang Station of Plant Protection, Huanggang 438000, Hubei, China), Hubei Agricultural Sciences, December 2010.
Abstract. Occurrence rule, damage situation and control technique of golden apple snail, Pomacea canaliculata, in paddy fields of Yingshan, Hubei Province, had been studied. The results suggested that there was one generation for golden apple snail one year. It feeds on rice and weed, and overwinters under soil or in spas. Golden apple snail usually causes serious damage to rice in the vegetative stage which is between transplanting and booting. Damage to rice is positively correlated with the egg density, numbers of the young or mature of golden apple snail. The experiments with spraying insecticides indicated that five chemicals supplied showed high efficacy to the golden apple snail.
Molluscicidal activity of Sapindus mukorossi and Terminalia chebula against the freshwater snail Lymnaea acuminata by Aparna Upadhyaya and D.K. Singh Malacology Laboratory, Department of Zoology, DDU Gorakhpur University, Gorakhpur 273 009, UP, India, 7 January 2011. doi:10.1016/j.chemosphere.2010.12.066,
Abstract. The molluscicidal activity of the Soapnut Tree (Sapindus mukorossi) and Black Myrobalan Tree (Terminalia chebula) fruit powder against the vector snail Lymnaea acuminata was time and concentration dependent. The molluscicidal activity of T. chebula fruit powder (96 h LC50:93.59 mg L−1) was more pronounced than that of S. mukorossi fruit powder (96 h LC50:119.57 mg L−1). Ethanolic extracts of S. mukorossi and T. chebula fruit powder were more toxic than their other organic solvent extracts. The molluscicidal activity of ethanolic extract of S. mukorossi fruit powder (24 h LC50:2.75 mg L−1) was more effective than the ethanolic extract of T. chebula fruit powder (24 h LC50:124.06 mg L−1). The 96 h LC50 of column-purified fraction of S. mukorossi fruit powder was 5.43 mg L−1 whereas those of T. chebula fruit powder was 7.49 mg L−1. Column, thin layer and high performance liquid chromatography analysis demonstrates that the active molluscicidal component in S. mukorossi and T. chebula is saponin (96 h LC50:1.31 mg L−1) and tannic acid (96 h LC50:1.64 mg L−1), respectively. These plants may be used as potent source of molluscicides against the snail L. acuminata.
The Interactive Effects of Predators, Resources, and Disturbance on Freshwater Snail Populations from the Everglades by C. B. Ruehl, FIU Electronic Theses and Dissertations, Paper 266 (2010)
Summary. Interplay between the positive effects of nutrients, and the negative effects of seasonal drying, predators and their cues limit snail populations in the Everglades. Nutrients emerge as the most important factor because the Everglades, and similar ecosystems, have extraordinarily low phosphorous levels and although periphyton production is high, it is of low nutritional quality. Phosphorous additions lead to increased growth and reproductive rates that ultimately have positive effects on population growth rates. Seasonal drying removes a portion of the snail population annually but they appear to recover quickly due to life history traits enabling them to resist desiccation. Predator effects become important at certain times and places in the Everglades, but do not amount to the chronic effects of low resource quality for snail populations. These findings offer experimental results that bolster data collected through monitoring efforts designed to assess the Comprehensive Everglades Restoration Plan (CERP) and provide insight into the general understanding of the interactive effects of nutrients, seasonality, and predators in structuring populations.
An Aquatic Bal-Chatri for Trapping Snail Kites (Rostrhamus sociabilis) by Peter J. Mahoney1, Kenneth D. Meyer1,*, Gina M. Zimmerman1 and Christopher E. Cattau2, 1 Avian Research and Conservation Institute, 411 NE 7 Street, Gainesville, FL 32601, 2 Florida Cooperative Fish and Wildlife Research Unit, University of Florida, Gainesville, FL 32611, Southeastern Naturalist 9(4):721-730, December 2010
Abstract. The endangered Rostrhamus sociabilis plumbeus (Florida Snail Kite) has been the focus of several ecological studies emphasizing movements between and within wetland fragments. These studies have required the ability to trap and radiotag free-flying adults without significant risk of injury. We developed and tested a safe alternative to previous methods for trapping Snail Kites as part of a comparative study of VHF and satellite telemetry. The aquatic bal-chatri borrows from historical trap designs with modifications for trapping aquatic birds at the surface of the water. It consists of a square PVC frame with a series of parallel flourocarbon stringers and a mesh basket to restrain the lure species. Nooses are attached to the stringers and used to ensnare the toes of a predatory bird. The trap is held afloat by the PVC frame, with the mesh basket, stringers, and nooses positioned just beneath the surface of the water. After determining effective trap placement in relation to perched birds, we captured 11 kites in 13 days with native pomacea paludosa (Florida Apple Snail) and exotic Pomacea insularum (Island Apple Snail) as lures. Our results indicated that the aquatic bal-chatri can be used to target specific Snail Kites and recapture previously trapped individuals. This trap design is a safe, efficient, and low-cost alternative to methods previously used for capturing Snail Kites. Additionally, the aquatic bal-chatri is relatively easy to use and appears to have minimal impact on foraging behavior and breeding performance of Snail Kites.
Weight Gain and Reproduction of Pomacea canaliculata by Nara R. Terra1 & Alois Schäfer2, 1Fundação Estadual de Proteção Ambiental Henrique Roessler, RS – Divisão de Biologia – Porto Alegre – RS – Brasil., 2Fachrichtung Biogeographie – Zentrum für Umweltforschung – Universität des Saarlandes – Saarbrücken – Deutshland, Brasilian Journal of Ecology, 2010
Abstract. Weight gain and reproduction in 40 molluscs, beginning at 86 days of age, were observed during 373 days. The molluscs were kept in aquaria, with reconstituted water. They were weighed once a week and at the beginning of reproductive activity, and egg laying and hatching were followed daily. The Variation
Coefficient as compared with weight gain is as much as 113%, and the females
are larger and heavier than the males. There is no correlation between the size
of the individuals and sexual maturity. The females suffer progressive
decalcification as they lay eggs. The individuals die after completing their
reproductive activity. Observations indicate that this species is appropriate
for toxicological trials, because it is easy to breed in laboratory and costs
little to maintain.
Ultrastructure of radula, gonad and spawn of Pomacea canaliculata(Lamarck) observed with scanning electron microscope by WANG Zhi-gao1,TAN Ji-cai1,LIU Jun1,2,LI Mi1,ZOU Jian-feng3,HE Man-ting4,ZHONG Lang1(1.College of Bio-Safety Scienceand Technology, Hunan Agricultural University,Changsha 410128,China; 2.Hunan Environment Biological Polytechnic, Hengyang 421005,China; 3.Center of Analytical Service Hunan Agricultural University, Changsha 410128,China; 4.Department of Agriculture Environmental Monitoring Station of Hunan Province, Changsha 410005,China), Guangdong Agricultural Sciences, 2010-10
Abstract. The ultrastructure, especially the radula, spermary, ovary and spawn of Pomacea canaliculata were observed and analyzed under scanning electron microscope. The radula of Pomacea canaliculata(Lamarck) was a taenoglossate radula, dentition formula(2·1·1·1·2)×35, the cusp of teeth was sharp. Structure of the spermary was simple, did not have seminiferous tubule. Spermatogenic cells attach on the branches of the connective tissue through basement membranes. Lumen of spermary are reticulated and interlinked with each other. All levels of globular spermatids are distributed in the cavity of trabecular connective tissue. Female snails ovary was large, pink dendrites, close to the digestive gland. The main structure of ovary is follicle. Ocytes grow and mature in the follicle. The observed oocytes were well-distributed and had no significant differences in the size. Irregular soft liquid dispersed on the surface of the 7 d spawn, compared with the less on the 14 d spawn, but there were ups and downs of the drape and fissure on the latter.
The Role of the Proteinase Inhibitor Ovorubin in Apple Snail Eggs Resembles Plant Embryo Defense against Predation by Marcos Sebastián Dreon, Santiago Ituarte, Horacio Heras, Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET-Universidad Nacional de La Plata, La Plata, Argentina, PLoS ONE 5(12), December 3, 2010
Background. Fieldwork has thoroughly established that most eggs are intensely predated. Among the few exceptions are the aerial egg clutches from the aquatic snail Pomacea canaliculata which have virtually no predators. Its defenses are advertised by the pigmented ovorubin perivitellin providing a conspicuous reddish coloration. The nature of the defense however, was not clear, except for a screening for defenses that identified a neurotoxic perivitellin with lethal effect on rodents. Ovorubin is a proteinase inhibitor (PI) whose role to protect against pathogens was taken for granted, according to the prevailing assumption. Through biochemical, biophysical and feeding experiments we studied the proteinase inhibitor function of ovorubin in egg defenses.
Methodology/Principal Findings. Mass spectrometry sequencing indicated ovorubin belongs to the Kunitz-type serine proteinase inhibitor family. It specifically binds trypsin as determined by small angle X-ray scattering (SAXS) and cross-linking studies but, in contrast to the classical assumption, it does not prevent bacterial growth. Ovorubin was found extremely resistant to in vitro gastrointestinal proteolysis. Moreover feeding studies showed that ovorubin ingestion diminishes growth rate in rats indicating that this highly stable PI is capable of surviving passage through the gastrointestinal tract in a biologically active form.
Conclusions. To our knowledge, this is the first direct evidence of the interaction of an egg PI with a digestive protease of potential predators, limiting predator’s ability to digest egg nutrients. This role has not been reported in the animal kingdom but it is similar to plant defenses against herbivory. Further, this would be the only defense model with no trade-offs between conspicuousness and noxiousness by encoding into the same molecule both the aposematic warning signal and an antinutritive/antidigestive defense. These defenses, combined with a neurotoxin and probably unpalatable factors would explain the near absence of predators, opening new perspectives in the study of the evolution and ecology of egg defensive strategies.
First report of Angiostrongylus cantonensis in East African Land Snail (Achatina fulica) from Southeast and South Brazil by Arnaldo Maldonado JúniorI, +; Raquel O SimõesI; Ana Paula M OliveiraII; Esther M MottaIII; Mônica A FernandezII; Zilene M PereiraII, III; Simone S MonteiroIII; Eduardo J Lopes TorresV; Silvana Carvalho ThiengoII, ILaboratório de Biologia e Parasitologia de Mamíferos Silvestres Reservatórios, IILaboratório de Malacologia , IIILaboratório de Educação em Ambiente e Saúde , IVLaboratório de Patologia, Instituto Oswaldo Cruz-Fiocruz, Av. Brasil 4365, 21040-900 Rio de Janeiro, RJ, Brasil, VLaboratório de Biologia de Helmintos Otto Wucherer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil,Mem. Inst. Oswaldo Cruz vol.105 no.7, Rio de Janeiro, Nov. 2010
Abstract. The rat lungworm Angiostrongylus cantonensis is a worldwide-distributed zoonotic nematode that can cause human eosinophilic meningoencephalitis. Here, for the first time, we report the isolation of A. cantonensis from Achatina fulica from two Brazilian states: Rio de Janeiro (specifically the municipalities of Barra do Piraí, situated at the Paraiba River Valley region and São Gonçalo, situated at the edge of Guanabara Bay) and Santa Catarina (in municipality of Joinville). The lungworms were identified by comparing morphological and morphometrical data obtained from adult worms to values obtained from experimental infections of A. cantonensis from Pernambuco, Brazil, and Akita, Japan. Only a few minor morphological differences that were determined to represent intra-specific variation were observed. This report of A. cantonensis in South and Southeast Brazil, together with the recent report of the zoonosis and parasite-infected molluscs in Northeast Brazil, provide evidence of the wide distribution of A. cantonensis in the country. The rapid spread of A. fulica over the country (now having reached 24 out of 26 Brazilian states and the Federal District) is likely contributing to the dispersion of the parasite. This phenomenon is described in the literature as one of the primary causes of the spread of rat lungworm. The need for efforts to better understand the role of A. fulica in the transmission of meningoencephalitis in Brazil and the surveillance of molluscs and rodents, particularly in ports, is emphasized.
Evolutionary and Functional Significance of Lengthy Copulations in a Promiscuous Apple Snail, Pomacea canaliculata by Silvana Burela and Pablo R. Martín, Departamento de Biología, Bioquímica y Farmacia, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional del Sur, San Juan 670, 8000 Bahía Blanca, Argentina, J. Mollus. Stud. (2010), November 26, 2010
Abstract. Peculiar adaptations of the dioecious freshwater snails belonging to the family Ampullariidae have recently been recognized as important, albeit neglected, models for evolutionary ecology studies. A review of the literature, mostly reports from unsystematic observations under laboratory conditions, revealed considerable variation (38 min to 20 h) in the duration of copulation in this family, both at inter- and intraspecific levels. The aims of our study were to investigate if the lengthy copulations of Pomacea canaliculata occur naturally in the wild and if a significant part of the copulation duration was to accomplish genital connection or to impede the access of other males, rather than being necessary solely for sperm transfer. The effect of single vs repeated copulations in terms of female reproductive output, and the effect of some proximate factors (male size, mating status, time of the day and prowler males) on the duration of copulation were also evaluated. Our field results indicate that lengthy copulations previously reported for P. canaliculata were not an artefact. The laboratory evidence obtained indicates that the completion of the genital connection or a preinsemination mate guarding can account for only 20% of the copulatory period and that there is no postinsemination guarding. Most of the copulation time is apparently necessary to transfer an amount of sperm that will ensure the fertilization of the thousands of ova produced during the entire lifetime of females. Our laboratory experiments also showed that there was no effect of male size, the time at which copulation begins, the mating status of snails or of the presence of prowler males on the duration of copulation.
Investigation of the foci of Angiostrongyliasis in Yunnan province by WANG Li-bo, DU Zun-wei, JIANG Jin-yong, WU Fang-wei, Yunnan Institute of Parasitic Diseases, Puer 665000, Yunnan Province, China, Chines Journal of Vector Biology and Control 2010, 21(5) 496-497
Abstract. Objective: To determine the distribution of the foci of Angiostrongyliasis in parts of Yunnan province, providing the basis for prevention and control of its infection. Methods: The investigation was conducted in accordance with the requirements of the survey program on Angiostrongylus cantonensis issued by the Ministry of Health. Results: A total of 7 intermediate hosts of A. cantonensis were found at the sampling sites. Pomacea canaliculata was distributed in 13 of the 19 surveyed counties, accounting for 68.42%. Of the 3874 captured snails, P. canaliculata accounted for 51.83% and Achatina fulica accounted for 6.56%. The positive infection rates of 3rd instar larvae of A. cantonensis found in Jinghong and Mengla counties were 0.56% and 0.26%, respectively. Conclusion: The natural foci of Angiostrongyliasis are present in Yunnan.
Progress in integrated control of Pomacea canaliculata, intermediate host of Angiostrongylus cantonensis by WEI Ji-qian1, MO Jian-chu2, HONG Wen-ying1, XU Wen1, XU Feng-xian1 1. Hangzhou General Station of Plant Protection and Soil Fertilizer, Hangzhou 310020, Zhejiang Province, China; 2. Urban Entomology Research Center, Institute of Insect Sciences，Zhejiang University, Chinese Journal of Vector Biology and Control 2010, 21(5) 512-514.
Abstract. Angiostrongylus cantonensis is an animal parasite that also invades the human body. Living in the central nervous system, it may cause eosinophilic meningoencephalitis (eosinophilic meningoencephalitis due to A. cantonensis). At present, the disease is mainly seen in the Asia/Pacific region, particularly Southeast Asian countries and China’s southern provinces. Pomacea canaliculata is a major intermediate host of A. cantonensis. In recent years, outbreaks of eosinophilic meningoencephalitis due to A. cantonensis in Wenzhou city, Zhejiang province and Changle city, Fujian province were wholly caused by consumption of P. canaliculata. However, prevention and control of P. canaliculata is currently limited to simple physical, agriculture and chemical means, and an effective system of integrated control techniques has yet to be found. This paper mainly introduces the domestic and foreign advances in prevention and treatment of P. canaliculata in recent years.
Images in Clinical Tropical Medicine Myelitis Caused by Infection of Angiostrongylus cantonensis by Zongli Diao , Chenghong Yin ,* and Erhu Jin, Beijing Tropical Medicine Research Institute, Beijing Friendship Hospital, Capital Medical University, Beijing, China; Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China Am. J. Trop. Med. Hyg., 83(6), 2010, pp. 1176–1177
A 32-year-old man presented to our hospital on July 5, 2006, after the onset of headache, paresthesias (tingling, pricking, or numbness) of the left upper limb for 10 days, and weakness for 7 days before admission. He had eaten an inadequately cooked Pomacea canaliculata20 days previously. Laboratory testing indicated a normal white blood cell count of 6,700/mm 3 with mild eosinophilia of 7.8% (523/mm 3 ). A lumbar puncture test showed an opening pressure of 220 mm H 2 O and 160 cells with 23% eosinophils, and cerebrospinal fluid (CSF) cultures were negative. We detected the circulating antigens (CAg) of Angiostrongylus cantonensisby double antibody sandwich enzyme-linked immunosorbent assay (ELISA), and they tested positive. This method had a high sensitivity (86.4%), and no cross-reactions with sera from patients with many other parasites were observed. Therefore, the result was helpful for diagnosis. Spinal magnetic resonance imaging (MRI) showed a lesion with high signal intensity in the cervical spinal cord on both sagittal and transverse T2-weighted imaging (T2WI) at 9 days after admission. On the basis of history, clinical presentation, and examinations, a diagnosis of angiostrongyliasis was made, and the patient was treated with a combination of albendazole and dexamethasone. Symptoms of headache and paresthesia resolved within 14 days, and spinal-cord lesions completely resolved by a 1-month follow-up.
ANALYSIS ON THE INFECTION OF ANGIOSTRONGYLUS CANTONENSIS IN WATER SYSTEM OF PEARL RIVER DELTA AND COASTAL AREAS OF GUANGDONG by HUANG Shao-yu,DENG Zhuo-hui,ZHANG Qi-ming,et al.(Guangzhou Center for Disease Prevention and Control,Guangzhou 510300,China), Modern Preventive Medicine 2010-18
[Objective] To get acquainted with the distribution and infection of host and intermediate host of Angiostrongylus cantonensis in Pearl River Delta and coastal areas of Guangdong.[Methods] An examination of pathogen has been conducted by collecting living Pomacea canaliculata,Achatina fulica,fresh rat dung and catching rats in Pearl River Delta and coastal areas in the east,middle and west of Guangdong,3-4 countries of which were selected by their geographic location.[Results] We investigated the data from 12 countries(citiesand communities)in Pearl River Delta and coastal areas in the east,middle and west of Guangdong province from 2006 to 2008,these areas were found the propagating of Pomacea canaliculata and Achatina fulica.The average infection rate of Angiostrongylus cantonensis was 6.83%and 16.89%,respectively,and the latter was significantly higher than that of the former(χ2 = 65.44,P﹤0.01).Pearl River Delta was reported to have the highest infection rates of Pomacea canaliculata and Achatina fulica,coastal areas in the east of Guangdong province ranked the second,and west of Guangdong province ranked the last.The highest larva density of Pomacea canaliculata was found to be 110 pcs per one and Achatina fulica 12 000 pcs per one.Infection rate has something to do with the propagating environment and the size of whorl.The infection rates ofAchatina fulica were respectively 40% and 13.64%(χ2 = 8.20,P﹤0.005)for large size(≥70 g)and mid size(﹤70 g)and Pomacea canaliculata were 17.50% and 4.08%(χ2 = 3.88,P﹤0.05)for large size(≥30 g),and mid size and small size(﹤30 g).The Pomacea canaliculata from a drain and the Achatina fulicafrom a bosk were proved to have the top infection rates,which were 8.14%(18 /221)and 31.58%(18 /57).Sewer rat was found to be the final host with the highest infection rate(14.79%,21 /142)and Angiostrongylus cantonensis were also found in other kinds of rats.[Conclusion] Rats,Pomacea canaliculata, and Achatina fulica which act as the final host and intermediate host of Angiostrongylus cantonensis have been found widespread in Pearl River Delta and coastal areas causing serious infection.
Knowledge, attitudes and practices of farmers on rodent pests and their management in the lowlands of the Sierra Madre Biodiversity Corridor, Philippines by Alexander M. Stuarta, , , Colin V. Prescotta, Grant R. Singletonb and Ravindra C. Joshic, 1a School of Biological Sciences, The University of Reading, Berkshire RG6 6AS, UKb International Rice Research Institute, DAPO Box 7777, Manila, Philippines, c Department of Agriculture – Philippine Rice Research Institute, Muñoz Science City, Nueva Ecija 3119, Philippines, Crop Protection (November 2010)
Abstract. A survey of the knowledge, attitudes and practices (KAP) of 100 rice farmers and 50 coconut farmers was conducted in the coastal lowland agro-ecosystems of the Sierra Madre Biodiversity Corridor, Luzon, Philippines to identify current rodent management practices and to understand the extent of rat damage and the attitudes of farmers to community actions for rodent management. Pests were most commonly listed as one of the three most important rice and coconut production constraints. Other major crop production constraints were typhoons and insufficient water. Farmers consider rats to be the major pest of coconut and of rice during the wet season rice crop, with average yield losses of 3.0% and 13.2%, respectively. Rice and coconut farmers practised a wide range of rodent management techniques. These included scrub clearance, hunting and trapping. Of the 42 rice farmers and 3 coconut farmers that applied rodenticides to control rodents, all used the acute rodenticide, zinc phosphide. However, only ten rice farmers (23.8%) applied rodenticides prior to the booting stage and only seven farmers (15.6%) conducted pre-baiting before applying zinc phosphide. The majority of farmers belonged to farmer organisations and believed that rat control can only be done by farmers working together. However, during the last cropping season, less than a third of rice farmers (31.2%) applied rodent management as a group. In order to reduce the impact of rodents on the farmers of the coastal lowlands of the Sierra Madre Biodiversity Corridor, integrated management strategies need to be developed that specifically target the pest rodents in a sustainable manner, and community actions for rodent management should be promoted.
E-commerce of freshwater aquarium fishes: potential disseminator of exotic species in Brazil by André Lincoln Barroso de Magalhães1* and Claudia Maria Jacobi2 1Programa de Pós-graduação em Ecologia, Conservação e Manejo de Vida Silvestre, Universidade Federal de Minas Gerais, Centro Universitário União de Negócios e Administração Ltda., Brazil. 2 Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais., Brazil. *Author for correspondence. E-mail: email@example.com Acta Scientiarum. Biological Sciences Maringá, v. 32, n. 3, p. 243-248, 2010
ABSTRACT. The availability of freshwater aquarium fish species for sale was surveyed from July 2005 to June 2006 in Brazilian electronic commerce and the Orkut website. São Paulo was the leading state regarding virtual shops, auctions on Arremate/Mercado Livre, and hobbyists on Orkut, with 52, 44 and 46%, respectively. The Southeast and South regions led the offer of pest species such as C. carpio, C.auratusand P. reticulata. Among the 207 species for sale, 14 species considered potential pests were identified, contrasting with only one page that warned about the dangers of aquarium dumping. The easy access to fish (especially the potential pest species) through e-commerce and Orkut, together with the low total price (unitary value + shipping and handling ranging from US$ 17.67 to 30.39), and fast interstate delivery (two-four days on average) confirm the widespread e-commerce accessibility and its high dispersal potential via postal services and home hobbyists trade. It is imperative to enforce the use of warnings or alert messages in e-commerce about the dangers of biological invasions.
Induced chemical defenses in a freshwater macrophyte suppress herbivore fitness and the growth of associated microbes by Wendy E. Morrison · Mark E. Hay W. E. Morrison, School of Biology, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332, USA e-mail: firstname.lastname@example.org Oecologia, DOI 10.1007/s00442-010-1791-1, October 2010
Abstract. The freshwater macrophyte Cabomba caroliniana induces a chemical defense when attacked by either the crayfish Procambrus clarkii or the snail Pomacea canaliculata. Induction by either consumer lowers the palatability of the plant to both consumers. When offered food ad libitum, snails feeding on non-induced C. caroliniana grew 2.6–2.7 times more than those feeding on induced C. caroliniana. Because snails fed less on induced plants, this could be a behavioral effect (reduced feeding), a physiological effect of the induced metabolites on the consumer, or both. To assess these possibilities, we made artificial diets with lipid extracts of induced versus non-induced C. caroliniana and restricted control snails to consuming only as much as treatment snails consumed. Growth measured as shell diameter was significantly lower on the diet containing extract from induced, as opposed to non-induced, plants; change in snail mass was more variable and showed a similar, but non-significant, trend. Thus, snails may reduce feeding on induced plants to avoid suppression of fitness. The induced defenses also suppressed growth of co-occurring microbes that might attack the plant through herbivore-generated feeding scars. When two bacteria and three fungi isolated from C. caroliniana surfaces were cultured with the lipid extract from induced and non-induced C. caroliniana, both extracts inhibited the microbes, but the induced extract was more potent against three of the five potential pathogens. Thus, induced plant defenses can act against both direct consumers and microbes that might invade the plant indirectly through herbivore-generated wounds.
Wild record of an apple snail in the Waikato River, Hamilton, New Zealand, and their incidence in freshwater aquaria by Kevin J. Collier1,2,3, Nicholas J. Demetras1, Ian C. Duggan1 & Toni M. Johnston1, 1Centre for Biodiversity and Ecology Research, The University of Waikato, Private Bag 3105, Hamilton, New Zealand, 2Environment Waikato, PO Box 4010, Hamilton, New Zealand, New Zealand Natural Sciences (2011) 36: 1-9, 22 (September 22, 2010)
Abstract. We report the discovery of a single specimen of a live apple snail Pomacea diffusa Blume 1957 (Ampullariidae: Prosobranchia), from the Waikato River, Hamilton city, central North Island, New Zealand. This species, along with the congeneric P. insularum, is imported for the aquarium trade, and its occurrence in the river likely stemmed from an aquarium release. A survey of 55 aquaria belonging to 43 hobbyists revealed 27 apple snails, with one owner having 22 snails. Assessment of environmental tolerances and impacts of P. diffusa, based largely on studies of the closely related and commonly confused congener P. bridgesii, suggests that direct habitat impacts by this species are likely to be minor. However, there could be indirect influences on native biodiversity through predation on eggs or competition for food supplies with other detritivorous species if densities were to become high. Water temperatures in the Waikato River below Hamilton (10-23˚C in 2009) may enable released individuals to persist for an extended period, and over summer may exceed the threshold required to enable breeding. However, population establishment would be most likely in locations where water is heated through geothermal influences or industrial cooling water discharges.
Feeding and growth of native, invasive and non-invasive alien apple snails (Ampullariidae) in the United States: Invasives eat more and grow more by Wendy E. Morrison and Mark E. Hay, Georgia Institute of Technology, Atlanta, Georgia, Biological Invasions, September 2010
Abstract. The United States hosts one native and five non-native species of aquatic apple snails (Ampullariidae). All are currently found in or around the Everglades in Florida. Two of these introduced species have devastated wetlands in Southeast Asia, but little is known about how they may impact the Everglades. To evaluate potential impacts of introduced apple snails relative to the native species, we investigated plant species preference, consumption rates, growth rates, and growth efficiencies in five introduced and the single native species across eight native macrophytes common in the Everglades. Three of the non-native snails are invasive, one has shown no tendency to expand, and one appears to have minimal direct impact on macrophytes due to its diet. All snails exhibited similar feeding preferences, with Utricularia sp. being the most preferred, Bacopa caroliniana, Sagittaria latifolia, and Nymphaea odorata being of intermediate preference, and Eleocharis cellulosa, Pontederia cordata, Panicum hemitomon and Typha sp. being least preferred (avoided as foods). Consumption and growth was minimal for P. diffusa on all macrophytes. On Utricularia sp. and Bacopa caroliniana, the invasive species Pomacea insularum and P. canaliculata tended to eat more, grow more, and have higher conversion efficiencies than the native P. paludosa or the non-invasive P. haustrum. These contrasts were more often significant for P. insularum than for P. canaliculata. The greater rates of expansion by the invasive species may derive from their enhanced feeding and growth rates.
New Depths for the Florida Apple Snail, Pomacea paludosa by Jennifer L. Bernatis, School of Natural Resources and Environment, University of Florida, Gainesville, FL, Ellisparia, Volume 12, No. 2, August 2010
The Florida apple snail, Pomacea paludosa, is the only apple snail native in the United States. P. paludosa is found throughout Florida and is the primary food source for the endangered Everglade Snail Kite, Rostrhamus sociabilis plumbeus (Darby, 2005; Kushlan, 1975). The snail was once abundant in many locations throughout Florida, but population numbers have been suspected to be declining in recent years. Reasons for this decline may include environmental perturbations (i.e. pollutants, water levels), destruction of habitat, and establishment of populations of non-native apple snails belonging to the Pomacea canaliculata complex. Darby et al. (2002) suggested P. paludosa exhibits an aversion to water depths greater than 50 cm. Reasons for this include the need to breathe atmospheric air, and the amount of energy required to move up to the water/air interface. Darby (1998) also suggested that the accumulation of unconsolidated organic material may restrict movement into deep water. Reduced food availability, habitat structure, and low levels of dissolved oxygen may also account for the absence of snails in deeper water. However, recent observations and collections of P. paludosa in Apopka Spring may suggest that depth is not a deterrent to the snails.
Apple snails were observed in Apopka Spring over several monthly sampling trips by diver Tom Morris, of Karst Environmental Services (High Springs, FL). In April 2010, snails were collected and identified as P. paludosa. Four snails were removed from the spring vent. Two of the snails were collected at 12.2 m, one at 13.1 m and the last at 14.6 m. The three snails at the lesser depths were all firmly attached to the rocky substrate. The deeper snail was loosely attached and resting on the substrate. Temperature in the spring was 23.3o C and the water was clear. There was no vegetation in the spring vent and no snail egg masses were observed near emergent vegetation around the boil. Although flow at the spring vent was measured at 20 cfs, the flow at the location of the snails was 1-1.5 cfs. The snails were taken to a laboratory facility and remained in good condition until July 2010. Water level requirements of apple snails continue to be of interest as they are the primary food source for the endangered Everglades Snail Kite. However, while the snail may prefer less deep habitat, this finding may provide insight into where the snails are finding refuge in periods of environmental perturbations. Locations with deeper holes, particularly spring systems, where snail populations are presumed reduced or extirpated, need to be surveyed for the presence of snails; as the presence of snails in these locations may be indicative of other water quality problems.
Bioaccumulation of copper and toxic effects on feeding; growth; fecundity and development of pond snail Lymnaea luteola L. by Sangita Dasa and B.S. Khangarot, a, a Ecotoxicology Division, Indian Institute of Toxicology Research (IITR), Council of Scientific and Industrial Research (CSIR), M. G. Marg, Post Box No. 80, Lucknow 226 001, India, Journal of Hazardous Materials, 2010
Abstract. We studied the bioaccumulation and the toxic effects of Cu on survival, number of eggs and eggmasses laying, embryo development, growth, and food consumption in an Indian pond snail, Lymnaea luteola L. exposed for 7 weeks. Copper caused loss of chemoreception, locomotion and inhibited food consumption significantly during 7 weeks of exposure. Food consumption in Cu exposed snails significantly decreased and at 56 and 100 μgL−1, snail stopped feeding activity. Mean number of eggmasses or eggs significantly decreased in Cu concentrations during the 7 week study. The percentage hatching decreased in Cu concentrations but there was more than 95% hatched in control in 10-11 days after spawning. Egg development was completely inhibited at 100 μgL−1, whilst abnormal embryonic development observed at 32 and 56 μgL−1 of Cu. The Cu concentration in tissues increased in Cu treated snails and bioaccumulation factor ranged from 2.3 to 18.7. Snail growth at 5.6 and 10 μgL−1 was reduced by 6.2%, and 16.9%, respectively. The study revealed that snail embryos and adults could be used as in vivo test models for ecotoxicological studies. Findings of present study are helpful for advancing water quality guidelines for protecting aquatic biota.
Seroprevalence of Angiostrongylus cantonensis infection in humans in China by Mu-Xin Chen, Ren-Li Zhang, Lin Ai, Jia-Xu Chen, Shao-Hong Chen, Da-Na Huang, Shi-Tong Gao, Yi-Jie Geng, Xiao-Heng Li, and X.Q. ZHU, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China, Journal of Parasitology (2010)
Abstract. A seroepidemiological survey was carried out in China during 2009-2010 to determine Angiostrongylus cantonensis circulating antigens (CAg) in the Chinese population by the gold immunochromatographic assay, with the objective of elucidating the nation-wide prevalence of angiostrongyliasis in China. A total of 1,730 blood samples was collected and assayed from the general adult population (the ‘general group’) and those involved in aquaculture or processing of snails Achatina fulica and Pomacea canaliculat (the ‘occupational group’) from 5 provinces (Fujian, Hunan, Guangdong, Guangxi, and Zhejiang) and 1 municipal city (Beijing). The overall seroprevalence for the ‘occupational group’ was 7.4% (40/540), which was significantly higher (P<0.001) than that of the ‘general group’ (0.8%, 9/1190). The seroprevalence in males (9.5%) was significantly higher than in females (4.2%) (P<0.05). These results demonstrate that angiostrongyliasis represents a significant zoonotic disease in China, requiring the strengthening of food safety for control of this food-borne disease.
Toxicity of Barringtonia racemosa (L.) Kernel Extract on Pomacea canaliculata (Ampullariidae) by Musri Musman, Marine Science Department of Marine and Fishery Coordinatorate, Syiah Kuala University, Darussalam, Banda Aceh, Indonesia, Tropical Life Sciences Research, 21(2), 33–43, 2010
Abstract:A number of tropical plant species have been recognised as molluscicidal plants, and Barringtonia racemosa(L.) is one of these. The toxicity effects of B. racemosaseed kernel extracts to Pomacea canaliculatawere evaluated. The results of Trimmed Spearman-Karber Programme Version 1.5 calculations of LC50 (lower-upper limits) values, in ppm/48 h, were 70.71 (41.33-120.97), 94.39 (62.48-142.59), 186.84 (129.21-270.17), and 672.72 (366.57-1234.53) for the extracts withdrawn using dichloromethane, methanol, ethyl acetate, and heptane solvents, respectively at 95% C.I. It is assumed that the observed biological effects of the extracts may be due to the saponins and flavonoids present in the seed. The dichloromethanic and methanolic extracts contain saponin and flavonoid substances. Therefore, they have shown more potent molluscicidal activity towards the tested organism compared to the remaining extracts. This observed biological activity suggests a promising role for B. racemosain the control of P. canaliculata.
[Wikipedia: Barringtonia racemosa is a tree in the family Lecythidaceae. Commonly known as the Powder-puff Tree. Found in coastal swamp forests and on the edges of estuaries in Mozambique and KwaZulu-Natal, South Africa.]
Winning the biodiversity arms race among freshwater gastropods: competition and coexistence through shell variability and predator avoidance by Alan P. Covich, Institute of Ecology, Odum School of Ecology, University of Georgia, Athens, GA 30602-2202, USA,Hydrobiologia, Volume 653, Number 1 / October, 2010, Published online:15 July 2010
Abstract.Explanations for the coexistence of many closely related species in inland waters continue to be generated more than 50 years after Hutchinson’s question: why are there so many kinds of animals? This review focuses on the hypothesis that high species diversity of freshwater gastropods results, in part, from predators maintaining biodiversity across a range of deep- and shallow-water habitats. Invertebrate predators, such as aquatic insects, and leeches consume soft tissue of pulmonate snails by penetrating shells of various shapes and sizes. Crayfish and large prawns chip around the shell aperture to enter thick shells and crush small shells with their mandibles. Crabs use their strong chelae to crush thin and thick shells. Fishes with pharyngeal teeth are major shell-breaking predators that combine with other vertebrate predators such as turtles and wading birds to increase the diversity of gastropod communities by regulating the abundance of dominant species. Although the generalized diets of most freshwater predators preclude tight co-evolutionary patterns of responses, there are combinations of predators that modify gastropod behavior and shell morphology in aquatic assemblages of different ages and depths. This combination of invertebrate and vertebrate predatory impacts led to competitive advantages among individual gastropods with different adaptations: (1) less vulnerable shell morphologies and sizes; (2) predator-avoidance behaviors; or (3) rapid and widespread dispersal with variable life histories. Some individuals develop thicker and/or narrow-opening shells or shells with spines and ridges. Other thin-shelled species crawl out of the water or burrow to lower their risk to shell-breaking or shell-entering predators. Some alter their age at first reproduction and grow rapidly into a size refuge. Fluctuations in water levels and introductions of non-native species can change competitive dominance relationships among gastropods and result in major losses of native species. Many different gastropod predators control species that are human disease vectors. Most snails and their predators provide other ecosystem services such as nutrient cycling and transfer of energy to higher trophic levels. Their persistence and diversity of native species require adaptive management and coordinated study.
First evidence of “paralytic shellfish toxins” and cylindrospermopsin in a Mexican freshwater system, Lago Catemaco, and apparent bioaccumulation of the toxins in “tegogolo” snails (Pomacea patula catemacensis) byJohn P. Berrya, , and Owen Lindb, a Department of Chemistry and Biochemistry, Florida International University, North Miami, FL 33181, USAb Department of Biology, Baylor University, Waco, TX, Toxicon, Volume 55, Issue 5, May 2010
Abstract. Exposure to cyanobacterial toxins in freshwater systems, including both direct (e.g., drinking water) and indirect (e.g., bioaccumulation in food webs) routes, is emerging as a potentially significant threat to human health. We investigated cyanobacterial toxins, specifically cylindrospermopsin (CYN), the microcystins (MCYST) and the “paralytic shellfish toxins” (PST), in Lago Catemaco (Veracruz, Mexico). Lago Catemaco is a tropical lake dominated by Cylindrospermopsis, specifically identified as Cylindrospermopsis catemaco and Cylindrospermopsis philippinensis, and characterized by an abundant, endemic species of snail (Pomacea patula catemacensis), known as “tegogolos,” that is both consumed locally and commercially important. Samples of water, including dissolved and particulate fractions, as well as extracts of tegogolos, were screened using highly specific and sensitive ELISA. ELISA identified CYN and PST at low concentrations in only one sample of seston; however, both toxins were detected at appreciable quantities in tegogolos. Calculated bioaccumulation factors (BAF) support bioaccumulation of both toxins in tegogolos. The presence of CYN in the phytoplankton was further confirmed by HPLC-UV and LC-MS, following concentration and extraction of algal cells, but the toxin could not be confirmed by these methods in tegogolos. These data represent the first published evidence for CYN and the PST in Lago Catemaco and, indeed, for any freshwater system in Mexico. Identification of the apparent bioaccumulation of these toxins in tegogolos may suggest the need to further our understanding of the transfer of cyanobacterial toxins in freshwater food webs as it relates to human health.
Environmental significance of freshwater mollusks in the Southern Pampas, Argentina: to what detail can local environments be inferred from mollusk composition? by Tietze, E; De Francesco, CG, J. Saros, & L. Naselli Flores, a cura di). Dordrecht : Springer (2010)
Abstract. The aim of the present contribution is to assess whether the abundance of mollusk species in the Southern Pampas (Argentina), an environmentally homogeneous region, reflect the local conditions of water bodies. In order to test this hypothesis, a comprehensive study was conducted in 30 sites regularly distributed across the region. At each site, the abundance of mollusk species was determined, and a series of physico-chemical measurements taken. Principal Component Analysis (PCA) and Cluster Analysis (CA) were used for the ordination of sampling sites based on the measured environmental variables. In addition, Canonical Correspondence Analysis (CCA) was conducted to explore the relationships between environmental variables and mollusk abundances. Mollusk species were represented by the gastropods Biomphalaria peregrina, Chilina parchappii, Heleobia parchappii, Physa acuta, Pomacea canaliculata, Stenophysa marmorata, Uncancylus concentricus and the bivalve Musculium argentinum. Although aquatic vegetation cover, conductivity, and substrate were among the main parameters influencing mollusk distribution, their effect was insufficient to explain the spatial distribution pattern of the species in a regional scale. It is because the Southern Pampas is a very homogeneous area, and the ranges of these environmental conditions are within the range of ecological tolerance of most of the species represented. Yet, some species resulted good indicators of environmental conditions at local (microhabitat) scale, i.e., particular microhabitats that occur in different water bodies as well. In fact, even distributed in many different water bodies along the Southern Pampas C. parchappii is always linked to lotic environments, and U. concentricus is exclusively restricted to hard substrata. On the other hand, H. parchappii is the only species represented in mesohaline waters and P. acuta appeared to be a good indicator of pollution in the area.
Improved molecular detection of Angiostrongylus cantonensis in mollusks and other environmental samples with a species-specific ITS1-based TaqMan assay byYvonne Qvarnstrom, Ana Cristina Aramburu da Silva, John L Teem, Robert Hollingsworth, Henry Bishop, Carlos Graeff-Teixeira, and Alexandre J da Silva, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Public Health Service, U. S. Department of Health and Human Services, Atlanta, GA, USA 30333; Molecular Parasitology Laboratory, Institute of Biomedical Research of PUCRS, Laboratório de Biologia Parasitária, Faculdade de Biociências da PUCRS, Porto Alegre, Brazil; Division of Aquaculture, Florida Department of Agriculture and Consumer Services, Florida, USA; US Pacific Basin Agricultural Research Center, US Department of Agriculture, Hilo, Hawaii, USA
Abstract. Angiostrongylus cantonensis is the most common cause of humaneosinophilic meningitis. Humans become infected by ingestingfood items contaminated with 3rd stage larvae that develop inmollusks. We report the development of a real-time PCR assayfor the species-specific identification of A. cantonensis inmollusk tissue.
Palatability of macrophytes to the invasive freshwater snail Pomacea canaliculata: differential effects of multiple plant traits by PAK KI WONG, YAN LIANG, NGA YING LIU and JIAN-WEN QIU, Department of Biology, Hong Kong Baptist University, Hong Kong, China, Freshwater Biology, Blackwell Publishing Ltd, June 2010
1. By selective grazing, invasive grazers can alter macrophyte-herbivore relationships in shallow freshwater bodies. Evaluating the palatability of macrophytes and understanding the determinants of plant palatability can help predict grazing impact. In no-choice feeding assays, we tested the palatability of 21 species of freshwater macrophytes to the invasive freshwater apple snail Pomacea canaliculata.
2. Daily feeding rate varied greatly with plant species, ranging from 1.1 to 22% of snail body mass. We assessed six plant properties and examined their correlation with feeding rate. Total nitrogen content was positively related, and C:N ratio and dry matter content (DMC) negatively related, to snail feeding rate. There was no significant correlation between snail feeding rate and plant phenolic content, but the feeding rate on Myriophyllum aquaticum (the plant with the highest phenolic content) was very low.
3. We repeated the feeding assays for 15 species that were not palatable as fresh leaves with reconstituted plant tissues formed by mixing ground up dried leaves with agar. The feeding rate still differed greatly among macrophyte species. Phragmites australis and Vallisneria natans (two species with the highest DMC) were eaten much more as reconstituted plant than as fresh leaves, indicating that structure (i.e. DMC) may be important in their defense against snail herbivory. For two plants (M. aquaticum and Alternanthera philoxeroides) that had moderate amounts of nitrogen/phosphorus but were consumed very little as fresh and reconstituted tissues, we incorporated their extracts into a palatable agar-based food. The extracts from both species greatly reduced snail feeding rate, indicating the presence of chemical defenses in these two species.
4. These results indicated that feeding was affected by several plant traits. The snail favored plants with a high nitrogen content and avoided plants with a high DMC. Only a few plants possessed chemical feeding deterrents that were effective against this snail. Given the invasive spread of P. canaliculata in Asia, ecologists and managers should consider plant palatability when selecting plants for use in wetland restoration and when predicting the impact of further invasion by this species.
Arsenic in Cambodian Reservoirs and Potential for Treatment byMURPHY Tom1, SAMPSON Mickey2, IRVINE Kim3, DROPPO Ian4 and LE Chris5, 1Box 1537, Phnom Penh, Cambodia, 2Resource Development International (RDI), Royal Brick Road, Kien Svay, Kandal, P.O. Box 494, Phnom Penh, Cambodia, 3Buffalo State, State University of New York, 1300 Elmwood Avenue, Buffalo, New York, U.S.A., 14222, 4Environment Canada, 867 Lakeshore Road, Burlington, Ontario, Canada, L7R 4A6, 5Faculty of Medicine and Dentistry, 10-102 Clinical Sciences Building, University of Alberta, Edmonton, Alberta, Canada, T6G 2G3, International Lake Environment Committee Foundation (ILEC), May 2010
Exerpt. Although much of the food collected from the wetlands would not satisfy international guidelines, wetland foods are an important source of protein, iron and other nutrients to poor Cambodians. Apple snails (Pomacea canaliculata) were chosen as the main indicator organism of arsenic bioaccumulation because they are frequently eaten, especially by the poor, they are commonly found in wetlands and rice paddies and they are easy to collect. Apple snails were held in clean water for 24 hours to allow them to purge their guts. Because of the complications associated with fish collection (many species, varying size, migration etc), we chose to do more speciation analysis on snails. It was relatively easy to collect several snails from each site with relatively constant size to form duplicate/aggregate samples. They were freeze dried prior to being ground and blended with a food processor. For total arsenic analysis, 0.7 g of snails or clams was processed. For speciation of arsenic, 0.95 g of snails or clams was processed. The average total arsenic content in snails and clams in the natural wetlands was 7740±2170 μg/kg, n=17, of which 5.4%±6.3% was arsenate. The clams and snails with the highest bioaccumulation were found in sites with the most arsenic in the water and sediment. The dietary intake of snail as a percentage of the RfD for arsenic was 4%, but 4400% for drinking water.
A pooling strategy of a PCR-based assay to detect Angiostrongylus cantonensis in snail intermediate host, Pomacea canaliculata by Fu-Rong Wei, Shan Lv, He-Xiang Liu, Ling Hu and Yi Zhang, Department of Vector Control, National Institute of Parasitic Disease, Chinese Center for Disease Control and Prevention, Key Laboratory of Parasite and Vector Biology of the Ministry of Health, Shanghai, 200025, China,Higher Education Press, co-published with Springer-Verlag, May 2010
Abstract. Pooling field specimens could reduce the number of assay and thus increase the efficiency in detecting and screening pathogen infections by polymerase chain reaction (PCR)-based assay. We investigated a pooling strategy in diagnosis of Angiostrongylus cantonensis in Pomacea canaliculata. Two settings of specimens were prepared, divided into portions and detected by multiplex PCR. Specimens A was 0.4490 g positive lung tissue of 28 larval nodes from four snails mixed with 1.310 g negative lung tissue from six snails and divided into 32 portions. Specimens B was 0.5448 g positive lung tissue with 26 larval nodes from two snails mixed with 1.092 g negative lung tissue from seven snails and divided into 48 portions. Repeated sampling was performed and sample size-accumulated positive rate curves were drawn. According to the sample size-accumulated positive rate curves, the appropriate sample size of the two specimens were 18 and 15, respectively, which is 0.36–0.58 to the total sample size. These test characteristics and the relevant factors to the sample size would need to be determined in much larger studies and more appropriately in field populations. The result indicates that the number of larval node is not the most important, nor the only factor to the sample size. It also implies the feasibility to detect A. cantonensis in P. canaliculata by pooling strategies.
Aquatic molluscs as auxiliary hosts for terrestrial nematode parasites: implications for pathogen transmission in a changing climate by N. J. MORLEY, School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK, Parasitology Cambridge University Press, April 2010
Abstract. Nematodes are common parasites of molluscs but are often overlooked. Both metastrongyloid and rhabditoid species dominate the fauna within land snail and slug populations. Nevertheless, a key characteristic of many laboratory studies is the ability of these terrestrial nematodes to utilize aquatic molluscs as auxiliary hosts. The significance of this to the ecology of the parasite has never been evaluated. There is increasing concern as to the impact of climate change on the epidemiology of many parasitic diseases. In particular, it has been suggested that host switching may increase under the pressure of extreme climatic conditions. It is therefore timely to assess the role that aquatic molluscs may play in transmitting terrestrial nematodes, which include species of medical and veterinary importance such as Angiostrongylus cantonensis, A. vasorum, and Muellerius capillaris. The present review assesses the mechanisms of terrestrial nematode transmission through aquatic molluscs focusing on metastrongyloid and rhabditoid species, the importance of variable susceptibility of molluscan hosts, field studies on natural occurrence within aquatic habitats, and the impact of extreme climatic events (floods and droughts) that may increase in frequency under climate change.
Learned Predator Recognition in a Freshwater Snail, Pomacea canaliculatabyKahori Aizaki & Yoichi Yusa, Faculty of Science, Nara Women’s University, Kitauoya-nishi, Nara 630-8506, Japan, Malacologia 52(1):21-29. 2010
Abstract. The involvement of associative learning in predator recognition has not been clear in aquatic invertebrates, including molluscs, due to confounding effects of sensitization. The freshwater apple snail, Pomacea canaliculata, displays an alarm response (crawling above the waterline) when exposed to crushed conspecifics or some predators. We conducted two series of experiments to investigate whether the apple snail learns to avoid predators. In the first experiment, hatchlings were conditioned simultaneously to crushed conspecifics and either a live carp, Cyprinus carpio, or a turtle, Chinemys reevesii, and subsequently exposed to the same predator without crushed conspecifics. Irrespective of the predator species used, the alarm response was significantly higher in conditioned snails than in unconditioned snails. Thus, the snail is able to avoid predators by learning, in a broad sense. In the second experiment, designed to distinguish associative learning from sensitization, we conditioned hatchlings to crushed conspecifics and either a carp or a turtle. The hatchlings were subsequently exposed to one or other of the predators. Hatchlings that were conditioned to a predator displayed significantly higher alarm response when later exposed to the same predator than another predator, suggesting that the snail can recognize predators by associative learning.
Differences in population dynamics and potential impacts of a freshwater invader driven by temporal habitat stability by Lyubov E. Burlakova1, 2 , Dianna K. Padilla3, Alexander Y. Karatayev1, David N. Hollas4, 5, Leah D. Cartwright4, 6 and Kevin D. Nichol4, 7 1. Great Lakes Center, Buffalo State College, 1300 Elmwood Avenue, Buffalo, NY, 2. Buffalo State College, Office of Sponsored Programs, The Research Foundation of The State University of New York, 1300 Elmwood Avenue, Bishop Hall B17, Buffalo, NY, USA, 3. Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 4. Division of Environmental Science, Stephen F. Austin State University, P. O. Box 13073, SFA Station, Nacogdoches, 5. Smith International, Inc., 16740 Hardy Street (77032), P. O. Box 60068, Houston, TX, 6. URS Corporation, 9801 Westheimer, Suite 500, Houston, TX, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD, in Biological Invasions Volume 12, Number 4 / April, 2010
Abstract. Population dynamics and population regulation of invasive species is critical for predicting their effects on native ecosystems as well as for control strategies. Many species of gastropod in the genus Pomacea are successful aquatic invaders that have caused economic and ecological impacts in Southeastern Asia where their large fecundity and broad reproductive window helps them to colonize and take advantages of ephemeral agricultural habitats. We followed the population dynamics of P. insularum in permanent, stable freshwater systems (ponds and streams), and in ephemeral agricultural habitats in the upper Texas Gulf Coast region, USA. We found that although P. insularum has a large reproductive potential, its density, biomass and size structure in stable permanent systems did not change significantly from March to November, and densities averaged <2 m−2. This same species, however, displayed very different population dynamics in ephemeral agricultural environments. We found high densities (>130 m−2), and no stable size structure through time. Differences in the stability and persistence of these two types of environments appear to drive these patterns. Stability and persistence of habitats can result in different predator communities and the risk of predation for snails. We suggest that such factors may cause the differences in population dynamics and structure observed. The ability of snails to escape population control and explode in ephemeral habitats could drive the types of impacts seen on agricultural crops.
Pink eggs and snails: field oviposition patterns of an invasive snail, Pomacea insularum, indicate a preference for an invasive macrophyte by Romi L. Burks1, Colin H. Kyle2, and Matthew K. Trawick1, 1 Department of Biology, Southwestern University, Georgetown, TX 78626, 2 Ecology and Evolution, University of Chicago, 1101 E 57th Street, Chicago, IL 60637, USA USA, Hydrobiologia (2010) 646:243–251, March 2010
Abstract. Oviposition of non-calcareous or thinly shelled eggs represents an important life stage of many insects, amphibians, and several gastropods. A recently identified invasive species of apple snail, Pomacea insularum, exhibits alarming invasive characteristics of high reproductive rates and generalist consumption patterns. This snail takes the opposite approach to egg laying compared to most aquatic insects as adult snails crawl out of the water to place clutches on emergent, or terrestrial, substrates. As fecundity best indicates invasive potential for mollusks, control or management efforts need to understand reproductive behavior in P. insularum to predict, and hopefully impede, its spread throughout the Gulf Coast of the United States. Specific characteristics of wetlands and shallow lakes may facilitate the invasion process of P. insularum by providing females with conditions that permit successful oviposition. In order to investigate this possibility, we studied P. insularum oviposition behavior in an invasive population at two times during the reproductive season in Texas, USA. Based on a subsequent survey (August 2009), plants comprised 78% of the available habitat. Wild taro (Colocasia esculenta) and alligator weed (Alternanthera philoxeroides) represented 48 and 43% of that proportion, respectively. During 2008–2009, no new concrete or metal structures appeared in our sampling reach and consistent amounts of plant stands and woody debris remained dominant. Given this distribution, P. insularum laid disproportionately more clutches on wild taro compared to its availability and less on alligator weed and bulrush (Schoenoplectus californicus) than expected. Owing to limited metal and concrete substrates, we found a higher proportion of clutches on these artificial substrates than expected in both May and August 2008. However, artificial substrates comprised less than 2% of available substrates in the bayou. Our results suggest that wetlands and shallow lakes surrounded by large emergent macrophytes, particularly wild taro, likely provide ideal oviposition sites for P. insularum, promote egg supply, and possibly facilitate invasion into new aquatic ecosystems.
Published online: 1 March 2010 by Springer Science+Business Media B.V. 2010
Responses of freshwater molluscs to environmental factors in Southern Brazil wetlands by Maltchik, L.I,*; Stenert, C.I; Kotzian, CB.II; Pereira; D.III ILaboratório de Ecologia e Conservação de Ecossistemas Aquáticos, Universidade do Vale do Rio dos Sinos – UNISINOS, Av. Unisinos, 950, CEP 93022-000, São Leopoldo, RS, Brazil IIDepartamento de Biologia, Universidade Federal de Santa Maria – UFSM, CEP 97105-900, Santa Maria, RS, Brazil IIILaboratório de Malacologia, Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul – PUCRS, Av. Ipiranga, 6681, CEP 90619-900, Porto Alegre, RS, Brazil Brazilian Journal of Biology, ISSN 1519-6984 (March 2010)
Abstract. Freshwater molluscs play an important role in aquatic ecosystems, providing food for many fish species and vertebrates. Investigations on factors that determine mollusc species richness and distribution in wetland systems are scarce in the Neotropical region. The main goal of this study was to determine how much variation in mollusc richness and composition is explained by area, hydroperiod, altitude, water conductivity, and dominant aquatic vegetation. This survey was performed in an extensive area of a Neotropical region (~280,000 km2 in southern Brazil), with a large number of wetland systems (111) and covering a wide gradient of altitude and wetland surface area. The mollusc richness was positively associated with wetland area and negatively associated with altitude. The richness and composition of the freshwater molluscs were similar between permanent and intermittent wetlands and it did not differ significantly between aquatic bed and emergent wetlands. The first three axes of CCA explained 16.2% of the total variation in the composition of the freshwater mollusc observed. The variation in the composition had a correlation with wetland area, altitude and water conductivity. Our results showed that the wetlands are important habitats for molluscs in southern Brazil, and that the richness and the composition of molluscs were associated with area, altitude, water conductivity and dominant vegetation.
Exotic vertebrate and invertebrate herbivores differ in their impacts on native and exotic plants: a meta-analysis by Ayub M. O. Oduor1, José M. Gómez1 and Sharon Y. Strauss2 1. Dpto de Ecología, Universidad de Granada, Spain, 2. Section of Evolution and Ecology, University of California Davis, Davis, CA, USA Biological Invasions, Volume 12, Number 2, February, 2010
Abstract. Herbivores modify various ecological processes including interactions between native and exotic plants that may affect invasion success by the exotic plants. It is unknown whether different types of exotic herbivores have similar effects on native and exotic plants. Using two distinct data sets, we ran meta-analyses to compare exotic vertebrate and invertebrate herbivore preferences for, and effects on performance and population sizes of native and exotic plants. We found that exotic vertebrate herbivores have positive effects on exotic plant performance and population sizes, and no significant effects on native plants. Exotic invertebrates have significant negative effects on performance and population sizes of both exotic and native plants. Vertebrates prefer to feed on native plants relative to exotic plants, while invertebrates prefer the exotic plants to native plants. Thus the exotic vertebrate herbivores may aid invasiveness of exotic plants, in accordance with the invasional meltdown hypothesis, while exotic invertebrate herbivores probably have no net effect on invasion process of the exotic plants. Invertebrate herbivore preferences for exotic plants support the biotic resistance hypothesis, as the native plants probably resist the invertebrate herbivory. We also tested an evolutionary logic that posits that herbivores with similar evolutionary history as plants will affect the plants less negatively than plants with which they have not co-evolved. Our results indicate that there is no consistent pattern in effects of exotic vertebrate and invertebrate herbivores on exotic plants with or without which they have co-evolved.
FEEDING RATES OF AN INTRODUCED FRESHWATER GASTROPOD POMACEA INSULARUM ON NATIVE AND NONINDIGENOUS AQUATIC PLANTS IN FLORIDA by Patrick Baker, Frank Zimmanck and Shirley M. Baker, Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation, University of Florida, Journal Molluscan Studies Advance Access published online on January 19, 2010
Abstract. Pomacea insularum (Gastropoda: Ampullariidae) is a common, nonindigenousspecies in many parts of the world and an important consumerof aquatic macrophytes. We conducted laboratory trials to quantifythe rates of consumption of native and nonindigenous aquaticplants in Florida, where this snail has been introduced. Twenty-twofreshwater plant and alga species were presented to naïveP. insularum in laboratory trials, using single-snail replicatesand simultaneous (no-snail) controls. Pomacea insularum damaged>50% of the replicate plants of 16 species; for 14 of thesewe calculated ash-free dry weight-specific feeding rates ofP. insularum. The most heavily consumed plants were two nativespecies: Limnobium spongia (0.744 g/g/d) and Chara sp. (0.478g/g/d). Nonindigenous Panicum repens (0.306 g/g/d), Hydrillaverticillata (0.292 g/g/d) and Ceratophyllum demersum (0.254g/g/d); and native Sagittaria latifolia (0.257 g/g/d), Najasguadalupensis (0.225 g/g/d) and Vallisneria americana (0.207g/g/d) were also heavily consumed. Nonindigenous Eichhorniacrassipes was consumed at a lower rate (0.053 g/g/d) while nonindigenousColocasia esculenta and Pistia stratiotes were not consumedat detectable levels. Our results suggest that P. insularumcannot be relied upon as a biological control agent for nonindigenousplants and may heavily impact native macrophytes.
A high incidence of imposex in Pomacea apple snails in Taiwan: a decade after triphenyltin was banned by Jing-Ying Wu, Pei-Jie Meng, Ming-Yie Liu, Yuh-Wen Chiu, and Li-Lian Liu, Zoological Studies 49(1): 85-93 (2010)
Abstract. The South American apple snails Pomacea canaliculata and P. scalaris were intentionally introduced into Taiwan in the 1980s. Subsequently, P. canaliculata has become a serious pest to aquatic crops, and triphenyltin (TPT) was the major control agent. We conducted a nationwide survey on the imposex status of P. canaliculata and P. scalaris to evaluate the effectiveness of the ban on TPT use in agriculture since 1999. Pomacea canaliculata was distributed island-wide, but P. scalaris was only distributed in southern Taiwan, sympatrically with P. canaliculata. The imposex condition was found in snails from all collecting sites of the 2 species. Based on vas deferens sequence (VDS) indices, P. scalaris and P. canaliculata have the same susceptibility. Additionally, imposex-affected individuals of P. canaliculata were found in all types of freshwater habitats, i.e., crop drainage, reservoirs, and wastewater drainage, with respective VDS indices ranging 1.02-1.40, 0.75-2.00, and 1.00-1.88. Based on these survey results, the illegal use of TPT in agriculture has likely continued, and extra control actions are urgently needed.
Dependence on aerial respiration and its influence on microdistribution in the invasive freshwater snail Pomacea canaliculata by María E. Seuffert and Pablo R. Martín, Biological Invasions, Volume 12, Number 6, 2009
Abstract. The invasive Neotropical snail Pomacea canaliculata is usually regarded as amphibious, although the relative significance of aerial and aquatic respiration is unknown. To investigate the degree of dependence on aerial respiration and its influences on microdistribution, experiments were performed in the laboratory and under seminatural and natural conditions. Restriction of aerial respiration negatively affected survivorship, activity and feeding, its effects worsening with temperature and water fouling; females were more seriously affected than males although the effect depended on reproductive effort. Snails were unevenly distributed relative to the access to air, both in a stream and in an outdoor tank, being concentrated less than 2–4 m from the nearest emergent substratum. Accessibility to air would be an important trait of waterbodies prone to invasions of P. canaliculata, especially in tropical areas. The effectiveness of some control measures could be increased by focusing on areas where snails are concentrated due to their dependence on air.
Evolution, molecular systematics and invasion biology of Ampullariidae by Hayes, KennethA., Ph.D., Dissertation, University of Hawai’i at Manoa, 213 pages, 2009
Abstract. Apple snails (Ampullariidae) are freshwater, operculate snails globally distributed in humid tropical and subtropical habitats. Nine genera are recognized: Afropomus , Saulea and Lanistes are African; Pila is African and Asian; Asolene , Felipponea , Marisa and Pomella are South American; Pomacea ranges from Argentina to the southeastern USA. Ampullariid taxonomy and evolutionary relationships have historically been poorly understood, especially regarding Pomacea , which has implications for research on many aspects of ampullariid evolutionary biology. In this dissertation I present the most comprehensive assessment of ampullariid phylogenetic systematics to date and explore some central themes in evolutionary biology that are pertinent to apple snails and their evolution in the Neotropics. In reconstructing the phylogenetic relationships of the ampullariids I used two mitochondrial and three nuclear genes. Analyses of these genes independently and in combination support the reciprocal monophyly of the New and Old World taxa and confirm the need for a taxonomic revision of the New World genera. The phylogeny also reveals a trend of increasingly amphibious habits among some of the more derived ampullariids. Such changes in habits appear to have evolved in parallel with increases in siphon length and expansion of the lung, efficacy of atmospheric oxygen uptake, diversification and enlargement of the copulatory apparatus, desiccation resistance, oviposition behavior and egg morphology. All these changes, in concert with the changing freshwater systems of the Neotropics during the last 90 myr, have probably played a significant role in the evolution of ampullariids. Understanding such processes combined with the well resolved phylogeny have allowed me to better characterize apple snail invasiveness and accurately identify those species introduced outside their native ranges. Finally, since the Ampullariidae are probably the sister group to all Caenogastropoda, this phylogeny establishes the basis for future studies that will provide insights into gastropod evolution in general.
POPULATION DYNAMICS OF AN ESTABLISHED REPRODUCING POPULATION OF THE INVASIVE APPLE SNAIL (POMACEA INSULARUM) IN SUBURBAN SOUTHEAST HOUSTON, TEXAS by Colin H. Kyle, Matthew K. Trawick, James P. McDonough and Romi L. Burks, Department of Biology, 1001 East University Avenue, Southwestern University, Georgetown, Texas 78626,TEXAS J. SCI. 61(4), NOVEMBER, 2009
Conclusion. Invading habitats worldwide, apple snails of the genus Pomacea now represent an increasing environmental problem in the U.S. Multiple introductions (Rawlings et al. 2007) of numerous species from multiple origins (Hayes et al. 2008) complicate this problem. For the first time, this study documents the presence of the growing size distributions of populations of invasive P. insularum in southeast Texas. However, scientists still know little about the abilityof this species to damage local ecosystems. Due to their recent presence, only limited estimates on the reproductive ability of P.insularum exist (Barnes et al. 2008). However, the potential population growth made possible by females routinely laying large egg clutches (each containing approximately 2000 eggs; Barnes et al.2008) warrants serious concern. Without further investigation of the population size structure, invasive ecologists cannot accurately predict the effects of P. insularum on aquatic Texas ecosystems. Ecologists must conduct future research, specifically density estimations andconsumption rates, to understand fully the overall effect P. insularum will have in southeast Texas and possibly along the entire Gulf coast.
Use of a saponin based molluscicide to control Pomacea canaliculata snails in Southern Brazil by San Martíns R, Gelmi C, de Oliveira JV, Galo JL, Pranto H., Pontificia Universidad Católica de Chile, Dept of Chemical and Bioprocess Engineering, Santiago, Chile, Nat Prod Commun. 4(10):1327-30, October 2009
Abstract. Pomacea canaliculata snails pose a severe problem to direct seeded rice cultivated in Southern Brazil. Control of this snail is nowadays performed with toxic chemicals such as copper sulfate and fungicides such as fentin. A novel natural molluscicide based on alkali modified quinoa (Chenopodium quinoa) saponins was tested under laboratory conditions. Snails were collected in rice fields close to Porto Alegre (State of Rio Grande do Sul) and in Brusque (State of Santa Catarina, 400 km north of Porto Alegre). In Santa Catarina the product was very effective, while in Porto Alegre it had no effect. This unexpected behavior was probably due to the respiratory habits of the snails under different contents of dissolved oxygen in the water. Near Porto Alegre the water used in rice fields is heavily polluted, with dissolved oxygen levels of 1-2 ppm, and the snails rely primarily on their siphon and lungs to breathe. Since saponin control is probably due to an interaction between saponins with the sterols present in the cell walls in the gills, no control was observed. By contrast, in Santa Catarina the dissolved oxygen level of the water is 5-6 ppm, and the snails remain mostly underwater, breathing with their gills. In this case the snails died within 24 h at a dose of 20 and 30 ppm of product. To test this observation, snails grown in polluted waters were forced to remain underwater in saponin solutions and water (control) preventing the use of their siphon to breathe. The snails exposed to saponin solutions died, while the control snails survived, indicating that they were still able to use their gills to breathe. These results indicate that the use of the saponin product is limited to rice fields not irrigated with heavily polluted waters.
Dependence on aerial respiration and its influence on microdistribution in the invasive freshwater snail Pomacea canaliculata (Caenogastropoda, Ampullariidae) by María E. Seuffert and Pablo R. Martín, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina, Biol Invasions, September 2009
Abstract. The invasive Neotropical snail Pomacea canaliculata is usually regarded as amphibious, although the relative significance of aerial and aquatic respiration is unknown. To investigate the degree of dependence on aerial respiration and its influences on microdistribution, experiments were performed in the laboratory and under seminatural and natural conditions. Restriction of aerial respiration negatively affected survivorship, activity and feeding, its effects worsening with temperature and water fouling; females were more seriously affected than males although the effect depended on reproductive effort. Snails were unevenly distributed relative to the access to air, both in a stream and in an outdoor tank, being concentrated less than 2–4 m from the nearest emergent substratum. Accessibility to air would be an important trait of waterbodies prone to invasions of P. canaliculata, especially in tropical areas. The effectiveness of some control measures could be increased by focusing on areas where snails are concentrated due to their dependence on air. http://www.springerlink.com/content/4074w2j045u22w1n/
Secondary production and diet of an invasive snail in freshwater wetlands: implications for resource utilization and competition byKing Lun Kwong1, David Dudgeon2, Pak Ki Wong1 and Jian-Wen Qiu1 Department of Biology, Hong Kong Baptist University ,2 Division of Ecology and Biodiversity, School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China, Biological Invasions (August 2009)
Abstract. Invasive species can monopolize resources and thus dominate ecosystem production. In this study we estimated secondary production and diet of four populations of Pomacea canaliculata, a freshwater invasive snail, in wetlands (abandoned paddy, oxbow pond, drainage channel, and river meander) in monsoonal Hong Kong (lat. 22°N). Apple snail secondary production (ash-free dry mass [AFDM]) ranged from 165.9 to 233.3 g m−2 year−1, and varied between seasons. Production was lower during the cool dry northeast monsoon, when water temperatures might have limited growth, but fast growth and recruitment of multiple cohorts were possible throughout much (7–10 months) of the year and especially during the warm, wet southwest monsoon. The diet, as revealed by stomach-content analysis, consisted mainly of detritus and macrophytes, and was broadly consistent among habitats despite considerable variation in the composition and cover of aquatic plants. Apple snail annual production was >10 times greater than production estimates for other benthic macroinvertebrates in Hong Kong (range 0.004–15 g AFDM m−2 year−1, n = 29). Furthermore, annual production estimates for three apple snail populations (i.e. >230 g AFDM m−2 year−1) were greater than published estimates for any other freshwater snails (range 0.002–194 g AFDM m−2 year−1, n = 33), regardless of climatic regime or habitat type. High production by P. canaliculata in Hong Kong was attributable to the topical climate (annual mean ~24°C), permitting rapid growth and repeated reproduction, together with dietary flexibility including an ability to consume a range of macrophytes. If invasive P. canaliculata can monopolize food resources, its high productivity indicates potential for competition with other macroinvertebrate primary consumers. Manipulative experiments will be needed to quantify these impacts on biodiversity and ecosystem function in wetlands, combined with management strategies to prevent further range extension by P. canaliculata.
The effectiveness of animal attractants to the apple snail Pomacea canaliculata by Wei-jhen Sun, Master’s Thesis, Department of Life Sciences, National Taiwan University, August 4, 2009.
Abstract. The apple snail, Pomacea canaliculata has made a tremendous threat to aquatic agricultural crops for many years. But safe and effective methods to eliminate them are still not available. Traditionally, pesticides are the most common way to kill apple snails. However, the occurrence of drug resistance and drug residual causes even more serious problems. The present study was conducted to evaluate the effectiveness of attractants to apple snails in the fields. The experiments included the effectiveness of different attractants and trap designs under different environmental conditions. It was found that attractants of banana pulp, chicken blood and condensed fish soluble were effective with at least 12-hour trapping time. The sizes of attracted snails were similar to the ambient snails. Snails (Pomacea scalaris, Sinotaia quadrata, Planorbioidae spp.), insects (Sphaerodema rustica, water scorpion), tadpoles and fishes (Poecilia reticulate, Trichogaster trichopterus) were also found in the traps. Besides, two-opening traps with funnel entrance were more effective than the traps without funnel entrance. In general, in still water with ambient density of apple snails range from 6.2± 6.1 to 50.3±14.2 individual/m2,the relationship between attracted snails and ambient snail density was negative in chicken blood group (p < 0.001), positive in condensed fish soluble (p < 0.05) and no trend in banana group (p > 0.05). The results support the hypothesis that areas with abundant food usually have high snail density and those snails are less attracted by potential food items.
Molluscan models in evolutionary biology: Apple snails (Gastropoda: Ampullariidae) as a system for addressing fundamental questions by Kenneth A. Hayes1,2, Robert H. Cowie1, Aslak Jørgensen3, Roland Schultheiß4, Christian Albrecht4, and Silvana C. Thiengo5, 1 Center for Conservation Research and Training, Pacifi c Biosciences Research Center, University of Hawaii, 2 Department of Zoology, University of Hawaii 3 Mandahl-Barth Research Centre for Biodiversity and Health, DBL–Centre for Health Research and Development, Department of Disease Biology, The Faculty of Life Sciences, University of Copenhagen, 4 Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Germany 5 Departamento de Malacologia, Instituto Oswaldo Cruz, Brasil, Amer. Malac. Bull. 27: 47-58 (2009)
Abstract. Molluscs constitute the second largest phylum in terms of the number of described species and possess a wide array of characteristics and adaptations for living in marine, terrestrial, and freshwater habitats. They are morphologically diverse and appear in the fossil record as far back as the early Cambrian (~560 mybp). Despite their high diversity and long evolutionary history, molluscs are often underused as modelsfor the study of general aspects of evolutionary biology. Freshwater snails in the family Ampullariidae have a global tropical and subtropical distribution and high diversity with more than 150 species in nine currently recognized genera, making them an ideal group to address questions of historical biogeography and some of the underlying mechanisms of speciation. They exhibit a wide range of morphological, behavioral, and physiological adaptations that have probably played a role in the processes of diversifi cation. Here we review some of the salient aspects of ampullariid evolution and present some early results from ongoing research in order to illustrate the excellent opportunity that this group provides as a system for addressing numerous questions in evolutionary biology, particularly with regard to the generation of biodiversity and its distribution around the globe. Specifi cally, we suggest that ampullariids have great potential to inform (1) biogeography, both on a global scale and a smaller intra-continental scale, (2) speciation and the generation of biodiversity, through analysis of trophic relations and habitat partitioning, and addressing issues such as Rapoport’s Rule and the latitudinal biodiversity gradient, and (3) the evolution of physiological and behavioral adaptations. Also, a number of species in the family have become highly successful invasives, providing unintentional experiments that may offer insights into rapid evolutionary changes that often accompany introductions, as well as illuminating invasion biology in general.
Not a slow snail: Rapid rise of environmental awareness and ecological insights regarding invasive island applesnails (Pomacea insularum) by Romi Burks, Southwestern University and Jess Van Dyke, Florida Department of Environmental Protection (retired). The 94th ESA Annual Meeting (August 2 — 7, 2009)
Abstract. Exotic invaders routinely move faster than scientific publication processes. Lacking aerial dispersal stages, snails generally match descriptions of slow colonizers. However, reminiscent of the pace with which zebra mussels gained notoriety, a growing sense of urgency has emerged from management communities regarding established populations of exotic, invasive island apple snails (Pomacea insularum). Recently separated by mitochondrial markers as a related, yet distinct, species, P. insularum sits poised to follow along the invasive trajectory of its better known relative, the golden apple snail (P. canaliculata). Literature studies examining mechanisms that promote invasiveness suggest family history of invasion serves as a sufficient enough warning sign. Furthermore, a paucity of natural history information exists on this larger (max wet weight 166-g), more fecund (2000 eggs as average clutch size) aquatic plant consumer. Without insights into basic life history, actions within management agencies often stall. In just the past five years, multiple introductions gave rise to established reproductive populations across the entire Gulf Coast, from Texas to Florida and even northward to South Carolina. Using a combination of empirical results from multiple experiments and recently compiled insights from researchers studying invasive apple snails (encapsulated as a blog: http://snailbusters.wordpress.com/), we explore three questions. First, what patterns in life history emerge for P. insularum? Second, what natural history aspects appear missing? And third, how can dissemination of new findings shape future studies?
Synthesis of experiments and observations from Texas provide compelling (i.e. statistically significant) evidence that P. insularum preferentially chooses to deposit clutches on emergent plants. Snails favor plants with strong circular stems, particularly elephant ear (Colocasia esculenta). Unfortunately, easy to measure clutch characteristics (e.g. length, width, depth, volume) fail to predict hatching success. Female P. insularum snails tend to oviposit clutches substantially higher on plant stems than smaller female P. canaliculata. Permanent inundation of newly laid clutches completely prevents hatching, although the impact of water stress on clutch hatching efficiency varies with stress intensity and frequency. Complimentary research also notes differences depending in clutch developmental stage. Among managers and researchers, agreement clearly exists that the egg stage represents our best chance at slowing down the invasion. Relatively few studies focus on interactions (e.g. competition, predation) with native organisms. In conclusion, because clear time-pressure exists to protect native biodiversity, rise in popularity of non-traditional formats (e.g. blogs) to speed research along and increase networking has started providing insights in the case of invasive apple snails.
Preliminary investigations of Island Applesnails (Pomacea insularum) control methods applicable for natural areas in Louisiana by Jacoby Carter1, Jill Jenkins1, Christopher Wells1, Linda Broussard1, Sergio Merino2, Heather Olivier2, and Eric Theall2. (1) US Geological Survey, (2) IAP, The 94th ESA Annual Meeting (August 2 — 7, 2009)
Abstract. The Island Applesnail (Pomacea insularum) is a new invasive species in South Louisiana. First reported in 2005 in a canal south of New Orleans, Louisiana, there are now 3 know watersheds where they exist. Each site is very different. One is a system residential water retention ponds; another is a series of drainage canals; and the third is a swamp and associated river system. Each population seems to be a separate introduction based on location, habitat type and distance from other known populations. Applesnails have been documented to have devastating impacts on wetland agricultural crops such as rice and taro. They also have been shown to shift swamp ecosystems in Southeast Asia from macrophyte to algae based systems by overgrazing. Furthermore they are an intermediate host for the rat lungworm (Angiostrongylus cantonensis) a nematode that can infect and cause meningitis in humans. Most control efforts have focused on agricultural systems. We are exploring tools that are applicable in more naturally managed areas such as wildlife refuges, national parks, and private swamplands managed for crawfish productions. Techniques we have investigated include biological, chemical, and mechanical control.
Biological Control- we investigated the use of the native red swamp crayfish (Procambarus clarkii). They will eat small applesnails, but do not have a high preference for them. However, since they are native and are raised commercially, they have a high potential as an acceptable option in this region.
Chemical Control- we tested two classes of chemicals, saponins and niclosamides. Both were effective against applesnails and did not affect crawfish, an important consideration if we want to combine techniques. However, both are toxic to fish. Mechanical Control- through experimentation we showed that a common control method (knocking eggs into the water) was not completely effective and now recommend smashing the egg masses. An applesnail trap and bait are currently being tested.
Field inspection of the three known populations indicates that a healthy and diverse predator community may be important in keeping applesnails in check. These may include ducks that eat the eggs, otters that eat adult snails, and a variety of fish and reptiles that may take out various size classes of applesnails. A combination of control techniques and management of habitat to encourage natural predation may prove a successful strategy for south Louisiana.
Molluscicide from Tobacco Waste by Rochana Tangkoonboribun and Suriya Sassanarakkit, Agricultural Technology Department, Thailand Institute of Scientific and Technological Research Phathunthani, Thailand, Journal of Agricultural Science, Vol 1, No 1 (June 2009)
Abstract. Tobacco waste can be molluscicide for Golden Apple snail control in paddy field as trialed in 3 experiments e.g. laboratory, green house and field trial. In laboratory found LD50 of tobacco waste on golden apple snail, fish, frog andcrab were 5456.25, 687.5, 1562.5 and 5000 Kg/ha respectively. In greenhouse and field trial were found rate of tobacco waste at 1562.5 Kg/ha could kill golden apple snail 100% in two days. Tobacco waste affected to increased electrical conductivity, biological oxygen demand, chemical oxygen demand in water but decreased water pH and dissolved oxygen. Otherwise, tobacco waste can be supplied soil fertility with high organic matter, available phosphorus, exchangeable potassium, calcium and magnesium. Tobacco waste can be increased rice growth and yield without nicotine and acute toxicity inspected.
Physiological response to low temperature in the freshwater apple snail, Pomacea canaliculata by Keiichiro Matsukura1,*, Hisaaki Tsumuki2, Yohei Izumi2 and Takashi Wada1, Research Team for Insect and Nematode Management, National Agricultural Research Center for Kyushu Okinawa Region, Suya 2421, Koshi, Kumamoto 861-1192, Japan, 2 Research Institute for Bioresources, Okayama University, Kurashiki, Okayama 710-0046, Japan, Journal of Experimental Biology 212, 2558-2563 (May, 2009)
Abstract. Cold hardiness of the freshwater apple snail, Pomacea canaliculata,varies seasonally. We investigated lethal factors and physiologicalchanges arising from exposure of P. canaliculata to low temperatures.Snails did not survive freezing. The supercooling point of cold-acclimated(cold tolerant) snails (–6.6±0.8°C) did not differsignificantly from that of non-acclimated ones (–7.1±1.5°C)under laboratory conditions. Furthermore, snails died even undermore moderately low temperatures approaching 0°C. These resultsindicate that indirect chilling injury is a factor in the deathof P. canaliculata at low temperatures. Regardless of whetherthe snails were acclimated to low temperatures, all of the dead,and even some of the snails still alive at 0°C, had injuredmantles, indicating that the mantle may be the organ most susceptibleto the effects of low temperatures. The concentration of glucosein the posterior chamber of the kidney and concentration ofglycerol in the digestive gland were significantly higher in cold-acclimatedsnails than in non-acclimated ones, suggesting carbohydrate metabolicpathways are altered in snails during cold acclimation.
Exposure routes of copper: Short term effects on survival, weight, and uptake in Florida apple snails (Pomacea paludosa) by Tham C. Hoang and Gary M. Rand, Florida International University, Ecotoxicology and Risk Assessment Laboratory, Department of Environmental Studies, Southeast Environmental Research Center, North Miami, FL, J. Chemosphere, Copyright Elsevier, April 2009
Abstract. The uptake and effects (survival, weight) of copper (Cu) on Florida apple snails (Pomacea paludosa) via exposures to copper-enriched agricultural soil–water and water-only treatments were investigated. Soils were collected from citrus sites in south Florida and flooded with laboratory freshwater for 14 d. Neonate apple snails ( 96-h-old) were then exposed to either Cu from a soil-overlying water (i.e., flooded agricultural soils) treatment or overlying water-only (i.e., equilibrated overlying water produced from 14 d flooding of agriculture soils) treatment for 14 d under standard laboratory conditions. Survival, weight (dry, wet), and whole=2 0body Cu uptake were measured. Copper exposure via soil–water exposures resulted in higher mortality and whole body Cu uptake than water-only exposures, indicating Cu uptake from soils. However, snail wet and dry weights were higher in soil–water treatments than in water-only treatments. Micronutrients from soils may be consumed by snails increasing weights. Survival, apple snail dry weight, and whole body Cu concentrations were significantly correlated with soil and water Cu concentrations in soil–water treatments. Survival was significantly correlated with the concentration of in water-only treatments. This suggests that is toxic to apple snails. Whole body Cu concentrations were higher in surviving snails than dead snails, suggesting that apple snails have the ability to detoxify accumulated Cu (e.g., through metallothionein induction, granules).
Effects of macrophytes on feeding and life-history traits of the invasive apple snail Pomacea canaliculata by JIAN-WEN QIU and KING-LUN KWONG, Department of Biology, Hong Kong Baptist University, Hong Kong, China, Copyright Journal compilation © 2009 Blackwell Publishing Ltd Freshwater Biology, Volume 54 Issue 8, Pages 1720 – 1730 (April 2009)
1. Biological invasions have become a serious threat to ecosystems worldwide. Various factors can contribute to the success of biological invasion. We examined how different macrophyte food affectedfeeding and life-history traits of the invasive herbivorous snail Pomacea canaliculata, and whether differences in snail life-history traits could explain its successful infestation of agricultural and non-agricultural wetlands in Asia.
2. We tested five cultivated and five wild semi-aquatic macrophytes. Snail daily feeding rate varied substantially with plant species, ranging from 1.3% to 22% of its body mass. Snails fed with four (Amaranthus gangeticus, Apium graveolens dulce, Ipomoea aquatica and Nasturtium officinale) of the five cultivated macrophyte species exhibited high survivorship, fast growth and high fecundity. Snails fed with Colocasia esculenta, however, grew poorly, did not reproduce and eventually died.
3. Of the five wild species (Eichhornia crassipes, Ludwigia adscendens, Murdannia nudiflora, Myriophyllum aquaticum and Polygonum hydropiper), M. nudiflora supported a high snail survival, but snails had slower growth and lower fecundity than those reared on the four palatable cultivated species. Snails fed with L. adscendens grew substantially slower than those fed with M. nudiflora, and produced only a small clutch of eggs. Snails fed with E. crassipes, M. aquaticum and P. hydropiper had very low survivorship, grew very little and did not reproduce.
4. We determined six plant properties and their correlation with the feeding, growth and reproduction of the apple snails. Cultivated macrophytes in general had a higher nutritional value and lower physical and chemical defences. Phenolic content was negatively correlated with snail feeding rate, while plant nitrogen and phosphorus contents were positively correlated with snail egg production and growth, respectively.
5. These results indicate that, due to their higher nutritional value and lower chemical and physical defences, cultivated macrophytes are in general desirable for the apple snail which may partly explain its successful invasion into wet agricultural areas in Asia. This snail may also selectively graze poorly defended wild macrophytes in non-agricultural wetlands, leading to changes in floral diversity and wetland functioning. Management of this and other apple snails with similar life-history traits should thus focus on the prevention of their further spread.
Significance of the tropical fire ant Solenopsis geminata (hymenoptera: formicidae) as part of the natural enemy complex responsible for successful biological control of many tropical irrigated rice pests by M.J. Waya1 c1 and K.L. Heonga2a1 Department of Biology, Imperial College London, UK a2 International Rice Research Institute, Manila, Philippines, Bulletin of Entomological Research Cambridge University Press, 2009
Abstract. The tropical fire ant Solenopsis geminata (Fabricius) often nests very abundantly in the earthen banks (bunds) around irrigated rice fields in the tropics. Where some farmers habitually drain fields to the mud for about 3–4 days, the ants can quickly spread up to about 20 m into the fields where they collect food, including pest prey such as the eggs and young of the apple snail Pomacea caniculata (Lamarck) and insects such as lepidopterous larvae and hoppers, notably Nilaparvata lugens (Stäl) the brown planthopper (Bph) and green leafhoppers Nephotettix spp. Even in drained fields, the activity of S. geminata is restricted by rainfall in the wet season. The relatively few ant workers that forage characteristically into drained fields and on to the transplanted clumps of rice plants (hills) kill the normally few immigrant Bph adults but are initially slower acting than other species of the natural enemy complex. However, larger populations of Bph are fiercely attacked and effectively controlled by rapidly recruited ant workers; whereas, in the absence of the ant, the other natural enemies are inadequate. In normal circumstances, there is no ant recruitment in response to initially small populations of immigrant Bph and no evidence of incompatibility between ant foragers and other natural enemies such as spiders. However, when many ants are quickly and aggressively recruited to attack large populations of Bph, they temporarily displace some spiders from infested hills. It is concluded that, in suitable weather conditions and even when insecticides kill natural enemies within the rice field, periodic drainage that enables S. geminata to join the predator complex is valuable for ant-based control of pests such as snails and Lepidoptera, and especially against relatively large populations of Bph. Drainage practices to benefit ants are fully compatible with recent research, which shows that periodic drainage combats problems of ‘yield decline’ in intensively irrigated tropical rice and is also needed in South East Asia to make better use of seriously declining water supplies for irrigation.
PILA AMPULLACEA AND POMACEA CANALICULATA, AS NEW PARATENIC HOSTS OF GNATHOSTOMA SPINIGERUMby Chalit Komalamisra, Supaporn Nuamtanong and Paron Dekumyoy, Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand, Research Note, Vol 40 No. 2, March 2009
Abstract.Aquatic snails, Pila ampullacea and Pomacea canaliculata were experimentally found to be suitable paratenic hosts for advanced third-stage larvae (L3) of the nematode Gnathostoma spinigerum, the causative parasite of gnathostomiasis, or “creeping eruption,” in humans. G. spinigerum (L3) were found to be encapsulated in the tissue of the snail’s foot and itsinternal organs. The infection, intensity and survival of third-stage larvae of G. spinigerum in both species of aquatic snails are described. This is the first evidence to reveal that not only vertebrates but also invertebrates (snails) can serve as paratenic hosts to this parasite. Aquatic snails are one of several sources of human gnathostomiasis in Thailand.
PINK EGGS AND SNAILS: FIELD OVIPOSITION PATTERNS OF POMACEA INSULARUM THAT MAY IDENTIFY WETLANDS OR SHALLOW LAKES SUSCEPTIBLE TO INVASION by James P. McDonough*, Colin H. Kyle and Romi L. Burks, Department of Biology, Southwestern University, Georgetown, TX 78626, Texas Academy of Sciences Meeting, March 6, 2009
Abstract. Wetlands and shallow lakes are among the world’s most threatened ecosystems. The spread of exotic invasive species represents one of the greatest threats to wetland communities throughout Texas. Aquatic invasive mollusks represent some of the most dangerous organisms to wetlands due to their high rates of reproduction and consumption. A recently identified invasive species of applesnail in Texas, Pomacea insularum, exhibits these alarming characteristics. As fecundity serves as the best indicator for invasive potential, understanding P. insularum’s reproductive behavior is key to predicting how P. insularum will spread within Texas and along the gulf coast. Identification of specific egg laying trends in P. insularum will play a key role in predicting future areas of invasion. Specific characteristics within Texas wetlands and shallow lakes may facilitate the invasion process of P. insularum by providing females with beneficial egg laying (ovipositing) conditions. To investigate this possibility, we studied P. insularum oviposition behavior in an invasive population found within Armand Bayou Nature Preserve (Houston, TX). Surveys of ovipositing sites revealed clear egg laying substrate preferences for P. insularum. Our results showed that P. insularum prefers large aquatic macrophytes as substrates for ovipositing, specifically emergent macrophytes such as Colocasia esculenta (i.e. Taro) and that this preference persists across seasons and years. Wetlands and shallow lakes surrounded by large emergent macrophytes likely provide preferred ovipositing sites for P. insularum and may possibly facilitate their invasion into new aquatic ecosystems.
LOCATION, LOCATION, LOCATION: LABORATORY OVIPOSITION PREFERENCES OF THE EXOTIC, INVASIVE APPLESNAIL POMACEA INSULARUMbyColin H. Kyle.*, James P. McDonough and Romi L. Burks, Department of Biology, Southwestern University, Georgetown, TX 78626, Texas Academy of Sciences Meeting, March 6, 2009
Abstract. By investigating spatial structure of an invasive population, ecologists can potentially determine population control methods. This technique may prove useful for combating the exotic invasive aquatic applesnail Pomacea insularum, recently found along the Gulf Coast. In Houston, Texas, researchers find P. insularum in clumped distributions around emergent structures. P. insularum deposits bright pink egg clutches above the water’s surface on waterside objects. The snail’s reliance on emergent objects for reproduction may attract them to preferred structures. To discover mechanisms underlying population distribution, we designed three lab experiments investigating what specific object qualities attract P. insularum (substrate material; substrate structure; exotic vs. native Texas plants). To better understand reproduction, we examined characteristics (height above water, dimensions, mass, approximate volume) and hatching efficiencies of clutches laid in experiments. We compared characteristics of lab clutches to eggs found in Houston. We found P. insularum preferentially oviposited on plants and ignored wood, metal or plastic (p<0.01), chose round rather than flat (p<0.001) but did not differentiate between tall or short structures (p>0.05), and preferred exotic (Colocasia esculenta) to native (Pontederia cordata) Texas plants (p<0.001). Interactions between P. insularum and C. esculenta indicate potential invasion meltdown in Houston. Clutch characteristics comparisons revealed similarities between lab and field reproduction (p>0.05), validating our ability to apply our lab results to field populations. We conclude that P. insularum clusters around emergent plants, specifically C. esculenta, due to oviposition preferences for these objects. Removing egg clutches from areas dense with C. esculenta should slow P. insularum spread and damage.
WETTER ISN’T BETTER: EFFECTS OF DISTURBANCE ON POMACEA INSULARUM HATCHING EFFICIENCY byMatthew K. Trawick* and Romi L. Burks, Department of Biology, Southwestern University, Georgetown, TX 78626, Texas Academy of Sciences Meeting, March 6, 2009
Abstract. The ability to successfully reproduce in a given environment represents one of the most important determinants of an organism’s invasive capability. Reproductive plasticity and fecundity play critical roles for invasive success in mollusks. Pomacea insularum, a large freshwater gastropod native to South America that has successfully invaded several Texas waterways through multiple introductions, puts forth great effort to oviposit each egg clutch (often containing more than 1000 eggs) well above the waterline, where it fully dries before hatching. Our experiments sought to determine the effects of water exposure to egg clutch hatching efficiency, and to compare short-term survival of disturbed vs. not disturbed hatchlings. In order to test the effects of disturbance on the hatching efficiencies of P. insularum egg clutches, we subjected egg clutches collected from Armand Bayou (Pasadena, TX) to water exposure at two levels of intensity: high, consisting of full submergence, and low and three levels of frequency (low, medium, high). We found that clutches that we completely submerged for 24 hours/day did not hatch, nor did clutches that floated on water for 24 hours/day. Water exposure also significantly affected hatching efficiency at other frequencies. To test short-term survival, we pooled hatchlings hatched under disturbed (i.e. submerged for 3 hours every other day) conditions and undisturbed conditions. Results are forthcoming for this second experiment. Survival, and subsequently invasive capability, does seem dependent on water exposure during egg clutch development.
Reaction norms of size and age at maturity of Pomacea canaliculata (Gastropoda: Ampullariidae) under a gradient of food deprivationby Nicolás E. Tamburi and Pablo R. Martín, Laboratorio de Ecología, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, 8000 Bahía Blanca, Argentina, Journal of Molluscan Studies 75(1):19-26 (February 2009)
Abstract. Pomacea canaliculata, an apple snail native to South America,has become a serious pest of aquatic crops and a promoter ofecosystem changes in natural wetlands worldwide. Its successas an invader has been attributed to its great phenotypic plasticityin life-history traits. Our aims were to determine the reactionnorms of size and age at maturity under a gradient of food deprivation.Full sibling experimental snails were reared in isolation fromhatching and maintained until maturity under seven differentlevels of relative food deprivation based on size-specific ingestionrates. To detect the onset of sexual activity of experimentalsnails, fully mature virgin snails reared in the laboratorywere used as consorts. The reaction norms for age and size atmaturity of P. canaliculata showed marked sexual dimorphism.Shell length was the main component of variation in the malereaction norms for both copulation and egg-laying by femaleconsorts, whereas age was the main component of variation forfemales. Irrespective of the intensity of food deprivation,males mature at the same age at the expense of size, since sizeis apparently irrelevant in the access to females and male fitnesscan be maximized through fast maturation. In contrast, a minimumsize is required for females to reach maturity, perhaps as aresult of their higher reproductive costs. The highly dimorphicreaction norms lead to an increasing lag between male and femalematurity as deprivation increases; in temperate regions, malesborn early in the reproductive season would mature in the sameseason irrespective of food availability, while most femaleswould have to overwinter before attaining sexual maturity inunproductive habitats or those dominated by unpalatable macrophytes.The great life-history plasticity reported in invaded areascould be a heritage from populations in the native range.
Distribution of heavy metal concentrations in the different soft tissues of the freshwater snail Pomacea insularum and sediments collected from polluted and unpolluted sites from Malaysia by C. K. Yap, F. B. Edward, B. H. Pang, A. Ismail, S. G. Tan, H. A. Jambari, Department of Biology, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia, Toxicological & Environmental Chemistry, Volume 91, Issue 1, February 2009
Abstract. Pomacea insularum were collected from polluted and unpolluted freshwater ecosystems in Malaysia. Besides the shells, the soft tissues were dissected and pooled into cephalic tentacle, foot, mantle, operculum, digestive tract, penial sac, lung sac, and remainder. These tissues were analyzed for the concentrations of Cu, Cd, Fe, Ni, and Zn. The present work resulted in three interesting findings. First, the concentrations of Cu, Cd, Fe, and Zn found in most of the different parts of P. insularum collected from the polluted Juru River were significantly (P < 0.05) higher than those found in the snails from the other four sites. Second, positive and significant correlation coefficients were found for sediment-lung sac for Cd, Fe, and Zn while sediment-digestive tract for Cu. These correlation results indicated that lung sacs could reflect the environmental concentrations of Cd, Fe, and Zn, while the digestive tract could do the same for Cu. Third, the different concentrations of heavy metals found in the different parts indicated different metal regulation and binding sites in these organs. The significant correlation coefficients between different tissues indicated that they might be caused by similar metal regulation and sequestration. Based on the above findings, P. insularum are a potential biomonitor of Cd, Cu, Fe, and Zn pollution in freshwater ecosystems.
Invasive Snails and an Emerging Infectious Disease: Results from the First National Survey on Angiostrongylus cantonensis in China byShan Lv,1,2 Yi Zhang,1 He-Xiang Liu,1 Ling Hu,1 Kun Yang,1 Peter Steinmann,1,2 Zhao Chen,3 Li-Ying Wang,3 Jürg Utzinger,2 and Xiao-Nong Zhou1*1National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People’s Republic of China, 2Department of Public Health and Epidemiology, Swiss Tropical Institute, Basel, Switzerland, 3Ministry of Health of China, Beijing, People’s Republic of China,PLoS Negl Trop Dis. 2009 February; 3(2): e368, February 2009
Abstract. Eosinophilic meningitis is caused by the rat lungworm (Angiostrongylus cantonensis). This parasite is endemic in Southeast Asia, Australia, the Caribbean, and on Pacific Islands. Moreover, the disease is emerging in mainland China, which might be related to the spread of two invasive snail species (Achatina fulica and Pomacea canaliculata). Thus far, the biggest angiostrongyliasis outbreak in China occurred in 2006 in Beijing, involving 160 patients. However, detailed information about the national distribution of A. cantonensis and its intermediate hosts is still lacking, and the importance of the two invasive snail species for disease transmission is not well understood. Therefore, a national survey on the distribution of A. cantonensis and its intermediate hosts in China was carried out in 2006/2007. It was found that A. fulica and P. canaliculata were implicated in most angiostrongyliasis outbreaks, and that the distribution of A. cantonensis closely matched that of these snails. The two invasive snail species facilitated the expansion of the parasite, thus probably leading to the emergence of angiostrongyliasis, a previously rare disease, in mainland China.
Introduction, distribution, spread, and impacts of exotic freshwater gastropods in Texas by Alexander Y. Karatayev1, Lyubov E. Burlakova1, 2, Vadim A. Karatayev3 and Dianna K. Padilla4 1Great Lakes Center, Buffalo State College, 1300 Elmwood Avenue, Buffalo, NY 14222, USA, 2 The Research Foundation of The State University of New York, Buffalo State College, Office of Sponsored Programs, 1300 Elmwood Avenue, Bishop Hall B17, Buffalo, NY 14222-1095, USA, 3 City Honors School, 186 East North Street, Buffalo, NY 14204, USA, Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY 11794-5245, USA, Hydrobiologia, Volume 619, Number 1, February 2009
Abstract. We examined the patterns of distribution, vectors of introduction, and potential ecological impacts of freshwater exotic species in Texas over the last 45 years. Currently, five species of exotic gastropods are established: channeled-type applesnail (Pomacea insularum), red-rim melania (Melanoides tuberculatus), quilted melania (Tarebia granifera), giant rams-horn snail (Marisa cornuarietis), and Chinese mystery snail (Cipangopaludinachinensis). In contrast to the northern part of the US, where shipping appears to be the most important vector for the introduction of aquatic invasive species, aquarium and ornamental trade dominated among unintentional vectors of introduction of all freshwater exotics in Texas, resulting in different patterns of distribution, spread, and ecological impacts. The rate of spread of exotic gastropods in Texas varied from 39 waterbodies colonized over 18 years for P. insularum to only three waterbodies during last 45 years for C.chinensis. Four of five exotic gastropods were found in highly vulnerable aquifer-fed springs and rivers, which contain numerous endemic and endangered species. The fifth species, Pomacea insularum, is an agricultural pest. Potential negative ecological effects of exotic gastropods include impacts on wetlands and wetland restoration, competitive exclusion of native snails, and the introduction of exotic parasites, trematodes, which could infect fish and waterfowl, including federally protected species. Aquifer springs with stable temperature regimes are refuges for both cold and warm intolerant species.
Field observations of the alarm response to crushed conspecifics in the freshwater snail Pomacea canaliculata: effects of habitat, vegetation, and body size by Kahori Aizaki and Yoichi Yusa, Faculty of Science, Nara Women’s University, Japan, Journal of Ethology, Volume 27, Number 1, January 2009
Abstract. The freshwater snail Pomacea canaliculata shows alarm responses to chemical cues released from injured conspecifics, but its behavioural responses in the field are unknown. We investigated effects of habitat (canals or paddy fields), vegetation, and body size on alarm responses in the field. Snails responded to crushed conspecifics within 4 min by burying themselves, but the proportions of self-buried snails were generally lower (0–28% depending on experiments) than those reported in the laboratory. Snails not only showed the alarm response, but also frequently fed on crushed conspecifics. There were no influences of habitat or body size on the proportions of individuals showing the alarm response. Nevertheless, in paddy fields with high-density vegetation a higher proportion of snails showed the alarm response than in paddy fields with low-density vegetation.
Angiostrongylus cantonensis: Morphological and Behavioral Investigation within the Freshwater Snail Pomacea canaliculata by Lv S, Zhang Y, Lui H X, Zhang C W, Steinmann P, Zhou X N, Utzinger J, Department of Public Health and Epidemiology, Swiss Tropical Institute, Parasitology Res. (January 27, 2009)
Abstract. An infection with Angiostrongylus cantonensis, the main causative agent for human eosinophilic encephalitis, can be acquired through the consumption of the freshwater snail Pomacea canaliculata. This snail also provides a suitable model to study the developmental morphology and behavior of A. cantonensis larvae, facilitated by the snail’s distinct lung structure. We used microanatomy for studying the natural appearance and behavior of A. cantonensis larvae while developing within P. canaliculata. The distribution of refractile granules in the larval body and characteristic head structures changed during the developmental cycle. Two well-developed, rod-like structures with expanded knob-like tips at the anterior part were observed under the buccal cavity as early as the late second developmental stage. A “T”-shaped structure at the anterior end and its tenacity distinguished the outer sheath from that shed during the second molting. Early first-stage larvae obtained from fresh rat feces are free moving and characterized by a coiled tail, whereas a mellifluous “Q”-movement was the behavioral trait of third-stage A. cantonensis larvae outside the host tissue. In combination, the distribution of refractive granules, distinct head features, variations in sheaths, and behavioral characteristics can be utilized for differentiation of larval stages, and for distinguishing A. cantonensis larvae from those of other free-living nematodes.
Ensiling of Golden Apple Snails (Pomacea canaliculata) and Growth Performance of African Catfish (Clarias gariepinus) Fingerlings Fed Diets with Raw and Ensiled GAS as a Protein Source by O Phonekhampheng, L T Hung and J E Lindberg, Livestock Research for Rural Development, Vol. 21 (January 2009)
Abstract. The influence of ensiling Golden Apple snails (GAS) on nutritional and biochemical traits, and the growth performance of African catfish (Clarias gariepinus) fingerlings fed diets where fish meal was replaced with raw or ensiled GAS as protein source was studied. Raw GAS was ensiled without (control) and with addition of citric acid or sugar cane molasses. The dry matter (DM) content in ensiled GAS decreased (P<0.05), and the pH value and ammonia nitrogen content increased (P15 % in DM) that maintained a brownish-yellow colour and a nice smell for the whole ensiling (28 d) period. A control diet with fish meal and three experimental diets, where fish meal was replaced with raw or ensiled GAS, were formulated and fed to African catfish fingerlings. GAS was ensiled with 5 % citric acid or 20 % sugar cane molasses. The growth performance and feed consumption was recorded for a period of 6 weeks. There were no differences (P>0.05) in growth performance, feed and protein utilization, and whole body composition between treatments. In conclusion, protein from raw and ensiled GAS can completely replace fish meal in diets for African catfish fingerlings under tropical conditions without negative effects on growth performance and feed utilization.
Life cycle of the apple snail Pomacea canaliculata (Caenogastropoda: Ampullariidae) inhabiting Japanese paddy fields by YOSHIDA Kazuhiro, HOSHIKAWA Kazuo, WADA Takashi, and YUSA Yoichi, Applied Entomology and Zoology , vol. 44, No. 3, pp. 465-474 (2009)
Abstract. The life cycle of the apple snail Pomacea canaliculata was monitored over 2- and 1-year periods in Nara (cold district) and Kumamoto (warm district), respectively. The life cycles were similar in both districts: most hatchlings appeared after August, and although some had grown to ≥20mm by autumn, the majority of juveniles remained <20 mm. The survival rate over winter was very low (< 1 %) in Nara, and moderately low (9%) in Kumamoto. After winter, survivors grew rapidly with low mortality, reproduced actively in summer, and most died during the following winter. The survival rate during mid-term drying (drying of fields for about 2 weeks in summer) in Nara was high (ca. 90%) in both years. In Nara, snail density after winter decreased to 1/43 of that in Kumamoto, but survivors in Nara grew larger and laid more eggs. Due to these effects, egg density in July, and also snail density in September, in Nara recovered to ca. 1/3 of that in Kumamoto.
Molluscicidal Activity of Ethanol Extracts from Nerium indicum Leaves on Pomacea canaliculata
by Dong, D. Q., Chen, J. M., Yu, X. P., Chen, L. Z., Chinese Journal of Pesticide Science [Chin. J. Pestic. Sci.]. Vol. 11, no. 1, pp. 109-113. (2009)
In order to find molluscicidal active components from Nerium indicum leaves on golden apple snail (GAS), Pomacea canaliculata (Lamarck), the lethal and inhibition effect of ethanol crude extracts and component I from N. indicum leaves against different-day old GAS was conducted by the snail-immersed method. The results showed that the LC sub(50) value of component I against GAS of 10, 30 and 50 days old were 2.86, 5.87 and 8.68 mg/L on 6 h after treatment, respectively; and were 0.98, 2.31 and 3.16 mg/L on 24 h, respectively. Treated with 2 mg/L of component I for 24 h, the mortality of 10 d-old GAS reached 100%. When treated with 100 mg/L ethanol crude extracts for 72 h, the mortality of 10 d-old and 30 d-old GAS all reached 100%; and the mortality of 50 d-old GAS also reached 100% when treated with 200 mg/L extract for 120 h. Both ethanol crude extract and component I had no inhibitory effect on activities of GAS, but promoted upward climbing of GAS.
The Potential of the Invasive Snail Pomacea canaliculata as a Predator of Various Life-Stages of Five Species of Freshwater Snails by King-Lun Kwong1, Robert K.Y. Chan2 & Jian-Wen Qiu,1 Department of Biology, Hong Kong Baptist University, Hong Kong, P. R. China,2 Department of Physics, Hong Kong Baptist University, Hong Kong, P. R. China, Malacologia 51(2):343-356. 2009
Abstract. The invasive apple snail Pomacea canaliculata is known as an omnivorous species, but there are only few reports of its predation. This study examined the potential of this snail as a predator of common freshwater snails in southern China. Laboratory experiments were conducted to quantify the damage of the apple snail to both early stages (eggs and/or neonates) and adults of five species of freshwater snails (Austropeplea ollula, Biomphalaria straminea, Melanoides tuberculata, Physa acuta, Sinotaia quadrata). The apple snail caused significant mortality to all of the early stages of the five snails, as well as adults of the pulmonates A. ollula, B. straminea and P. acuta, but did not consume adults of the prosobranchs M. tuberculata and S. quadrata. Such differential survival of the prey might be explained by differences in shell hardness and structure, as the adult prosobranchs were well protected by a hard shell and an operculum, whereas the pulmonates had a relatively fragile shell and lacked an operculum. The apple snail was unable to detect its prey from a distance, but it crawled quickly, which could create opportunities for direct contact with potential prey. Apple snails may therefore influence invaded ecosystems through predation on other freshwater snails.
EFFECTS OF THE INVASIVE EXOTIC APPLE SNAIL (Pomacea insularum) ON THE SNAIL KITE (Rostrhamus sociabilis plumbeus) IN FLORIDA, USA by Christopher Cattau, Master’s Thesis, University of Florida, 2008
Abstract. The Snail Kite (Rostrhamus sociabilis plumbeus) is an endangered raptor in the U.S. that exhibits an extreme form of dietary specialization, feeding almost exclusively on one species of freshwater snail, the Florida Apple Snail (Pomacea paludosa Say). Lake Tohopekaliga, one of the few remaining wetland fragments utilized by the snail kite in Florida, recently experienced an infestation of the invasive exotic Island Apple Snail (Pomacea insularum), which is relatively larger (length, x = 63.5 mm; weight, x = 56.8 g) than the native apple snail (length, x = 37.6 mm; weight, x = 15.9 g). This relative size difference raised questions about the ability of kites (especially juveniles) to negotiate exotic snails, and given the sensitivity of the kite population to recruitment, we conducted a comparative observational study to elucidate the effects of the exotic apple snail on snail kite foraging behavior, energetics, nest success, and survival. Relative to native snails, we found that exotic snails require longer handling times (for adults, 302 vs. 72 seconds; for juveniles, 496 vs. 97 seconds), lead to increased drop rates (for adults, 0.21 vs. 0.02; for juveniles, 0.33 vs. 0.06), and result in depressed capture rates (for adults, 1.09 vs. 3.30 snails/hour; for juveniles, 0.78 vs. 3.46 snails/hour); however, we also found that exotic snails provide more energy than natives (12.92 vs. 4.84 kcal/snail). Consequently, the effects of the exotic snail on foraging behavior do not have negative energetic repercussions for adult kites. In fact, we found that adult kites are attracted to Lake Tohopekaliga and that the relative contribution of the lake to the range-wide nesting effort increased from 6% to 33% after the invasion of the exotic snail. Conversely, the effects of the exotic snail on juvenile foraging behavior can lead to insufficient daily energy balances and may suppress juvenile survival. Given the critically endangered status of the snail kite and the propensity of the exotic apple snail to spread, this work suggests that serious management and conservation initiatives that address the exotic apple snail may be necessary to prevent further deleterious consequences for the kite population in Florida.
Backbone Cyclised Peptides from Plants Show Molluscicidal Activity against the Rice Pest Pomacea canaliculata (Golden Apple Snail) by Manuel Rey R. Plan†, Ivana Saska†, Arsenia G. Cagauan‡ and David J. Craik, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia, and Freshwater Aquaculture Center, Central Luzon State University, Mu oz, Nueva Ecija, Philippines, J. Agric. Food Chem.,56 (13), pp 5237–5241 (2008)
Abstract. Golden apple snails (Pomacea canaliculata) are serious pests of rice in South East Asia. Cyclotides are backbone cyclized peptides produced by plants from Rubiaceae and Violaceae. In this study, we investigated the molluscicidal activity of cyclotides against golden apple snails. Crude cyclotide extracts from both Oldenlandia affinis and Viola odorata plants showed molluscicidal activity comparable to the synthetic molluscicide metaldehyde. Individual cyclotides from each extract demonstrated a range of molluscicidal activities. The cyclotides cycloviolacin O1, kalata B1, and kalata B2 were more toxic to golden apple snails than metaldehyde, while kalata B7 and kalata B8 did not cause significant mortality. The toxicity of the cyclotide kalata B2 on a nontarget species, the Nile tilapia (Oreochromis niloticus), was three times lower than the common piscicide rotenone. Our findings suggest that the existing diversity of cyclotides in plants could be used to develop natural molluscicides.
Accumulation of Copper by Golden Apple Snail Pomacea canaliculata Lamarck by Silvia C. Peña1 and Glorina N. Pocsidio2, 11Institute of Environmental Science and Meteorology, University of the Philippines, Diliman, Quezon City, Philippines, 2Institute of Biology, University of the Philippines, Diliman, Quezon City, Philippines, Philippine Journal of Science, December 2008
Abstract. The golden apple snail (Pomacea canaliculata) accumulated copper (Cu) from 20, 30, 45, 67.5, and 101.25 µg Cu/L but showed behavioral regulation at 67.5 and 101.25 µg Cu/L. Bioaccumulation factor (1.04), biotransference factor (1.01), assimilation efficiency (89%), and accumulation rate (8.97 µg Cu/g/day) were high in 7 days of exposure. Copper accumulation from the dissolved copper, food, and sediment by the organs such as kidney, digestive gland, foot, and gills were not significantly different from one another. But the Cu accumulation in dissolved Cu and sediment by the whole soft tissue were significantly higher than those from the food and the control. Gill was the main route of exposure for dissolved Cu. Results obtained favored golden apple snail as Cu biomonitor at sublethal concentrations (0-45 µg Cu/L) using its whole tissue for analysis. It could be used as biomarker at high concentrations.
Fecundity of the exotic applesnail, Pomacea insularum by Matthew A. Barnes, Rebecca K. Fordham, and Romi L. Burks of Southwestern University, Georgetown, Texas and Jennifer J. Hand of University of Houston-Clear Lake, Houston, Texas, Journal of the North American Benthological Society, 27(3):738–745, July 2008
Abstract. International trade frequently moves mollusks around the globe, thereby increasing their opportunity to cause ecological and economic damage. Recent genetic studies have confirmed the identity of South American applesnails (Pomacea insularum) in the southeastern US, but limited literature exists on this species. Understanding fecundity provides direct insight into the invasive potential of mollusks. Our study documents P. insularum fecundity in Texas and offers comparisons with the closely related global invader P. canaliculata. We quantified P. insularum clutch and hatchling physical characteristics and examined field and laboratory hatching success. Clutches contained thousands of eggs (mean = 2064 eggs), and clutch size tended to increase over the reproductive season. Clutches exhibited average field and laboratory hatching efficiencies (number of hatchlings/total number of eggs) near 70 and 30%, respectively. Notably, several clutches hatched at 80% or higher in the field. Exotic P. insularum deposit more eggs/clutch than the related invader P. canaliculata, but we do not yet know how seasonal hatching efficiencies compare. However, even with a conservative estimate of 1 to 10% survival to adulthood, the average P. insularum clutch yields 14 to 144 new applesnails. The high fecundity of P. insularum translates into considerable ecological impact because adult females can contribute >1 clutch/wk over an extended growing season in the southeastern US. The need for research has increased with the emergence of P. insularum populations in the fragile Florida Everglades. We advocate life-history studies like ours to help understand the invasion potential of applesnails and other invasive mollusks.
DENSITY EFFECTS OF NATIVE AND EXOTIC SNAILS ON GROWTH IN JUVENILE APPLE SNAILS POMACEA PALUDOSA (GASTROPODA: AMPULLARIIDAE): A LABORATORY EXPERIMENT by S.L. Conner, C.M. Pomory and P.C. Darby, Department of Biology, University of West Florida, Pensacola, FL 32514, USA, Published by Oxford Press on behalf of The Malacological Society of London, June 2008
Abstract. Pomacea paludosa (native Florida apple snail) is found in wetlandsin the southeastern United States. Pomacea insularum is an exoticapple snail which has invaded wetlands in Florida and co-occurswith P. paludosa. The effect of changes in density on growthin native juvenile snails was studied by manipulating nativejuvenile density, native adult density and exotic adult densityin a set of laboratory experiments. Growth decreased when nativejuvenile densities (without adults) increased from four to eightsnails per 38-l aquarium. The presence of adults of either speciesdecreased juvenile growth and also decreased juvenile survival.One exotic adult had the equivalent effect of three to fournative adults. Based on the response of native juveniles toexotic adults, populations of the native apple snail P. paludosacould be negatively impacted by expansion of the exotic snailP. insularum.
THE POTENTIAL FOR AQUACULTURE TO SUPPORT THE RECOVERY OF APPLE SNAIL POPULATIONS IN FLORIDA WETLANDS AND LAKES by Rachael L. Pierce1, Philip C. Darby 2, Amber L. Shawl3, Megan Davis3,1 South Florida Water Management District, 2 University of West Florida, 3 Harbor Branch Oceanographic Institute at Florida Atlantic University, Florida Lake Management Society Annual Conference, Sandestin, Florida, June 2 – 5, 2008
Abstract. The Florida apple snail (Pomacea paludosa Say) is a critical component of Florida freshwater lakes and wetlands, serving as prey to many aquatic and avian predators, including the endangered Snail Kite (Rostrahmus socialibilis). The snail kite utilizes a network of freshwater wetlands and lakes that are influenced by natural hydrologic cycles as well as water management. In the last eight years, habitat quality and snail availability has been substantially reduced, contributing to the decline of the kite population. Natural reestablishment of wild snail populations to support kite foraging may take many years. The South Florida Water Management District (SFWMD), in cooperation with Harbor Branch Oceanographic Institute (HBOI), has implemented a pilot level study to explore the possibility of raising snails via aquaculture in order to speed up the recovery of decimated snail populations through restocking. HBOI has successfully raised snails hatched from eggs collected in the field, and they have produced two generations of cultured snails. Hatch success, egg size, survival and other measures of snail viability are being assessed and will be compared to data from field studies. In addition, questions regarding genetics and how to scale up the culture to levels applicable to restoring large marsh areas will be discussed. A pilot level release is planned for spring 2008, in which the efficacy of a restocking effort will be examined. The snail culture project will be discussed in the context of other SFWMD approaches to restoring habitat quality and hydrologic conditions to support the recovery of snails and their predators.
COCONUT OIL AS POTENTIAL CONTROL OF GOLDEN SNAILS (Pomacea canalicuta) INFESTING RICE PLANTS By Maryjane A. Naranjo, Loueli A. Talam, Arhel S. Tillo, and Ronald A. Vale, Advisers: Ms. Marites A. Caguindangan, Ms. Gloria S.Sale, Plaridel, Midamis Occidental, June 2008
Abstract. An investigation was conducted to determine the potential of coconut oil as an alternative control of golden snails (Pomacea canalicuta) by the inhibitory action of fresh coconut oil on hatching of golden snail eggs. The inhibitory action of a commercial pesticide (Porsnail) and that of complete immersion in water to the hatching of golden snail eggs was also determined. Results showed that coconut oil could inhibit the hatching of 82.2% of the golden snail eggs. Results remained unchanged within an observation period of ninety (90) days. One hundred percent (100%) of eggs in the control and the other two experimental setups hatched.
The color, length and width of leaves were used as parameters in determining the effect of coconut oil on the growth of rice plants. No noticeable difference was observed between rice plants not treated with coconut oil and rice plants sprayed with coconut oil in terms of color, length and width of leaves. Hence, the inhibitory action of coconut oil on the hatching of golden snail eggs can be utilized as control of golden snails without hampering the growth of rice plants. The product of this research offers an alternative control of golden snails infesting rice plants utilizing coconut oil which is common, abundant, natural and non-toxic. It would enable farmers to start the control at the incubation period of the golden snail eggs and to treat only specific areas in the rice fields where golden snail egg masses are present instead of the whole field.
Factors affecting hatching success of golden apple snail eggs: effects of water immersion and cannibalism by Katherine C. Horn, Sally D. Johnson, Kate M. Boles, Anthony Moore, Evan Siemann, Christopher A. Gabler, Wetlands, Vol. 28, Issue 2, pg(s) 544-549, June 2008
Abstract. The golden apple snail (Pomacea maculata Perry) is an invasive species that lays its eggs out of water but is otherwise aquatic. To investigate this behavior and potential management techniques, we conducted experiments to examine the physical effects of immersion and underwater egg predation on hatching success. Predation on submerged eggs by P. maculata adults reduced hatching success by 99%. In predator-free conditions, hatching success was reduced 75% by immersion in water and was negatively correlated with time submerged. Our results suggest that both underwater egg predation and low immersion tolerance may be exploited to limit the spread of P. maculata.
Shell morphology and physiological tolerances of the exotic apple snails Pomacea insularum and Pomacea canaliculata, in Florida, by Jennifer L. Bernatis, UF, Fisheries and Aquatic Sciences, University of Florida and Florida Fish and Wildlife Commission, Gainesville, FL, Proceedings of the North American Benthological Society, Grand Rapids, Michigan, May 28, 2008
Abstract. The South American apple snails Pomacea canaliculata and Pomacea insularum have been implicated in the alteration of Florida aquatic ecosystems. However, the invasive Pomacea species truly responsible for the damage is unknown; recent genetic work demonstrated inaccuracies in the original species identifications. The purpose of this research was twofold: 1) determine differences in shell morphology between the species and, 2) determine physiological tolerances to environmental stressors. An analysis of 45 shell dimension relationships showed significant differences: adults (35 of 45 pairs, P < 0.05), and juveniles (33 of 45 pairs, P < 0.05); total width comparison for hatchlings was also significantly different. Tolerances of salinity, desiccation, pH, and starvation were tested. Salinity was tolerated up to 12 ppt for P. canaliculata and 8 ppt for P. insularum. Desiccation tolerance was at least 1 year for adults, up to 5 months for juveniles, and 7 weeks for hatchlings. Both species tolerate pH ranges of 5.5 – 10.5. P. insularum adults were less susceptible to starvation, however, juvenile P. canaliculata tolerated longer periods of starvation than juvenile P. insularum. Overall, the results of this research provide a mechanism for field identification and the physiological understanding necessary to determine potential effects on aquatic ecosystems.
Effects of predation on the exotic freshwater snail Pomacea canaliculata by the indigenous turtle Chinemys reevesii by Haruko Yoshie and Yoichi Yusa, Faculty of Science, Nara Women’s University, Applied Entomology and Zoology, Vol. 43, No. 4, p. 475-482 (May 2008)
Abstract. We studied the predatory potential of the turtle Chinemys reevesii on the apple snail Pomacea canaliculata using two series of experiments. First, we investigated the relationship between turtle body size and the maximum size of snails consumed over a period of 3 days within 0.37 m2 containers. The maximum snail size consumed was positively related with turtle size. Secondly, we investigated the predation of snails by turtles over a period of 8 weeks. We released 200 snails (10–30 mm shell height) and an adult turtle (155–183 mm carapace length) into each of two 2.08 m2 plots with soil and rice plants. Subsequently, snail density was monitored every week and 200 snails were added to low density plots up to twice a week. Two control plots with the same initial density of snails but without turtles were also monitored. The density and survival rate of snails were lower in plots with a turtle than in control plots. We estimated that a single turtle consumed >2,000 snails in 8 weeks. In addition, the biomass of duckweed (given as food for snails) was greater in turtle plots than in control plots, suggesting that the presence of turtles had an indirect effect on weed.
Introduction and Colonization of Non-native Apple Snails in Everglades National Park by Zachary W. Fratto, Jeffrey L. Kline and Ray W. Snow,National Park Service, Everglades National Park, South Florida Natural Resources Center, Homestead, FL, Greater Everglades Ecosystem Restoration: Planning, Policy and Science Meeting, Naples, FL, 2008
Abstract. In May of 2005, the non-native island apple snail Pomacea insularum and spiketop apple snail P. diffusa, were detected at the northern boundary of Everglades National Park (ENP). After initialobservations, ENP staff began to monitor the distribution and abundance of these two species. P. diffusa appears to have a limited distribution in northern Northeast Shark Slough but moremonitoring is necessary. P. insularum have spread between S-12B and S-12C water controlstructures on the Old Tamiami canal, were detected upstream in the L-29 canal, and downstreamin the Shark Valley Canal and associated marshes. Field biologist surveyed and removed eggmasses in the Old Tamiami Canal every 10-14 days. During the months of May to December of2005, 512 P. insularum egg masses and 19 live adults were removed. In 2006, 2,687 egg massesand 31 adult snails were removed. In 2007, 1,024 egg masses and 17 snails were removed.Effects of the colonization of P. insularum and P. diffusa in ENP are still unknown. Previousstudies of introduced Pomacea spp. suggest that they have the ability to consume large amountsof aquatic vegetation and may cause detrimental impacts to aquatic ecosystems. Furthermonitoring, management, and research on non-native apple snails is needed to determine effectson native fauna and flora of Everglades’ marshes and possible control or eradication strategies.
Ecological Windows of Opportunity for Florida Apple Snail Recruitment byPhilip C. Darby Department of Biology, University of West Florida, Pensacola, FL, Greater Everglades Ecosystem Restoration: Planning, Policy and Science Meeting, Naples, FL, 2008
Abstract. The Florida apple snail (Pomacea paludosa Say) has a life history adapted to water level fluctuations, including drying events, which occur in their 12-18 month life span. A myriad of predators consume the snail, and they have been identified as a barometer of wetland ecosystem health in the Greater Everglades Ecosystem. Through several field and lab studies, we have studied their demography with an emphasis on how water depths and the timing of water level fluctuations impact survival, reproduction and growth. In an analysis of our data and that from other investigators, we find ~80% of annual egg cluster production occurs in April-June. During this critical period, water levels under natural conditions typically recede or remain relatively stable. Other published studies indicate that these conditions promote egg production. If a drying event occurs, no egg cluster production occurs, so in those years we expect a reduction in overall egg cluster production. In the context of the opposite hydrologic extreme, we have recently acquired data that shows high water, especially in March-May, suppresses egg production. High water (depths > 70 cm) in WCA3A resulted in egg production approximately 10% of the production where we found similar snail densities but where water depths where <40 cm. In years with relatively high water conditions, the field egg index (eggs produced per snail), falls below 1.0. When depths fall below ≈40 cm, the egg index ranges from 2 to 11. [We have additional analyses to complete.] Through previously published size-frequency distributions and our own laboratory data on snail growth rates, we have identified a critical post-hatch growth period for hatchling snails to survive an ensuing dry down. Snails with shells <20 mm shell width exhibit higher rates ofmortality in dry conditions compared to adult snails. Consequently, the timing of dry downs determines the opportunity for juvenile snail growth that has direct bearing on survival (and therefore overall annual recruitment). As with egg cluster production, we also have data (albeit limited) that indicates high water suppresses snail growth. Water temperatures below approximately 21°C results in significant declines in general activity and consequently reproductive behavior. By combining temperature data with information on hydrologic conditions, we have constructed a conceptual model of the ecological window of opportunity for apple snail recruitment. This model will be interpreted in the context of water management schedules and restoration activities in the Greater Everglades Ecosystem.
• Apple snail recruitment is sensitive to a number of environmental conditions
• We have developed a conceptual model to define the conditions that promote recruitment
• Our findings have direct implications for water management and Everglades restoration.
Determinants Of the Distribution Of Apple Snails In Hong Kong Two Decades After Their Initial Invasion by King-Lun Kwong1, Pak-Ki Wong1, Sam S. S. Lau2, and Jain-Wen Qiu1,* , Department of Biology, Hong Kong Baptist University, Hong Kong, P. R. China 2Environmental Conservation Studies, College of International Education, Hong Kong Baptist University, Hong Kong, P. R. China, Malacologia 50(1):293-302, 2008
Abstract. This study examined the relative importance of environmental factors and geographic isolation on the distribution of apple snails in Hong Kong two decades after their invasion from South America. A survey of 61 sites was conducted to collect apple snails and measure 18 environmental parameters known to influence mollusk distribution. Identification of specimens collected in our study was aided by analysis of DNA sequences, and all apple snails collected in Hong Kong were identified as Pomacea canaliculata. Since its initial introduction in the early 1980s, the distribution of this invasive snail has only expanded slightly. Principal component analysis showed that the environmental characteristics of the study sites varied with habitat. Streams were quite homogenous in chemical characteristics and contained little dissolved minerals, whereas ponds, abandoned wet farmlands and drainage channels all showed great variations in nutrient loading. Discriminant function analysis (DFA) revealed that the inhabited sites typically had high levels of phosphate and alkalinity, but the snail was also occasionally found in streams where dissolved ion concentrations and nutrient levels were low. Most of the inhabitable wetlands in New Territories have already been occupied by P. canaliculata. Because of its unsuitable hydrology, Hong Kong Island remains uninhabited by this species. Lantau Island has habitable sites for this species, and thus is susceptible for invasion in the future.
Field and Lab Studies of Less Charismatic Predators of Florida Apple Snails byPhilip C. Darby1, Sarah E. Kell1,2, Robert Eckert1,3 and Patricia L. Valentine-Darby1, 1Department of Biology, University of West Florida, Pensacola, FL, 2U.S. EPA Gulf Ecology Division, Gulf Breeze, FL, 3New Hampshire Fish and Game, Durham, NH, Greater Everglades Ecosystem Restoration: Planning, Policy and Science Meeting, Naples, FL, 2008
Abstract. The Florida apple snail (Pomacea paludosa, Say) is best known as the nearly exclusive prey of the endangered snail kite (Rostramus sociabilis) and other relatively ‘charismatic’ predators (limpkins, alligators, etc.). These larger predators target the adult sized snails, but juveniles hatch out at 3-4 mm in diameter; consequently snails could be vulnerable to a wide variety of small aquatic predators. We hypothesized that relatively diminutive aquatic vertebrate and invertebrate predators of juvenile apple snails play a significant role in snail population regulation. An assessment of predation rates on juvenile snails by these less charismatic predators is paramount to understanding the demography of this ecologically important snail. We approached our study of juvenile snail predation in three phases. First, we captured potential predators from the field and placed them in tanks to observe whether or not they would eat 3- 15mm diameter apple snails. Second, we conducted a series of lab trials using confirmed snail predators, crayfish (Procambarus allenii) and mud and musk turtles (Kinosternon bauri, Sternotherus odoratus), to quantify predator-prey size relationships. Third, we conducted field trials of predation rates using tethered snails [the tethering approach was validated in controlled laboratory studies]. Snails ranging in size from 4-20 mm were tethered to poles placed in three study sites in WCA2B; each site had 30 tethering stations. We checked each station every three days during two 12-d trials, and we replaced tethered snails that had been preyed upon. We also set traps to collect fish and turtles in order to assess the relative abundance of predators in each of the three sites. We observed the following species (in addition to crayfish and turtles) eat apple snails: Bluegill (Lepomis macrochirus), Redear sunfish (Lepomis microlophus), Mayan cichclid (Cichlosoma urophthalmus), Seminole killifish (Fundulus seminolis), and Greater Siren (Siren lacertina).
Crayfish with carapace lengths of 15 to 35 mm ate snails from 4 to 12 mm in approximate diameter (regression results; R2=0.69 n=12, P=0.0008). Musk and mud turtles with carapace lengths 35-95 mm ate snails from 8-22 mm in diameter (R2=0.77, n=18, P=0.0008). In the field trials, predation rates averaged 8% per day per across all sites and snail size ranges. There was generally lower predation in sites with relatively fewer captured predators (statistical analyses to be completed).
Our data clearly indicate that small ‘less charismatic’ predators like crayfish and small turtles prey on juvenile apple snails. The field study indicated that aquatic predators consume a significant proportion of available juvenile snails. Any potential bias in using the tethering approach will be discussed, and additional detailed analyses will be presented.
• We documented several previously unidentified predators of juvenile apple snails
• Snail sizes consumed were a direct function of predator size, such that predation occurred on all size snails from hatchling to adult.
• Quantifying predation rates is critical to understanding what regulates populations of Florida apple snails, a species considered a barometer of Greater Everglades ecosystem health.
Out of South America: multiple origins of non-native apple snails in Asia by K. A. Hayes, R. C. Joshi, S. C. Thiengo, and R. H. Cowie, Center for Conservation Research and Training, Pacific Biosciences Research Center, University of Hawaii, 3050 Maile Way, Gilmore 408, Honolulu, Hawaii 96822, USA, May 2008
Abstract. Apple snails (Ampullariidae: Pomacea) native to the New World have become agricultural and environmental pests widely in southern and eastern Asia since their introduction in about 1980. Although their impacts have been extensively documented, considerable confusion persists regarding their identities and geographical origins. Efforts to resolve the confusion have suffered from inadequate taxonomic and geographical sampling from both native and introduced ranges. Using phylogenetic and genealogical methods, we analysed 610–655 bp of cytochrome c oxidase subunit I DNA sequences from 783 apple snails from 164 Asian locations and 57 native South American locations. In Asia, we found four species of Pomacea in two clades: (1) Pomacea canaliculata and P. insularum, and (2) P. scalaris and P. diffusa. Parsimony networks and mismatch distributions indicate that the non-native ranges of the two most widespread species, P. canaliculata and P. insularum, probably result from multiple introductions. Molecular analyses are consistent with early accounts; non-native P. canaliculata populations trace back to multiple locations in Argentina and have probably been introduced more than once. In contrast, P. insularum was probably introduced from Brazil and Argentina independently. Multiple introductions may, in part, explain the success and rapid spread of these two species. Unlike P. canaliculata and P. insularum, P. scalaris and P. diffusa were probably introduced through the aquarium trade, derived originally from Argentina and Brazil, respectively. Possible physiological, ecological, and native range differences among these four species highlight the importance of accurate identification in understanding invasion patterns and processes, which is vital in developing and implementing management strategies.
Wetland Restoration and Invasive Species: Apple snail (Pomacea insularum) Feeding on Native and Invasive Aquatic Plants by Lyubov E. Burlakova, Alexander Y. Karatayev, Dianna K. Padilla, Leah D. Cartwright, David N. Hollas, May 2008
Abstract. The apple snail Pomacea insularum is an aquatic invasive gastropod native to South America that has the potential to cause harm to aquatic ecosystems, wetland restoration, and agriculture. To predict the potential impact of this snail on aquatic ecosystems, we tested the feeding rate of P. insularum, under laboratory nonchoice experiments, for 3 species of invasive macrophytes and 13 species of native aquatic plants that are important for wetland restoration and health. High levels of consumption were recorded for four native species (Ceratophyllum demersum, Hymenocallis liriosme, Ruppia maritima, and Sagittaria lancifolia) and three invasive species (Colocasia esculenta, Alternanthera philoxeroides, and Eichhornia crassipes). In contrast, less than 10% of the biomass of Spartina alterniflora, Scirpus californicus, Thalia dealbata, and Typha latifolia was consumed by P. insularum over the test period. The palatability of macrophytes was negatively correlated with dry matter content, making our results generalizable to all regions where this invader may be present. Based on our results, wetland restoration in areas invaded by P. insularum should focus on emergent structural species with low palatability. Apple snails should not be considered as agents of biocontrol for invasive plants; although apple snails fed on invasive plants at a high rate, their consumption of many native species was even greater.
Shell morphology and physiological tolerances of the exotic apple snails Pomacea insularum and Pomacea canaliculata, in Florida by Jennifer L. Bernatis, UF – Fisheries and Aquatic Sciences, University of Florida and Florida Fish and Wildlife Commission, 7922 NW 71st St, Gainesville, FL 32653, May 2008
Abstract. The South American apple snails Pomacea canaliculata and Pomacea insularum have been implicated in the alteration of Florida aquatic ecosystems. However, the invasive Pomacea species truly responsible for the damage is unknown; recent genetic work demonstrated inaccuracies in the original species identifications. The purpose of this research was twofold: 1) determine differences in shell morphology between the species and, 2) determine physiological tolerances to environmental stressors. An analysis of 45 shell dimension relationships showed significant differences: adults (35 of 45 pairs, P < 0.05), and juveniles (33 of 45 pairs, P 100 patients. A 2006 outbreak in Beijing infected 131 persons. Based on the biologic characteristics of P. canaliculata, blocking its life cycle is one of the most effective methods to limit the outbreak of angiostrongyliasis. However, the current widespread distribution of P. canaliculata in China and the lack of a highly effective control method make the disease extremely difficult to eliminate. More outbreaks associated with ingestion of this snail will likely occur if food safety rules are not strictly enforced. Citizens must also be educated to avoid eating raw, undercooked snail meat or raw vegetables from regions that may be contaminated with infective mucous trails deposited by these snails.
Efficacy of quinoa (Chenopodium quinoa) saponins against golden apple snail (Pomacea canaliculata) in the Philippines under laboratory conditions by Ravindra C. Joshia, , , Ricardo San Martínb, , , Cesar Saez-Navarreteb, John Alarconb, Javier Sainzb, Mina M. Antolina, Antonio R. Martina and Leocadio S. Sebastiana, aDepartment of Agriculture, Philippine Research Institute (DA-PhilRice), bDepartment of Chemical and Bioprocess Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile, Crop Protection, Volume 27, Issues 3-5, May 2008
Abstract. A novel product for managing Pomacea canaliculata, golden apple snail (GAS), containing quinoa saponins (Chenopodium quinoa), was evaluated under laboratory conditions for the protection of newly sprouted rice seeds. Experimental methods mimicked conditions found in direct-seeded rice cultivation in the Philippines, but with a very high GAS density (90 snails/m2). Protection of newly sprouted seeds was directly proportional to saponin concentration in rice water. At 9 and 11 ppm saponin, seedling protection after 48 h against GAS of different sizes was 93% and 95%, respectively. Seedling recovery after 5 d with 11 ppm saponin was 93%. This value declined to 0% and 4%, for the control (untreated) and niclosamide, a synthetic chemical molluscicide, respectively. The results indicated that although niclosamide provides high efficacy against GAS (100% mortality, 24 h), it has a serious detrimental effect on rice seedlings. Mean GAS mortality with 11 ppm saponin was low at 24 h (45%), but increased to 94% at 48 h. Thus, seedling protection was probably due to an almost immediate closure of the snail’s opercula when exposed to saponin solutions, followed by significant death rates within 24 and 48 h. The product also exhibits ovicidal effects, particularly with 1–5 d old egg masses; older egg masses were less susceptible to the product. The use of 11 ppm saponin slightly affected shoot growth, but this effect disappeared with time and the plants attained normal development. Saponin application rates at 10 ppm saponin in the rice water correspond to ca. 6 kg product/ha under cultivation conditions used in the Philippines. These results suggest that quinoa saponins may represent a commercially feasible environmentally benign alternative to synthetic chemical molluscicides against GAS, particularly in direct-seeded rice culture.
Emerging Angiostrongyliasis in Mainland China by Shan Lv,* Yi Zhang,* Peter Steinmann,† and Xiao-Nong Zhou *, *Chinese Center for Disease Control and Prevention, Shanghai, People’s Republic of China,†Swiss Tropical Institute, Basel, Switzerland, Emerging Infectious Diseases, 14(1): 161-164, January 2008
Abstract. Angiostrongylus cantonensis was first described as a parasite of the Norway rat (Rattus norvegicus) and the black rat (R. rattus) in Guangzhou (formerly Canton), People’s Republic of China, in 1933. The first human case was reported from Taiwan in 1945. Transmission to humans is primarily by consumption of raw snails. Contaminated vegetables and paratenic hosts such as freshwater prawns, crabs, and frogs may also play a role in transmission (1).
The first case of human angiostrongyliasis in mainland China was diagnosed in 1984 (2). During the past decade, the number of cases has sharply increased (3). A large outbreak occurred in Beijing during 2006. The outbreak peaked during August and involved 160 persons, 100 of whom were hospitalized. This number of patients is similar to the total number of infections recorded in China over the past decade. Our aim was to briefly review angiostrongyliasis outbreaks in mainland China, update angiostrongyliasis epidemiology, and recommend measures to prevent and control angiostrongyliasis.
Dry down impacts on apple snail (Pomacea paludosa) demography: implications for wetland water management by Philip C. Darby1, Robert E. Bennetts2,3, H. Franklin Percival4 ,1Department of Biology, University of West Florida, Pensacola, FL, ,2U.S. Geological Survey, Gainesville, FL, 3National Park Service, New Mexico Highlands University, Las Vegas, New Mexico, 4Florida Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, University of Florida, Gainesville, FL, Wetlands 28(1):204-214. 2008
Abstract. Florida apple snails (Pomacea paludosa Say) are prey for several wetland-dependent predators, most notably for the endangered Florida snail kite (Rostrhamus sociabilis Vieillot). Management concerns for kites have been raised regarding the impacts of wetland dry downs on snails, but little data exists to validate these concerns. We simulated drying events in experimental tanks, where we observed that snail survival patterns, regardless of hydrology, were driven by a post-reproductive die off. In contrast to earlier reports of little to no dry down tolerance, we found that 70% of pre-reproductive adult-sized snails survived a 12-week dry down. Smaller size classes of snails exhibited significantly lower survival rates (< 50% after eight weeks dry). Field surveys showed that 77% of egg production occurs in April–June. Our hydrologic analyses of six peninsular Florida wetlands showed that most dry downs overlapped a portion of the peak snail breeding season, and 70% of dry downs were ≤ 12 weeks in duration. Dry down timing can affect recruitment by truncating annual egg production and stranding juveniles. Dry down survival rates and seasonal patterns of egg cluster production helped define a range of hydrologic conditions that support robust apple snail populations, and illustrate why multiple characteristics of dry down events should be considered in developing target hydrologic regimes for wetland fauna.
Juvenile snails, adult appetites: contrasting resource consumption between two species of applesnails (Pomacea) by Brandon B. Boland1, Mariana Meerhoff2,3, Claudia Fosalba2, Néstor Mazzeo2, Matthew A. Barnes1,4 and Romi L. Burks1, 1Department of Biology, Southwestern University, 1001 E. University Avenue, Georgetown, TX 78626, USA; 2Departamento de Ecología, Facultad de Ciencias, Universidad de la República, Iguá 4225 CP, 11300 Montevideo, Uruguay; 3Department of Freshwater Ecology, National Environmental Research Institute, University of Aarhus Vejlsøvej 25, 8600 Silkeborg, Denmark; and 4Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA, Journal of Molluscan Studies 74(1):47-54, 2008
Abstract. Research on aquatic snails usually examines consumption of periphyton,but emergence of large, invasive aquatic snails that prefermacrophytes has necessitated a new understanding about snailherbivory. Ample research exists detailing invasive potentialof certain species of applesnails, such as Pomacea canaliculata,to successfully invade aquatic ecosystems. However, very fewstudies examine differences in resource utilization betweendifferent size-classes within species, or between closely-relatedspecies. To quantify these potential differences, we comparedper mass resource consumption at two life history stages byP. canaliculata and a lesser-known species recently identifiedin Texas (USA), Pomacea insularum. We presented adult and juvenilesnails with whole and reconstituted forms of Lactuca sativalongifolia (romaine lettuce), Myriophyllum spp. (watermilfoil),and Eichhornia crassipes (water hyacinth). In addition, we addedchemical extracts to reconstituted watermilfoil and water hyacinthto test if extracts deterred consumption. Addition of periphytonto reconstituted watermilfoil allowed us to examine supplementarystructure and chemistry. Juveniles seemed to prefer reconstitutedresources. All snails, regardless of life-history stage, avoidedwater hyacinth in either form. Chemical extracts from both waterhyacinth and watermilfoil deterred consumption by all snails.When presented with reconstituted watermilfoil containing additionalperiphyton, juvenile P. insularum consumed more resource withadditional periphyton. In contrast, periphyton presence didnot produce a noticeable effect on P. canaliculata consumption.Overall, juveniles of both species consumed considerably moreby mass than their respective adult counterparts. Through increasednumbers and difficult detection, juvenile applesnails couldfeasibly consume a greater proportion of plant biomass thanadult applesnails and this may partially underlie the successof global applesnail invasions.
Influence of Copper on the Feeding Rate, Growth and Reproduction of the Golden Apple Snail, Pomacea canaliculata Lamarck by Silvia C. Peña1 and Glorina N. Pocsidio2 Institute of Environmental Science and Meteorology, University of the Philippines, Diliman, Quezon City, 1101, Philippine, Bulletin of Environmental Contamination and Toxicology, Volume 79, Number 6 / December, 2007
Abstract. The influence of copper on feeding rate, growth, and reproduction of Pomacea canaliculata Lamarck was evaluated. Ten days of exposure to copper of relatively high concentration (67.5 μg/L) reduced the snails’ feeding rate and retarded their growth. Exposure to 20 μg/L after 36 days increased feeding rate to 28%. After 20 days of exposure at 30 μg/L, snail’s growth was significant but thereafter declined. Growth of all snails including control was negligible by day 50 when snails were in the reproductive state. Copper did not affect reproduction.
Ultra-estrutura radular dos Ampullariidae sul-americanos (Gastropoda: Prosobranchia) by Martín, SM., Negrete, LHL., IInvestigador Adjunto Comisión de Investigaciones Científicas de la provincia de Buenos Aires – CIC, Div. Zoología Invertebrados, Facultad Ciencias Naturales y Museo La Plata – FCNYM, Universidad Nacional de La Plata, Buenos Aires, Argentina – UNLP, IIDiv. Zoología Invertebrados, FCNYM, Universidad Nacional de La Plata, Buenos Aires, Argentina – UNLP Paseo del Bosque S/N. La Plata (1900).Bs.As. Argentina Braz. J. Biol. vol.67 no.4 São Carlos (Nov. 2007)
Abstract. The radula of five species of South American Ampullariidae was analysed by Scanning Electron Microscope (SEM) with the purpose of enlarging new studies on the systematic of this family. The studied species were Pomacea -canaliculata (Lamarck, 1822), Pomacea scalaris (d’Orbigny, 1835), Pomella (P.) megastoma (Gray, 1847), Asolene (A.) platae (Maton, 1809) and Felipponea neritiniformis (Dall, 1919). The central tooth shows different attributes which provide the means for generic determination; the analysis of the central tooth, the lateral and marginal ones by SEM adds further information for species differentiation. (Includes excellent micrograph of the radula of Pomacea canaliculata)
Comparing applesnails with oranges: the need to standardize measuring techniques when studying Pomacea by Abigail K. Youens and Romi L. Burks, Southwestern University,Georgetown, TX 78626, USA, Aquatic Ecology, Springer Science & Business Media B.V. (August 2007)
Abstract. Although invaders come in all shapes and sizes, several mollusks have recently achieved notoriety as both economically and ecologically costly invaders. Applesnails of the genus Pomacea get their name from reaching the size of an apple. Native to South America, the species P. insularum has recently established reproducing, and potentially invasive, populations in Texas, Alabama, Georgia, and Florida. In contrast to the widely invasive golden applesnail (P. canaliculata), few studies of the channeled species P. insularum exist. In studying similar invasive applesnail species, scientists use several methods of measurement. We have explored the relationships among shell height, operculum width, and weight among juvenile and adult P. insularum and tested their inter-measurer reliability. We also investigated the use of shell height, shell length, and operculum width measurements in P. canaliculata studies and observed whether or not those studies defined their measurements. We found that operculum width served as a significantly more reliable measure among researchers. Furthermore, operculum width better predicted weight than shell height. The majority of articles that measured P. canaliculata did not define their measurements, which may cause problems when comparing studies between native and exotic populations or when comparing the two species. We recommend that future studies of P. insularum use operculum width to measure snails and explore a possible sex dimorphism in the operculum width of adult P. insularum.
A water-borne sex pheromone and trail following in the apple snail, Pomacea canaliculata by Mari Takeichi, Yoshio Hirai and Yoichi Yusa (July 2007)
Abstract. We investigated whether individuals of the apple snail Pomacea canaliculata were attracted by conspecifics or follow mucus trails of other individuals. The snails’ behaviour was studied by a series of choice experiments in a T-maze and in Petri dishes. Both males and females chose the side with a snail of the opposite sex significantly more frequently than the control side without a snail. Males were attracted by water conditioned with females more frequently than unconditioned water, whereas females did not show a preference for male-conditioned water. Moreover, juveniles were not attracted by water conditioned with a male, a female and a juvenile. These data indicate that males were attracted by female odour, which contains one or more water-borne sex pheromones. In addition, both males and females follow mucus trails of snails of the opposite sex. Since females also followed trails of females, the function of trail following is not necessarily related to reproduction. In these experiments P. canaliculata did not distinguish the direction of the trail.
The identity, distribution, and impacts of non-native apple snails in the continental United States by Timothy Rawlings, Kenneth Hayes, Robert Cowie and Timothy Collins (June 2007)
Excerpt. Pomacea insularum and P. canaliculata pose the greatest threat to agriculture and native wetland ecosystems in the U.S. One of the better predictors of the effect of an invasive species is the effect of the species or related species in other areas where it has been introduced . The potential of P. canaliculata has been clearly demonstrated in Southeast Asia where its introduction into a tropical wetland ecosystem in Thailand resulted in dramatic changes in biodiversity and ecosystem functioning , and by its devastating effects on agriculture, especially wetland rice production. Currently, the occurrence of P. canaliculata has been confirmed in California and Arizona in the continental U.S. However, it has the potential to spread into other areas, including the rice-growing parts of California, where it could cause serious damage.
Some of the ecological and agricultural impacts in Asia associated with P. canaliculata are almost certainly attributable to Pomacea insularum. This species is also widespread in the region, K.A. Hayes, R.C. Joshi, S.C. Thiengo, and R.H. Cowie, in prep.; see below], but has not been explicitly acknowledged as a serious pest because of the confusion in identification of these two species, with most of the literature referring to P. canaliculata. Pomacea insularum may therefore be likely to have a significant impact on aquatic ecosystems and pose a threat to crops in the southeastern U.S. , particularly given the potential for it to spread through parts of Alabama, Mississippi, Louisiana and Texas.
The match of introduced haplotypes of P. canaliculata and P. insularum to native Argentinean samples from approximately 35°S suggests that the introduced populations of these species may be cold tolerant and capable of surviving occasional frosts. Moreover, P. canaliculata occurs as far as 38-39°S, and topography rather than climate may set the natural southern limit of this species. The average minimum monthly temperature in Buenos Aires is 4-6 degrees Celsius (39-43 degrees Fahrenheit) from May to September, slightly lower than the average minimum winter monthly temperatures in Charleston, South Carolina. Consequently, P. insularum could potentially spread at least this far north on the Atlantic Coastal Plain, and through parts of Alabama, Mississippi, Louisiana, and Texas on the Gulf Coastal Plain. Similarly, P. canaliculata may be able to spread from its current introduced locations in California at least as far north as San Francisco. Ecological niche modeling based on the native and introduced range of these species will permit a more refined estimate of potential introduced ranges. An important caveat here is that reports of the native ranges of these two species may be commingled.
Salinity, Ph, Temperature, Desiccation And Hypoxia Tolerance In The Invasive Freshwater Apple Snail Pomacea Insularum by Ramakrishnan, Veena (May 2007)
Abstract. Pomacea insularum is a tropical and subtropical, ampullariid, freshwater prosobranch snail that is native to slow -flowing rivers and canals in South America. It is a member of the genus, Pomacea , and , like other species in this genus , can be a severe agricultural pest in wetland rice and taro agriculture systems . It has been introduced to the United States, establishing populations in the rice belt region of southeastern Texas. The resistance adaptations of P. insularum were investigated with respect to important physico -chemical parameters including temperature , salinity , pH , emersion , desiccation and progressive hypoxia in order to predict its potential distribution in North America , evaluate its threat to U .S. rice and taro crops and to develop environmentally acceptable non -chemical control and management strategies to prevent its further dispersal in North America . The research results indicated that the main factor likely to limit the macrogeographic distribution of P. insularum in North America was temperature based on its incipient tolerated temperature range of 15 .2° -36 .6°C . Its 15°C lower lethal limit will restrict its distribution to southern and western coastal regions and Florida in the United States. The tolerances of P. insularum to salinity, pH , emersion , desiccation and hypoxia elucidated in this study can be utilized to develop a risk assessment for this species’ microgeographic distribution . Its tolerated salinity range was 0 -6 .8 which should prevent it from deeply invading estuarine habitats. Its tolerated pH range is 4 .0 -10 .5, which spans that of most freshwater invertebrate and fish species. Its incipient emersion tolerance ranged from 70 days at 30°C and >95 % relative humidity (RH) to >308 days at 20° -25°C and 75 % – >95 % RH . Its maximum desiccation tolerance was loss of 58 % of total corporal plus extracorporal water. It was a moderate regulator of oxygen consumption when subjected to progressive hypoxia, maintaining a normal oxygen uptake rate down to a critical Po2 of 80 -120 Torr depending on temperature. These results indicated that, within its tolerated temperature range, P . insularum, will be most successful in oxygenated , flowing-water habitats and could be controlled by periodic dewatering of natural or wetland aquatic habitats.
The development of animal attractants for apple snail (Pomacea canaliculata) by Fu-ju Chuang, Master’s Thesis, Graduate Institute of Life Science, National Kaohsiung Normal University, Kaohsiung,Taiwan, 2007
Abstract. The apple snail, Pomacea canaliculata has made a tremendous threat to agricultural crops as well as environmental ecology in Taiwan. Although various control methods are available, there are certain limitations in each of the applications. The present study was conducted to evaluate the application potential of food preference in attractant usage to apple snails. It has been found that apple snails actively searched animal materials. Fish blood and egg glair were as attractive as banana (Musa sp.). With equal weight, blood clots from cobia (Rachycentron canadum) and pig (Sus sp.) were more attractive than banana, and cooked pig blood was as attractive as banana. The response of snails to concentrated extracts from fish blood (with molecular we ight > 5000) was stronger than banana. There were no significant differences in snails’ responses to blood from pig, cobia, freshwater and seawater milk fish (Chanos chanos). Furthermore, protein was probably the attractive source to apple snails and frozen-treated blood increased attractive response. As expected, blood clots from cobia and pig were more attractive than banana in the field. In summary, the results show that animal protein is potentially applicable as attractive components for apple snails.
Seasonal Changes In Cold Hardiness Of The Invasive Freshwater Apple Snail, Pomacea canaliculata (Lamarck) (Gastropoda: Ampullariidae) byTakashi Wada* and Keiichiro Matsukura National Agricultural Research Center for Kyushu Okinawa Region, Suya 2421, Koshi, Kumamoto 861-1192, Japan, Malacologia 49(2):383-392. (2007)
Abstract. We investigated the cold hardiness of a South American freshwater apple snail, Pomacea canaliculata, which began to invade Japanese paddy fields in the early 1980s. Pomacea canaliculata exhibited apparent seasonal fluctuation in its cold hardiness. Snails collected from submerged paddy fields in summer were less tolerant to cold, and none survived exposure to 0°C for five days. With decreasing temperature, together with drainage of its habitat in autumn, P. canaliculata developed cold hardiness, attaining almost 100% survivorship after exposure to 0°C for five days in December. The snails resting in drained fields were approximately nine times more cold tolerant than those collected from submerged fields, based on the time to 50% mortality at 0°C. Snails overwintering in aquatic conditions also acquired cold hardiness.
Fecundity as a Basis for Risk Assessment of Nonindigenous Freshwater Molluscs by REUBEN P. KELLER1,*,JOHN M. DRAKE1,*, and DAVID M. LODGE2,* Conservation Biology, 21: 191–200. (February 2007)
Abstract.The most efficient way toreduce future damages from nonindigenous species is to prevent the introduction of harmful species. Although ecologists have long sought to predict the identity of such species, recent methodological advances promise success where previous attempts failed. We applied recently developed risk assessment approaches to nonindigenous freshwater molluscs at two geographic scales: the Laurentian Great Lakes basin and the 48 contiguous states of the United States. We used data on natural history and biogeography to discriminate between
established freshwater molluscs that are benign and those that constitute
nuisances (i.e., cause environmental and/or economic damage). Two statistical
techniques, logistic regression and categorical tree analysis, showed that
nuisance status was positively associated with fecundity. Other aspects of
natural history and biogeography did not significantly affect likelihood of
becoming a nuisance. We then used the derived statistical models to predict the
chance that 15 mollusc species not yet in natural ecosystems would cause damage
if they become established. We also tested whether time since establishment is
related to the likelihood that nonindigenous mollusc species in the Great Lakes
and United States would cause negative impacts. No significant relationship was
evident at the U.S. scale, but recently established molluscs within the Great
Lakes were more likely to cause negative impacts. This may reflect changing
environmental conditions, changing patterns of trade, or may be an indication
of “invasional meltdown.” Our quantitative analyses could be extended to other
taxa and ecosystems and offer a number of improvements over the qualitative
risk assessments currently used by U.S. (and other) government agencies.
The effect of temperature on the development of Angiostrongylus cantonensis in Pomacea canaliculataby S. Lv, X. N. Zhou,Y. I. Zhang et al.,Parasitology Research, vol. 99, no. 5, pp. 583–587, 2006
Abstract. Angiostrongyliasis cantonensis, clinically presented as eosinophilic meningitis, is a snail-borne parasitic disease. We studied the effects of different temperatures on the larval development of Angiostrongylus cantonensis in the freshwater snail Pomacea canaliculata. Six groups of snails were infected and each
group was cultured under different temperature conditions. At predefined intervals, four snails from each group were dissected to examine the larval development. The development–time curve of each group was drawn according to the fraction of third-stage larvae present. The developmental time was defined as the time needed until 50% of the first-stage larvae developed into third-stage larvae. A linear regression model was established based on the time (D; in days) and the corresponding temperature (T; in degrees Celsius). The threshold temperature for larval development was 15.04°C and the thermal constant was 262.53
degree-days. These parameters could be helpful in estimating the number of parasite generations in a year and the impact of climate change on the distribution of A. cantonensis.
THE EFFECTS OF WETLAND HABITAT STRUCTURE ON FLORIDA APPLE SNAIL DENSITY by Laksiri B. Karunaratne & Philip C. Darby, Department of Biology, University of West Florida, Pensacola, Florida, and Robert E. Bennetts, U.S. Geological Survey, Gainesville, Florida in Wetlands, Vol. 26, Issue 4, pp. 1143-1150 (December 2006)
Abstract. Wetlands often support a variety of juxtaposed habitat patches (e.g., grass-, shrub- or tree-dominated) differentially suited to support the inhabiting fauna. The proportion of available habitat types has been affected by human activity and consequently has contributed to degrading habitat quality for some species. The Florida apple snail (Pomacea paludosa) has drawn attention as a critical prey item for wetlands wildlife and as an indicator of wetlands restoration success in peninsular Florida, USA. An apparent contradiction has evolved wherein this species appears intolerant of drying events, but these disturbances may be necessary to maintain suitable habitat structure for apple snails. We recently reported that assertions regarding intolerance to dry downs in this species were inaccurate. Here, we compared snail density in habitats with (wet prairie) and without (slough) emergent macrophytes, as well as evaluating the effects of structural attributes within the broad wet prairie habitat type. Snail densities were greater in prairies relative to sloughs (χ2 = 12.90, df = 1, P = 0.0003), often by a factor of two to three. Within wet prairie habitats, we found greater snail densities in Panicum hemitomon as compared to Eleocharis cellulosa (χ2 = 31.45, df = 1, P = 0.0001). Significantly fewer snails were found in dense E. cellulosa as compared to habitats with lower stem density (χ2 = 10.73, df = 1, P = 0.011). Our results indicate that wet prairie habitat supports greater snail densities than Nymphaea-dominated slough. Our results have implications for wetlands water management in that continuous inundation has been shown to convert wet prairie to slough habitat, and we suggest this should be avoided in support of apple snails and their predators.
Channeled-type applesnails: Current distribution, densities and potential threat to natural ecosystems and agriculture by Burlakova, LE, Karatayev, AY, Hollas, DN, and Cartwright, LD, Journal of Shellfish Research [J. Shellfish Res.]. Vol. 25, no. 2, p. 716. Aug 2006.
The aquatic invasive gastropod Pomacea canaliculata (channeled apple snail), originally from South America, has become a major pest of rice crops throughout the Indo-Pacific Region. These large herbivorous snails can reach maturity in about two months during the summer, reproduce several times a month, and aestivate for several months, burying into the soil if the habitat dries out. By mid 2005, living populations of channeled-type apple snails were reported from Florida, Texas, California, Alabama, Arizona, and Georgia. According to the results of genetic analyses, specimens from Texas and Florida belong to the P. canaliculata-group. The first reproductive apple snail population in Texas was reported in 1989, and by the summer of 2005 snails were found in six southeastern counties (Harris, Chambers, Brazoria, Galveston, Fort Bend, and Waller). Reproduction of channeled-type apple snails in Texas continues for at least 8 months, from March to the beginning of November. Densities of snails in Texas vary depending on waterbody type and possibly presence of predators. The rice growing technology used in Texas combined with current low densities of snails are the likely reasons why agricultural damage due to apple snails has not yet been detected.
That’s the way the egg hatches: Determining patterns in egg size, clutch variability, and hatchling emergence in an exotic versus native population of applesnails by M.A. Barnes1, B.B. Boland1, M. Meerhoff2, C. Fosalba2, N. Mazzeo2, and R.L. Burks1.1Department of Biology, Southwestern University, Georgetown, TX 78626, 2Departamento de Ecología, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay, Poster Presented at the NABS Annual meeting, Anchorage, Alaska, 2006
Abstract. Establishment of a reproductively viable population announces invasion success. Although cryptic as adults, the appearance of bright pink egg clutches provides the first undeniable sign of the presence of applesnails (Pomacea). Our study compares and contrasts egg and hatchling life history stages between an exotic (Texas) and a native (Uruguay) population of Pomacea. Exotic Pomacea deposit eggs on any hard surface. Uruguayan Pomacea preferentially deposited eggs on Schoenoplectus californicus near the shoreline. Native Pomacea laid fewer eggs per clutch than exotic populations. Furthermore, a much stronger relationship between clutch mass and egg number (R2 = 0.88 ) existed in Uruguay, suggesting higher clutch size variability in the exotic population. Most eggs from Uruguay hatched successfully, while Texas clutch hatching efficiency varied more considerably. For Texas snails, we did not find any relationship between hatching date and hatchling size, instead clearly determining a threshold hatching size of 1.1 mm (study on-going for native population). However, we found that eggs deposited over fish-cued water could exhibit significantly delayed hatching times. Similar-sized hatchlings also exhibit different growth patterns when presented with fish cues or grown in salt water. Overall, our work may lend insight into how reproduction and early survival facilitates invasion success.
Understanding the golden apple snail (Pomacea canaliculata): biology and early initiatives to control the pest in the Philippines by C. B. Adalla and E. A. Magsino. In Global advances in ecology and management of golden apple snails, Joshi, R. C., Sebastian, L. S. (Ed.) 2006
Abstract. The golden apple snail is seen as a major pest of rice in the Philippines and in much of Asia. Its voracious appetite and high reproduction rate combine to make this species a bane of irrigated rice farmers. There are at least 3 species of Pomacea in the country, introduced in different parts of the archipelago in the early 1980s with the idea of creating an escargot industry and improving farmers’ income. Similar to what happened in Japan, Taiwan, and Hawaii, local consumers did not take to the taste of Pomacea, and so the industry’s economic potential evaporated. One estimate of the economic loss in the Philippines due to the golden snail reached at least $US 1 billion in 1990. The “snail invasion” is continuing, but up-to-date, adequate, and accurate statistics about the species and the pest situation are unavailable and should be generated, as the available information is inadequate and only up to 2000 at the latest. There should be a few major or continuing studies on how the pest can be controlled effectively. While integrated pest management is recommended, the technological components of the package remain to be generated and verified in the field.
Genetic Characterization of Invasive Apple Snail Populations: Evidence of Multiple Introductions to SE Asia by K. A. Hayes, University of Hawaii-Manoa, 72nd Annual American Malacological Society, University of Washington, Seattle, WA, 29 July-3 August, 2006
Abstract. The freshwater apple snail genus Pomacea (family Ampullariidae) has a native range covering most of South and Central America and the southeastern United States. Pomacea have been introduced widely throughout southern and eastern Asia, Hawaii, many Pacific islands, and elsewhere in the mainland U.S. In their introduced ranges they have become major pests of wetland crops, notably rice and taro. The taxonomy of Pomacea, including the identity and precise geographic origins of invasive populations, is poorly understood. This lack of understanding has implications for research on many aspects of ampullariid biology, as well as the development of effective pest management programs. Apple snails have been sampled from more than 200 locations throughout their introduced and native ranges. Phylogenetic analyses of 1000 mitochondrial COI sequences representing 24 Pomacea species suggest that at least 4 Pomacea species have been introduced into southern and eastern Asia from multiple geographic origins in South America. This is contrary to anecdotal accounts of a single introduction of P. canaliculata followed by range expansion throughout the region. Argentina is clearly the source of the most widespread invasives, P. canaliculata and P. insularum, as well as the less common P. scalaris. Pomacea diffusa (previously thought to be P. bridgesii) likely originated in the Amazon region of Brazil. Clarification of systematic relationships and geographic origins of apple snails should prove valuable in developing management strategies by linking accurate species identities to ecological information and life history factors that control the distribution and abundance of these species.
Heavy Predation on Freshwater Bryozoans by the Golden Apple Snail, Pomacea canaliculata by Timothy S. Wood, Patana Anurakpongsatorn, Ratcha Chaichana, and Tunlawit Sarapanajaru (May 2006)
Abstract. Laboratory feeding observations confirm that the golden apple snail (Pomacea canaliculata Lamarck, 1822) is a voracious predator of phylactolaemate bryozoans. An invasive species in Southeast Asia since the early 1980s, the snail now occupies most freshwater ponds, lakes, and rivers throughout the region. Despite the absence of baseline data, it appears that the snail has had a profound effect on the freshwater bryozoan community, including both tubular and globular colonies. The common gymnolaemate, Hislopia, is less affected. From repeated feeding trials it appears that indigenous apple snails (Pila spp.) do not graze on bryozoans; nor does the large indigenous Cipangopaludina chinensis.
Size-dependent effects of an invasive herbivorous snail (Pomacea canaliculata) on macrophytes and periphyton in Asian wetlands by CARLSSON, NILS O. L.; BRÖNMARK, CHRISTER, Freshwater Biology, Volume 51, Number 4, (April 2006)
1. The invasive golden apple snail (Pomacea canaliculata), native to South America, is a serious pest on rice seedlings in south-east Asia and has also been shown to consume large amounts of macrophytes in natural wetlands, with large effects on ecosystem functioning. Earlier studies suggest that the snail undergoes an ontogenetic diet shift, feeding on algae and detritus as juveniles and shifting to aquatic macrophytes as adults.
2. Here, we study the effects of snail populations with a size-structure typical of either populations at an invasive front or the size-structure of established populations. In an enclosure experiment performed in a wetland in Laos, we compared treatments with small snails only (3 mm; invasive treatment) to treatments with small, medium sized (10 mm) and adult (>25 mm) snails (established treatment). The effects of snail grazing on three aquatic macrophyte species and periphytic algae were quantified.
3. We found that snails of all sizes had a strong negative effect on the biomass of all macrophyte species and periphytic algae. There was no evidence of an ontogenetic diet change, i.e. snails in both the invasive and established treatments affected macrophyte biomass. Foraging was size-dependent in that small snails had higher relative foraging capacity (g plant consumed per g of snail) compared with medium and adult snails. Small snails, therefore, depressed growth of medium snails at increasing densities through exploitative competition for preferred resources, while adult snails did not grow at all in the presence of small snails.
4. Density dependence is common in freshwater invertebrates, including gastropod populations, but differences in size dependent foraging- and competitive-ability have rarely been demonstrated in this group of organisms. Knowledge about intra-specific differences in ecological performance may, however, both deepen our understanding of the processes that underlie population dynamics in invertebrates such as gastropods, and help develop control strategies for invasive golden apple snails.
Fossil record of Pomacea (Caenogastropoda: Ampullariidae) in Argentina and its paleoenvironmental implications by Pablo R. Martín* and Claudio G. de Francesco**,* Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, 8000 Bahía Blanca, Argentina, ** Centro de Geología de Costas y del Cuaternario, Universidad Nacional de Mar del Plata, CC. 722, 7600 Mar del Plata, Argentina, Biocell(Mendoza) v.30 n.2 Mendoza mayo/ago. 2006
Exerpts. In many aspects Pomacea canaliculata (Lamarck, 1822) is the best known native snail from Argentina, a fact that has been enhanced since its establishment as a serious rice plague in Asian rice fields (Estebenet et al ., 2006). Notwithstanding, from a paleontological viewpoint, the knowledge of this species is far from being sound and integrated. Compared to more tropical ampullariids, P. canaliculata shows lower tolerance to high temperatures and higher tolerance to low and even freezing temperatures (Cowie, 2002). Although its distribution is basically tropical and subtropical, P. canaliculata is the ampullariid naturally ranging to southernmost latitudes and some populations have been detected in the Southern slope of Ventania and Tandilia Mountains in Buenos Aires Province (e.g. Cazzaniga, 1987a; Estebenet and Cazzaniga, 1998). Berthold (1991) suggested that climate, specially the combination of the 10ºC isotherm and the 600 meter contour line, sets the limits of the distribution of ampullariids worldwide. However, the combination of paleontological and distributional data suggests an alternative hypothesis on the factors actually limiting the southward distribution of P. canaliculata in this region. P. canaliculata never naturally expanded south of the Ventania and Tandilia Mountains , suggesting that this hydrological discontinuity has been the barrier impeding the southward spread of P. canaliculata. The lack of fossil evidence of P. canaliculata on the Southern slope also suggests that present populations found there are the results of anthropogenic dispersal, probably due to fish sowing or as fishing bait (Martín et al., 2001).
Apple snails as disease vectors by Hollingsworth, R.G. and R.H. Cowie. In R. C. Joshi & L. S. Sebastian, Eds. Global Advances in Ecology and Management of Golden Apple Snails. Nueva Ecija: Philippine Rice Research Institute. pp 121-132. (2006)
Abstract. Apple snails (Ampullariidae) are intermediate hosts of parasites causing at least three diseases in humans: cercarial dermatitis (“swimmer’s itch”) caused by trematode cercaria, intestinal problems caused by flukes in the genus Echinostoma, and eosinophilic meningitis caused by the nematode Angiostrongylus cantonensis. Angiostrongyliasis is the most important of these diseases. Experiments show that apple snails do not acquire A. cantonensis as easily as certain other molluscs, and the natural parasite load of individual apple snails is generally much lower than in large species of land molluscs, such as the giant African snail (Achatina fulica) and veronicellid slugs. Nevertheless, apple snails are important carriers of A. cantonensis because of their widespread use as a human food resource and high intra-specific variation in parasite load. Angiostrongyliasis caused by apple snails results primarily from consumption of raw or undercooked snail meat but contact with the debris associated with preparation of the snails for eating may also cause infection. As pest species of apple snails continue to be spread there is the potential for the concomitant spread of A. cantonensis into new regions, increasing the number of cases of angiostrongyliasis worldwide.
Angiostrongrylus cantonensis as a cause of cerebrospinal disease in a yellow-tailed black cockatoo (Calyptorhynchus funereus) and two tawny frogmouths (Podargus strigoides) by Monks, DJ, Carlisle, MS, Carrigan, M, Rose, K, Spratt, D, Gallagher, A, Prociv, P; The University of Queensland, Journal of Avian Medicine and Surgery, Volume 19, Issue 4 (December 2005)
Abstract. A captive yellow-tailed black cockatoo (Calyptorhynchus funereus) and 2 free-living tawny frogmouths (Podargus strigoides), both native Australian species, were presented with neurologic signs including depression and pelvic limb paresis and paralysis. Despite supportive treatment, all 3 birds died or were euthanatized. On histologic examination, sections of metastrongyloid nematode larvae were found in the central nervous system of all 3 birds, whereas intact larvae, identified as Angiostrongylus cantonensis, were recovered from the brain and spinal cord of 2 birds. Angiostrongylus cantonensis, the rat lungworm. has an obligatory migratory phase through the host’s central nervous system, which can cause severe pathologic lesions. Natural infections in accidental hosts have been documented only in mammals, and to our knowledge, angiostrongyliasis in avian hosts has not been previously reported.
Managing Invasive Alien Mollusk Species in Rice by Ravindra C. Joshi, Department of Agriculture-Philippine Rice Research Institute (DA-PhilRice), Maligaya, Science City of Muñoz, Nueva Ecija 3119, Philippines (December 2005)
Summary. Once GAS has established its presence, its control is not easy. The economic, health, and environmental problems caused by GAS invasion are irreversible and the cost to remedy these is enormous. Conventional management practices to manage GAS are labor-intensive, uneconomical, and non-sustainable, and many are harmful to the environment. New options, however, are now being introduced that are environment-friendly and cost-effective. For example, the use of GAS for paddy weeding is a promising management option in rice fields where GAS is already present. Moreover, GAS can be used as food for humans and animals.
Studies on susceptibility of Pomacea canaliculata of different developmental stages to infection with Angiostrongylus cantonensis by He-xiang Liu, Yi Zhang, Xiao-nong Zhou, Shan Lv, Dan Zhu, Jin-qiang Lin, Li-sha Li, You-song Li, Wei-gang Yin, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China. (October 2005)
OBJECTIVE: To study the susceptibility of Pomacea canaliculata of different developmental stages to Angiostrongylus cantonensis infection.
METHODS: P. canaliculata snails breeding at laboratory were divided into four rank (I-IV) according to the weight, and infected with the first stage larvae of A. cantonensis from Fujian Province. Their mortality, infection rate, worm burden, and the size, development and distribution of larvae in snails were examined.
RESULTS: Snails at different developmental stages were readily infected with A. cantonensis. The infection rate was between 76% and 100%, with no significant difference among the groups (P>0.05). Snails at earlier developmental stage showed higher mortality. The heaviest worm burden and the largest number of snails harboring more than 100 larvae were found in snails of rank III. In general the larvae in snails showed a synchronous development in the groups. Sizes of the third stage larvae in snails of various ranks were homogeneous. The period before the third stage larva emergence and the time for a peak percentage of the larvae exhibited no significant difference among the four ranks. The larvae widely distributed in various parts of snails, with more in the lung and foot, and larvae from snails of different ranks could all infect rats successfully.
CONCLUSION: P. canaliculata of the four ranks can all be infected by the first stage larvae of A. cantonensis. Rank III snails may be better for studying the relationship between P. canaliculata and A. cantonensis. The potential role of young snails in angiostrongyliasis transmission should be recognized.
Factors affecting the distribution and abundance of the commensal Temnocephala iheringi (Platyhelminthes: Temnocephalidae) among the southernmost populations of the apple snail Pomacea canaliculata (Mollusca: Ampullariidae) by Pablo R. Martín, Alejandra L. Estebenet1 and Silvana Burela Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, 8000, Bahía Blanca, Argentina, Hydrobiologia, Volume 545, Number 1, (August 2005)
Abstract.Temnocephala iheringi is the most common temnocephalan inhabiting the mantle cavity of the apple snail Pomacea canaliculata, a freshwater neotropical gastropod that has become a serious rice pest in Southeastern Asia. T. iheringi has been recorded from Mato Grosso (Brazil) to water bodies associated with the Río de la Plata river (Argentina). During an extensive survey in the southern limit of the native area of P.␣canaliculata the presence of T. iheringi eggs was recorded in several apple snail populations, extending the known distribution of the commensal more than 400 km southwards. The aim of this study was to understand the factors affecting the distribution and abundance of T. iheringi among populations of P.␣canaliculata. Only 23% of the apple snail populations inhabiting streams harboured temnocephalans while the occurrence among lentic ones was 71%. T. iheringi was found mostly in populations of apple snails living in non-alkaline sites and where snails attaining sizes larger than 4 cm were very common. The prevalence of the temnocephalans in lentic populations was higher than 90%. The number of eggs on the shell (not including the umbilicus) ranged between 0 and 470 and was different among populations of P.␣canaliculata. The prevalence and number of eggs were lower in the lotic populations, except for a stream population immediately downstream of a lake with commensals. There was no difference between males and females of P. canaliculata neither in the prevalence nor in the number of eggs on the shell. The southernmost population of the world of P. canaliculata harbours commensals that tolerate cold winter water temperatures (4–5 °C), as well as its host. On the other hand, T. iheringi was found only in sites with bicarbonate concentrations lower than 6.6 meq l−1, suggesting that the tolerance of the commensal is very much lower than that of the apple snail (up to 9.95 meq l−1). The number of worms inside each snail or the life history variation of P. canaliculata could explain the influence of the size of the snails on the occurrence of T. iheringi. In the big-sized snails, where the number of commensals is higher, the probability of survival of at least one worm is also higher, specially during the hibernation period, when crawling and feeding are null and snails remain buried. On the other hand, P. canaliculata snails from lentic populations are generally bigger and mostly iteroparous, while those inhabiting streams are smaller and semelparous. In these populations the snails have access to mate only with snails of their same cohort, while in iteroparous populations they can copulate with individuals of other cohorts, allowing the inter-generation transmission of worms and the long term persistence of the population of commensals.
MOLLUSCICIDAL ACTIVITY OF VULGARONE B FROM ARTEMISIA DOUGLASIANA (BESSER) AGAINST THE INVASIVE, ALIEN, MOLLUSC PEST, POMACEA CANALICULATA (LAMARCK) by Joshi, R.C., Meepagala, K.M., Sturtz, G., Cagauan, A.G., Mendoza, C.O., Dayan, F.E., Duke, S.O. (July 2005)
Abstract. Golden apple snail (GAS), Pomacea canaliculata (Lamarck), is a native of South America. It was introduced to Asia as a protein source and a source of income for farmers in the rural underdeveloped areas. However, the demand dropped because GAS was found to transfer the rat lungworm parasite (Angiostrongylus cantonensis) to humans if undercooked GAS is consumed. Farmers growing GAS abandoned their cultures, and the snails were disposed of without precautions. GAS soon invaded the rice fields, where it found an ideal habitat and abundant food supply. Previous studies show that vulgarone B has a molluscicide activity against ram’s horn snail (Planorbella trivolvis), which is a pest in commercial catfish production ponds, particularly in the Southeastern part of the USA. In this study, vulgarone B was tested against GAS. Laboratory bioassays indicated that vulgarone B had comparable activity to that of the commercial synthetic molluscicide (metaldehyde), both with an LC50 at 24 hours of about 30 µM. Sprayed vulgarone B is not toxic to rice seedlings at concentrations that caused 100% mortality of GAS. However, it caused chlorosis when incorporated into agar on which rice seedlings were grown. Ovicidal activity was tested on egg masses at various ages (1, 3, 5, 7, and 10 days) at concentrations ranging from 1-400 µM, but no ovicidal activity was found.
INVADERS FROM THE SOUTH: APPLESNAIL (POMACEA CANALICULATA) ECOLOGY AND LIFE HISTORY by Rebecca K. Marfurt and Romi L. Burks, Department of Biology, Southwestern University, 1001 East University Avenue, Georgetown, TX 78626, 4th BIENNIAL SYMPOSIUM, Freshwater Mollusk Conservation Society, St. Paul, Minnesota, USA, May 15-18, 2005
Abstract. Exposure to multiple vectors increases the susceptibility of aquatic ecosystems to invasion. Transferred through the aquarium trade, channeled applesnails (Pomacea canaliculata) may negatively impact native ecosystems through their rapid reproduction and voracious appetite for aquatic plants. Current management efforts suffer from a lack of basic data regarding abiotic and biotic impacts on applesnails. To address this, we first tested how salinity affected snail mortality. Both adults and hatchlings tolerated salinity levels as high as 8 ppt. Higher levels quickly led to mortality. To examine salinity impacts on feeding, adult snails received lettuce and hatchlings fed on algae covering stone tiles. Adult feeding increased significantly at 8 ppt compared to 0 ppt (p = 0.002), while hatchling consumption did not vary (p = 0.284). To address biotic factors, we tested how applesnails responded behaviorally to predatory cues from fish, turtles, crayfish and adult applesnails. Our results indicated that fish and crayfish prompted similar predator avoidance behaviors in hatchlings (p 0.05), whereas adult snails consumed more applesnails (p < 0.001). Overall, our experiments indicated that applesnails tolerate abiotic stress and respond to likely predators. With high reproduction rates and varied ecological strategies, applesnails might be the next zebra mussel in terms of their economic and ecological impact. Research providing insight into their basic ecology can foster management efforts.
Herbivory on Aquatic Vascular Plants by the Introduced Golden Apple Snail (Pomacea canaliculata) in Lao PDR by Carlsson, N.O.L. and J.O. Lacoursière, Biological Invasions 7(2): 233-241 (2005)
Abstract. The effect of naturally found densities of the exotic and herbivorous golden apple snail (Pomacea canaliculata) on three dominant aquatic plants – duckweed (Lemna minor), water hyacinth (Eichhornia crassipes) and morning glory (Ipomoea aquatica) – was assessed in a wetland survey and quantified in a field experiment in Laos in southeast Asia. Snail grazing reduced plant biomass, but plant species were differently affected by grazing. Duckweed had almost disappeared after 6 and water hyacinth after 21 days, whereas morning glory remained at 80% of initial biomass after 32 days. Snail growth was lowest on morning glory and, when all plant species were simultaneously presented to snails, this plant was not preferred. We suggest that the negative effect the golden apple snail had on the growth of these plant species in field enclosures is present in the natural environment as well. This new and intense herbivory could have serious negative effects on invaded freshwater ecosystems in this region.
ANNOTATED BIBLIOGRAPHY OF THE FLORIDA APPLESNAIL, POMACEA PALUDOSA (SAY), FROM 1824 TO 1999 byRichard L. Turner1 and Paula M. Mikkelsen2, 1 Department of Biological Sciences, Florida Institute of Technology, 150 W. Melbourne,Florida, U.S.A.; 2 Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024-5192, U.S.A.; Nemouria 48:1-188, December 1, 2004
Abstract. The Florida apple snail, Pomacea paludosa (Say, 1829), inhabits freshwater rivers, lakes, and wetlands of the southeastern United States and Cuba, where it is prey to several species of birds, reptiles, and fish, particularly the snail kite, limpkin, American alligator, and redear sunfish. It has additionally been a staple in the diet of several native human populations. Introduction of exotic aquatic vegetation and the management practices of the 1900s have impacted the availability of P. paludosa to its predators, some of which are listed on federal and state registries of species that are endangered, threatened, or of special concern. Its association with the snail kite, limpkin, and Everglades has marked it by federal and state biologists as a species in great need of study.
The present work is a bibliography of 673 annotated works on the Florida apple snail through 1999, 175 yr since its original description in 1824 by Thomas Say. The works are mostly primary and secondary literature, but some are fiction, videotapes, stamps, and commercial artwork, including one sculpture. Newspaper articles and websites are excluded. Early publications dealt with taxonomy, distribution, and the observations of naturalists. More recent documents, including many unpublished agency reports, have focused on ecological studies, particularly with regard to the management and restoration of wetlands and to the population biology of the snail kite.
An early impediment to our knowledge of apple snail biology was the tendency of naturalists of the 1700s and 1800s to visit Florida during winter, a season when both mosquitoes and apple snails are less active. A more recent impediment has been the use of specimens of uncertain or incorrect identity from the aquarium trade for descriptive and experimental studies in laboratories around the world.
Aquatic Snails, Passive Hosts of Mycobacterium ulcerans by Laurent Marsollier, Tchibozo Sévérin, Jacques Aubry, Richard W. Merritt, Jean-Paul Saint André, Pierre Legras, Anne-Lise Manceau, Annick Chauty, Bernard Carbonnelle, and Stewart T. Cole (October 2004)
Abstract. Accumulative indirect evidence of the epidemiology of Mycobacterium ulcerans infections causing chronic skin ulcers (i.e., Buruli ulcer disease) suggests that the development of this pathogen and its transmission to humans are related predominantly to aquatic environments. We report that snails could transitorily harbor M. ulcerans without offering favorable conditions for its growth and replication. A novel intermediate link in the transmission chain of M. ulcerans becomes likely with predator aquatic insects in addition to phytophage insects. Water bugs, such as Naucoris cimicoides, a potential vector of M. ulcerans, were shown to be infected specifically by this bacterium after feeding on snails experimentally exposed to M. ulcerans.
Lethal and non-lethal effects of multiple indigenous predators on the invasive golden apple snail (Pomacea canaliculata) by Nils Carlsson, Åsa Kestrup, Monica Mårtensson and Per Nyström , Department of Ecology, Limnology, Lund University, S-223 62 Lund, Sweden (July 2004
1. We investigated the individual and combined effects of two predators (the climbing perch, Anabas testudineus, and the wetland crab, Esanthelphusa nimoafi) indigenous to wetlands in Laos, on the behaviour and survival of the invasive South American golden apple snail (Pomacea canaliculata). The snail is considered a pest, consuming large amounts of rice and other aquatic vegetation in the region.
2. Snail avoidance reactions to released predator chemical cues were investigated in aquaria while the effects of predators on a mixed snail population were studied in field enclosures that contained native aquatic plants (Salvinia cucullata, Ludwigia adscendens and Ipomoea aquatica).
3. In the aquaria experiment, neonate (2-3 mm) and medium-sized snails (8-10 mm) responded to fish chemical cues by going to the surface, whereas adult snails (35-40 mm) went to the bottom. In contrast, no size class of snails reacted to chemical cues released by crabs.
4. In the field experiment, fish reduced the abundance of neonate snails, and crabs reduced the abundance of all size classes. The effect of the combined predators could not be predicted from the mortality rate observed in single predator treatments. The survival of neonate and medium-sized snails was greater and of adults less than expected. The presence of predators did not affect egg production. Snails consumed significant amounts of plants despite the presence of predators.
5. Our findings suggest that some indigenous Asian predators have lethal and sublethal effects on P. canaliculata that depend on snail size and predator type. When in the presence of several predators the response of snails to one predator may either increase or decrease the vulnerability of snails to the others.
A Simple Technique for Trapping Siren lacertina, Amphiuma, and Other Aquatic Vertebrates by Steve A. Johnson and William J. Barichivich, Journal of Freshwater Ecology, Volume 19, Number 2 (June 2004)
Abstract. We describe a commercially-available funnel trap for sampling aquatic vertebrates. The traps can be used in heavily vegetated wetlands and can be set in water up to 60 cm deep without concern for drowning the animals. They were especially useful for capturing the aquatic salamanders Siren lacertina and Amphiuma means, which have been difficult to capture with traditional sampling methods. They also were effective for sampling small fishes, particularly centrarchids, and larval anurans. In total, 14 species of amphibians, nine species of aquatic reptiles, and at least 32 fish species were captured. The trap we describe differs significantly from traditional funnel traps (e.g., minnow traps) and holds great promise for studies of small, aquatic vertebrates, in particular Siren and Amphiuma species.
Nitrate Impacts on Florida Apple Snail (Pomacea paludosa) Survival and Growth by Norah M. Corrao, Philip C. Darby, and Christopher M. Pomory, Department of Biological Sciences, University of West Florida, American Malacological Society, Sanibel 2004
Abstract. Nitrate pollution in first magnitude springs in Florida has been suggested as a possible reason for declining Florida apple snail (Pomacea paludosa) populations. Based on other nitrate toxicity studies, we hypothesized that survival and growth would not be affected at nitrate concentrations typically seen in springs (0–25 ppm nitrate). Laboratory studies were performed to examine nitrate impacts on snail survival and growth. Field data were used to determine if there was a correlation between spring snail density and spring nitrate concentration. Adult and juvenile LC50s could not be determined based on the low mortality rates. Juvenile EC50 values were determined to be 587.35 and 617.65 ppm nitrate, for two trials, respectively. No correlation was found between snail density and spring nitrate concentration. Elevated nitrate concentrations do not seem to affect apple snail survival in the laboratory. We suggest that other factors, including habitat structure and invasion of exotic plants, help determine the distribution of Florida apple snails.
Invasive Apple Snails (Ampullariidae) in Hawaii and Southeast Asia by Robert H. Cowie, Center for Conservation Research and Training, University of Hawaii American Malacological Society, Sanibel 2004
Abstract. Apple snails (Ampullariidae) were first introduced to Southeast Asia around 1980, initially probably from Argentina to Taiwan. The species introduced is usually referred to as Pomacea canaliculata. The purpose of the introduction was to develop aquaculture of the snails both for local consumption and as gourmet export items. Since 1980 and for the same purposes, apple snails have been introduced to most countries in Southeast Asia. However, they were not eagerly consumed locally and the export market did not develop. The number of introductions to Southeast Asia is unknown, but there have been suggestions that more than one Pomacea species have been introduced. Molecular genetic research is addressing this possibility. Four Ampullariidae species have been recorded from Hawaii, as follows. A South American species, Pomacea bridgesii, was first recorded in 1962 and is now locally established; P. paludosa, native to the southeastern USA and first recorded in 1990, may not be established; both were probably introduced via the aquarium trade. Pomacea canaliculata, first recorded in 1990, has spread rapidly throughout the islands. Pila conica, from Southeast Asia, was first recorded in 1966 but remains only locally distributed. In Southeast Asia, Pomacea canaliculata (and perhaps other species), has become established in the wild and is now the top pest of wetland rice. In Hawaii, this species is a major pest of wetland taro. Control measures have been implemented, but with little success. Other areas in southern Asia, as well as Australia, are not yet infested but are at great risk.
Invading Herbivory: The Golden Apple Snail Alters Ecosystem Functioning in Asian Wetland by Nils O.L. Carlsson, Christer Bronmark, and Lars-Anders HanssonDepartment of Ecology/Limnology, Ecology Building, Lund University, SE-223 62 Lund, Sweden Ecology, 2004, vol. 85, no. 6, p. 1575-1580 (December 2003)
Abstract. We investigated the effects of an exotic snail, the golden apple snail (Pomacea canaliculata) on biodiversity and ecosystem functioning in tropical wetland ecosystems. This large snail (up to 80-mm shell height) has invaded large parts of Southeast Asia during recent decades. A survey of natural wetlands in Thailand showed that high densities of the snail were associated with almost complete absence of aquatic plants, high nutrient concentrations, and high phytoplankton biomass, that is, a complete shift in both ecosystem state and function. A field experiment demonstrated that grazing by the snail can cause the loss of aquatic plants, a change toward dominance of planktonic algae, and thereby a shift toward turbid water. Estimates of biologically fixed nutrients released through snails grazing on aquatic plants revealed that phosphorus releases were sufficient to explain the recorded increase in phytoplankton biomass. Hence, our study demonstrates how an herbivore may trigger a shift from clear water and macrophyte dominance to a turbid state dominated by planktonic algae. This shift and the continuing aggressive invasion of this exotic species are detrimental to the integrity and functioning of wetland ecosystems, and to the services these provide in Southeast Asia.
Isolation and characterization of pathogens attacking Pomacea canaliculata by Wimol Chobchuenchom and Amaret Bhumiratana, Faculty of Medical Technology, Rangsit University, Muang, Prathumthani, 12000, Thailand, Department of Biotechnology, Faculty of Science, Mahidol University, RAMA VI, Bangkok, 10400, Thailand, World Journal of Microbiology and Biotechnology, Volume 19, Number 9, (December 2003)
Abstract. Seven microorganisms capable of killing Pomacea canaliculata were isolated from soil samples obtained from various agricultural areas of Thailand. The identification of these microorganisms was performed using microscopic examination and biochemical tests. Five strains were identified as Pseudomonas aeruginosa and were designated P. aeruginosa 19.1, 21.2.1, B1.1, P1 and P2. The other two strains were identified as Pseudomonas fluorescens and were designated P. fluorescens 13.1 and Ct1. Pathogenicity studies of these microorganisms to P. canaliculata (Lamarck) were performed and characterized by LC50 levels. The LC50 levels of non-autoclave-treated and autoclave-treated cell suspensions to P. canaliculata were found to be 3.56 × 104–1.35 × 106 c.f.u./ml and 3.09 × 104 to 1.23 × 106 c.f.u./ml, respectively.
Expansion of the Golden Apple Snail, Pomacea canaliculata, and Features of Its Habitat by Ito Kenji Department of Entomology and Nematology National Agricultural Research Center Kannondai 3-1-1, Tsukuba, Ibaraki 305-8666, Japan, (November 2003)
Excerpt. Paddy fields in this area are dry from September to April, but there is water in the canals all year round. The results of the survey suggested that in the autumn, the snail was found in both paddy fields and canals, but that the snail overwintered successfully only in some of the canals. All snails in dry paddy fields died during the winter.
Alarm response of hatchlings of the apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae), to aqueous extracts of other individuals by Katsuya Ichinose, Yoichi Yusa, and Kazuhiro Yoshida, National Agricultural Research Center for Kyushu Okinawa Region, Suya 2421, Nishigoshi Kikuchi-gun Kumamoto-ken, 861-1192, Japan, Ecological Research, Volume 18, Number 2 / March, 2003
Abstract. We examined how hatchlings of the freshwater snail, Pomacea canaliculata, responded to aqueous extracts of conspecific hatchlings. Three, 3-day-old hatchlings were macerated in deionized water (1 mg hatchling per 1 ml water). When 0.5 ml of the aqueous extract was added to a test tube containing 10 hatchlings of the same age and 50 ml of water, the hatchlings in the water began to crawl out of the water within 5 min. The proportion of hatchlings that crawled out of the water approached 0.6–0.9 after 1 h, but gradually decreased to 0.4 after 24 h. The relatedness between the live and the macerated hatchlings had no significant influence on the response. Hatchlings of egg masses obtained either in the laboratory or in the wild responded similarly to aqueous extracts of hatchlings from either egg mass. This suggests that the conditions under which the egg masses were incubated or the conditions that their parents had experienced had no effect on the hatchlings response. When compared with experiments reported on other aquatic animals, we consider the behavior of the hatchlings to be an alarm response of escaping from predators.
SHELL INTERPOPULATION VARIATION AND ITS ORIGIN IN POMACEA CANALICULATA (GASTROPODA: AMPULLARIIDAE) FROM SOUTHERN PAMPAS, ARGENTINA by ALEJANDRA L. ESTEBENET and PABLO R. MARTÍN, Universidad Nacional del Sur, Departamento de Biología, Bioquímica y Farmacia, San Juan 670, 8000 Bahía Blanca, Argentina, J. Moll. Stud., 69, 301-310 (March 2003)
Abstract. Despite its widely recognized conchological variation, studieson the shell variability of Pomacea canaliculata are limitedto its sexual and ontogenetic components. Here, we analyse theinterpopulation variation in conchological and somatic traits,and sex-related growth patterns of P. canaliculata to discoverif it is ecophenotypically or genetically determined. Pomaceacanaliculata showed variation in shell shape, shell and bodyweight, and body ash content among populations from three environmentallydifferent sites. Shell shape was also different when snails fromthe three sources were reared under homogeneous laboratory conditions, indicatinga genetic basis for the differences. Shell shapes of laboratory snailsdiffered from their field counterparts, suggesting an environmental influenceon shape. The genetic differentiation of shell shape among the studiedpopulations does not seem to be the outcome of adaptation tolocal conditions or of genetic drift, but is probably a sideeffect of adaptive differentiation in some life-history traits.On the other hand, weight and ash content differences disappearedunder homogeneous conditions, suggesting that their variationis mainly ecophenotypic. Variability in shell thickness, body weightand ash content seems to be more related to trophic availabilitythan to water chemistry. In the laboratory, females showed slightlyhigher growth rates than males, but these inter-sex differencesvaried among snails from the three sources. However, shell lengthwas not different between sexes in the field populations, probablydue to a greater effect of food shortage on female growth rates.The widespread pattern that shells of freshwater snails from contrastingenvironments are different has been attributed mostly to cumulativeenvironmental effects or to adaptation to local conditions. However,we suggest that different shell shapes could arise as a collateral outcomeof genetically different reproductive behaviours and that itwould be misleading to study the shell as a trait exposed separatelyto selective pressures or environmental influences.
Environmental fate and effects of the lampricide bayluscide by Dawson, V. K., Journal of Great Lakes Research, v. 29, no. Suppl. 1, p. 475-492. (2003)
Abstract. Bayluscide is an additive to TFM that increases the effectiveness of TFM as a lampricide. A review of the literature was undertaken to determine the environmental fate and effects of Bayluscide. Niclosamide (2′, 5-dichloro-4′-nitrosalicylanilide), the active ingredient of Bayluscide, degrades rapidly in natural water and sediment systems, however, the rate of degradation is very slow in autoclaved samples. This difference suggests that degradation under laboratory conditions is dependent on microbial activity and hydrolysis plays a minor role in degradation of niclosamide. The major degradation product of niclosamide has been reported to be aminoniclosamide (2′,5-dichloro-4′-aminosalicylanilide), which represented more than 50% of the residues extractable from sediments. Significantly more of the chemical is adsorbed to sediments with higher organic content and at lower pH’s. The mobility of niclosamide in soil can be characterized as slight to medium; the estimated leaching distance would range from 0 to > 25 cm depending on the soil type and pH. The active ingredient of Bayluscide (niclosamide) is decomposed by ultra-violet light depending on the intensity and duration of the exposure. The uptake of residues by most invertebrates exposed to super 14C-niclosamide is fairly rapid and equilibrium is reached within 24 h. About 90% of the accumulated residues were lost within 48 h after the organisms were transferred to clean flowing water. As with invertebrates, fish rapidly accumulate and eliminate residues of niclosamide. Three distinct residues were isolated from the extracts of edible fillet tissue; parent niclosamide, the glucuronide conjugate of niclosamide, and the sulfate ester of niclosamide. Aquatic plants and agricultural crops do not appear to be adversely affected at concentrations of Bayluscide used for lamprey or snail control. Mayflies (Hexagenia sp.). tend to be susceptible to TFM, but are relatively resistant to the effects of exposure to Bayluscide. Bayluscide was originally developed as a molluscicide to eliminate snails. Therefore, it is not surprising that mollusks are extremely sensitive to Bayluscide. Oral, dermal, and ocular administration of Bayluscide to mammals resulted in no clinical signs of systemic toxicity. Tests of the chronic effects of Bayluscide indicated that it is not mutagenic or carcinogenic. Bayluscide is not persistent in the environment; it breaks down in natural water and sediment systems through hydrolysis, photolysis, and microbial degradation. Given the limited use and tight control maintained by the U.S. Fish and Wildlife Service during applications of lampricides, Bayluscide presents minimal risk to human health and safety of the environment.
Molluscicidal Saponins from Sapindus mukorossi, Inhibitory Agents of Golden Apple Snails, Pomacea canaliculata by Hui-Chi Huang,Sin-Chung Liao,Fang-Rong Chang,Yao-Haur Kuo,and Yang-Chang Wu, Graduate Institute of Natural Products, Kaohsiung Medical University, Taiwan, Department of Nursing, Tzu Hui Institute of Technology, Taiwan J. Agric. Food Chem., 51 (17), pp 4916–4919, 2003
Abstract. Extracts of soapnut, Sapindus mukorossi Gaertn. (Sapindaceae) showed molluscicidal effects against the golden apple snail, Pomacea canaliculata Lamarck. (Ampullariidae) with LC50 values of 85, 22, and 17 ppm after treating 24, 48, and 72 h, respectively. Bioassay-directed fractionation of S. mukorossi resulted in the isolation of one new hederagenin-based acetylated saponin, hederagenin 3-O-(2,4-O-di-acetyl-α-l-arabinopyranoside)-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (1), along with six known hederagenin saponins, hederagenin 3-O-(3,4-O-di-acetyl-α-l-arabinopyranoside)-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (2), hederagenin 3-O-(3-O-acetyl-β-d-xylopyranosyl)-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (3), hederagenin 3-O-(4-O-acetyl-β-d-xylopyranosyl)-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (4), hederagenin 3-O-(3,4-O-di-acetyl-β-d-xylopyranosyl)-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (5), hederagenin 3-O-β-d-xylopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (6), and hederagenin 3-O-α-l-arabinopyranoside (7). The bioassay data revealed that 1−7 were molluscicidal, causing 70−100% mortality at 10 ppm against the golden apple snail.
Parastrongylus (= Angiostrongylus) cantonensis Now Endemic in Louisiana Wildlife By Kim, D. Y., Stewart, T. B., Bauer, R.W., and Mitchell, M., Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge 7080, Journal of Parasitology, 88(5): 1024-6 (October 2002)
Abstract. Parastrongylus (=Angiostrongylus) cantonensis, a lung worm of rats, was first reported in the United States in 1987, with a probable introduction by infected rats from ships docking in New Orleans, Louisiana, during the mid-1980s. Since then, it has been reported in nonhuman primates and a boy from New Orleans, and in a horse from Picayune, Mississippi, a distance of 87 km from New Orleans. Parastrongylus cantonensis infection is herein reported in a lemur (Varencia variegata rubra) from New Iberia, Louisiana, a distance of 222 km from New Orleans, and in a wood rat (Neotoma floridanus) and in 4 opossums (Didelphis virginiana) from Baton Rouge, Louisiana, a distance of 124 km from New Orleans. The potential of a great variety of gastropods serving as intermediate hosts in Louisiana may pose a threat to wildlife as well as to domesticated animals in the areas where infected Norway rats (Rattus norvegicus) are present.
PROCEEDINGS OF THE SPECIAL WORKING GROUP ON THE GOLDEN APPLE SNAIL (POMACEA SPP.) The Seventh International Congress on Medical and Applied Malacology (7th ICMAM) Los Baños, Laguna, SEAMEO Regional Center for Graduate Study and Research in Agriculture (SEARCA), Philippines (October 2002)
Molluscs as crop pests by G. M. Barker, Published by CABI, ISBN 0851993206, 468 pages, See Chapter 5 Apple Snails as Agricultural Pests: their Biology, Impacts & Management by Robert H. Cowie, pp. 154-191, 2002
Excerpt. Some species could be considered preadapted for living in rice paddies, taro patches, and other similar artificial habitats in which aquatic crops are grown. There may be differences in the habitat among closely related species. For instance, in Argentina, Scott (1957) reported that Pomacea canaliculata inhabited relatively still water, while the almost indistinguishable Pomacea insularum was found in rivers.
MOVEMENTS OF FLORIDA APPLE SNAILS IN RELATION TO WATER LEVELS AND DRYING EVENTS by Philip C. Darby, Robert E. Bennetts, Steven J. Miller, and H. Franklin Percival in Wetlands, Vol. 22, Issue 3 (September 2002)
Abstract. Florida apple snails (Pomacea paludosa) apparently have only a limited tolerance to wetland drying events (although little direct evidence exists), but their populations routinely face dry downs under natural and managed water regimes. In this paper, we address speculation that apple snails respond to decreasing water levels and potential drying events by moving toward refugia that remain inundated. We monitored the movements of apple snails in central Florida, USA during drying events at the Blue Cypress Marsh (BC) and at Lake Kissimmee (LK). We monitored the weekly movements of 47 BC snails and 31 LK snails using radio-telemetry. Snails tended to stop moving when water depths were 10 cm. Snails moved along the greatest positive depth gradient (i.e., towards deeper water) when they encountered water depths between 10 and 20 cm. Snails tended to move toward shallower water in water depths 50 cm, suggesting that snails were avoiding deep water areas such as canals and sloughs. Of the 11 BC snails originally located in the area that eventually went dry, three (27%) were found in deep water refugia by the end of the study. Only one of the 31 LK snails escaped the drying event by moving to deeper water. Our results indicate that some snails may opportunistically escape drying events through movement. The tendency to move toward deeper water was statistically significant and indicates that this behavioral trait might enhance survival when the spatial extent of a dry down is limited. However, as water level falls below 10 cm, snails stop moving and become stranded. As the spatial extent of a dry down increases, we predict that the number of snails stranded would increase proportionally. Stranded Pomacea paludosa must contend with dry marsh conditions, possibly by aestivation. Little more than anecdotal information has been published on P. paludosa aestivation, but it is a common adaptation among other apple snails (Caenogastropoda: Ampullaridae).
Influence of common carp on apple snail in a rice field evaluated by a predator – prey logistic model by Ichinose K.; Tochihara M.; Wada T.; Suguiura N.; Yusa Y., International Journal of Pest Management, Volume 48, Number 2, pp. 133-138(6) (April 2002)
Abstract. The hypothesis that common carp can be used for the control of apple snails in rice fields was tested experimentally. In a rice field, 12 plots of 4×5 m were set and enclosed by plastic walls to prevent snail emigration and immigration. The experiment continued from June to September. Three replicated treatments were used for the plots: zero, four and 12 carp were released, giving carp densities of 0.0, 0.2 and 0.6 m-2, respectively. Snail densities were estimated by the Jolly-Seber mark-recapture method. Newly laid egg masses were counted and measured for size, and hatching was monitored. The numbers of eggs per egg mass (y) were estimated using a regression equation obtained from the product of the maximum length and width of the egg mass (x): y =0.10 x1.24. Using these measures and the monthly mean hatching rate obtained from eggs laid in two outdoor aquaria from April to September, the number of hatched eggs was used to estimate the birth rate over a given time. A logistic model incorporating these estimates revealed that the snail population proliferated only in the zero-carp plot throughout the experiment. The study, together with other reports on snail longevity, predicts that a snail population would be eliminated in 2 years at a stocking density of 2000 carp hectare-1, if no immigration of the snail occurred.
Interpopulation variation in life-history traits of Pomacea canaliculata (Gastropoda : Ampullariidae) in southwestern Buenos Aires Province, Argentina by Martin PR, Estebenet AL Univ Nacl Sur, Dept Biol Bioquim & Farm, RA-8000 Bahia Blanca, Buenos Aires, Argentina (2002)
Abstract. The Argentinean apple snail Pomacea canaliculata is a freshwater gastropod with a high interpopulation variation in shell shape, size and thickness. Previous experimental studies have shown that many life-history traits are highly dependent on rearing conditions. Three natural populations located in one same drainage basin and climatic regime showed marked differences in birth, maturity and maximum sizes. Most of this variation disappeared when newborns from each population were reared under homogeneous conditions in the laboratory, indicating its ecophenotypic origin. However, a significant variation in reproductive, growth and survival patterns attributable to genetic differences among the source populations was still discernible among laboratory cohorts. The three sites studied represent a marked gradient in stability and food availability. Females from the most unstable and poorer site showed a faster prematurity growth and a higher oviposition rate than those from the most stable and productive site. This higher oviposition rate was associated with bigger clutches and a higher mortality rate. The different patterns of survival and somatic and reproductive allocation in the three populations, being heritable and adaptively correlated to different environmental conditions, could be considered as parts of different life-history strategies. Since the 1980s, P. canaliculata has become a serious pest of paddy fields in most Southeast Asian countries. Nearby and recently isolated populations of P. canaliculata from the same basin showed genetically different life-history strategies, so that different populations of this pest could require different control programs.
Pomacea canaliculata (Gastropoda: Ampullariidae): Life-history Traits and their Plasticity by ALEJANDRA L. ESTEBENET AND PABLO R. MARTÍN Universidad Nacional del Sur, Departamento de Biología, Bioquímica y Farmacia, San Juan 670, 8000 Bahía Blanca, Argentina. BIOCELL 2002
Exerpts. P. canaliculata distribution is basically tropical and subtropical, including the Amazonas and La Plata basins (Ihering, 1919); the southernmost record for the species –the southernmost apple snail in the world– is Paso de las Piedras reservoir (38o 24’S), south of the Buenos Aires province, Argentina (Martín et al., 2001). Mean annual air temperature ranges from 25º to 14ºC, with almost null seasonal thermal amplitudes at low latitudes and up to 18ºC in southern Buenos Aires province. In spite of its overwhelming influence on most aspects of the biology of P. canaliculata, an hydrological discontinuity, not temperature, is probably the main factor impeding the spread of apple snails further South in Buenos Aires province (Martín et al., 2001).
Population dynamics, regulating mechanisms and the snails’ role in aquatic systems are all unknown. An environmentally sound solution to the problem of P. canaliculata as an invader requires an integrated and rational population management that will not be achieved until the basic aspects of its ecology are investigated.
Size and age at first copulation and spawning of the apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae) by ESTOY G F JR(Gifu Univ., Gifu, Jpn), YUSA Y(National Agricultural Res. Center For Kyushu Okinawa Region, Kumamoto, Jpn), WADA T(National Agricultural Res. Center For Kyushu Okinawa Region, Kumamoto, Jpn), SAKURAI H (Gifu Univ., Gifu, Jpn), TSUCHIDA K (Gifu Univ., Gifu, Jpn), Appl Entomol Zool, Volume 37, Number 1, 199-205 (2002)
Abstract. The size and age at first copulation and spawning of the apple snail, Pomacea canaliculata, were determined at three food levels under laboratory conditions(14L:10D; 25.DEG.C.). Males fed at a low food level started copulation at smaller sizes than males at higher food levels. However, age at first copulation was similar among snails at all food levels. The food level appeared to affect the penis sheath length at maturity, although the difference did not reach a statistically significant level. Females fed at the low food level delayed both first copulation and spawning longer than those at higher food levels. Consequently, their sizes at first copulation and spawning were smaller. The albumen gland of poorly fed snails was smaller at first copulation but comparable at maturity. The adaptive significance of these patterns in sexual maturity and their possible implications for the integrated management of this snail are discussed.
Environmental factors influencing overwintering success of the golden apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae), in the northernmost population of Japan by Kenji Ito,Insect Ecology Laboratory, National Agricultural Research Center, Tsukuba, Japan, Applied Entomology and Zoology, Vol. 37, No. 4, p. 655-661 (2002)
Abstract.The effect of environmental factors on the overwintering success of Pomacea canaliculata in the northernmost population of Japan was examined to determine the location of overwintering habitats in the agricultural water system. The snail overwintered only in a portion of the water canals, and did not overwinter in dried paddy fields. In the canal, the density of the snail was not necessarily high at the overwintering site before winter. Overwintering success in the water canal was not explained by temperature and water velocity, but by pH, dissolved oxygen (DO) and depth of water among the sampling sites. To determine the location of a proper overwintering site, it is important to investigate various habitats including places where the snail density is low, and measure various environmental variables including pH, DO, and depth of water.
Estimation of mortality of Pomacea canaliculata in paddy field during hibernation period using temperature data by SHOBU SHIN’ICHIRO(Saga Prefectural Agriculture Res. Center, JPN) MIKURIYA HATSUKO(Saga Prefectural Agriculture Res. Center, JPN) YAMAGUCHI JUN’ICHIRO(Saga Prefectural Agriculture Res. Center, JPN) ZEN SHOJIRO(Saga Prefectural Agriculture Res. Center, JPN) WADA MISAO(Saga Prefectural Agriculture Res. Center, JPN), Kyushu Okinawa Nogyo Kenkyu Seika Joho, Number 17, p. 431-432, (2002)
Abstract.In order to prevent Pomacea canaliculata that inhabits paddy field, the authors carried out laboratory experiment and the survey on the wintering conditionon in paddy fields over 7 years, and examined the relationship between low-temperature condition and shell death. There was the relation of y=-12.4x+120 between mean temperature in winter (December-February) and the mortality of Pomacea canaliculata in paddy fields in spring. From this relational expression, the mortality of Pomacea canaliculata in paddy fields can be estimated using mean temperature in the winter.
Exerpt. P. canaliculata distribution is basically tropical and subtropical, including the Amazonas and La Plata basins (Ihering, 1919); the southernmost record for the species –the southernmost apple snail in the world– is Paso de las Piedras reservoir (38o 24’S), south of the Buenos Aires province, Argentina (Martín et al., 2001). Mean annual air temperature ranges from 25º to 14ºC, with almost null seasonal thermal amplitudes at low latitudes and up to 18ºC in southern Buenos Aires province. In spite of its overwhelming influence on most aspects of the biology of P. canaliculata, an hydrological discontinuity, not temperature, is probably the main factor impeding the spread of apple snails further South in Buenos Aires province (Martín et al., 2001).
Preference and Feeding Behavior of Apple Snail, (Pomacea canaliculata), for Fruits and Vegetables by FUKUSHIMA YUSUKE, NAKAMURA SHIN’ICHIRO, FUJIYOSHI NOZOMU, Fukuoka Agric. Res. Cent., Japanese Journal of Crop Science, Volume 7, Number 3, pp. 432-436 (2001)
Abstract.To pursue the possibility of controlling apple snail damage on rice seedlings, the preferences and feeding behavior of the apple snail, under the use of fruits and vegetables as attractants in rice fields, were investigated. The apple snails showed higher preferences for specific fruits and vegetables, such as melons, watermelons, lettuce, eggplants, and tomatoes than for rice seedlings. Many more apple snails were observed adhering to and feeding on those fruits and vegetables than on rice seedlings when the seedlings, fruits and vegetables were simultaneously placed in one container. Most apple snails found their preferred food directly, or they moved to it after leaving unpreferred food within six hours. Moreover, the apple snails stayed on melons and eggplants for clearly a longer time period than on rice seedlings. Therefore it is suggested that vegetables in rice fields would attract the apple snails and may contribute to reduce apple snail damage on rice seedlings.
Equine Monocytic Ehrlichiosis (Potomac Horse Fever) in Horses in Uruguay and Southern Brazil by Fernando Dutra, Luı´z Filipe D. Schuch, Eduardo Delucchi, Bruna R. Curcio, Helen Coimbra, Margarida B. Raffi, Odir Dellagostin, Franklin Riet-Correa (2001)
Abstract. A disease named locally as “churrı´o or churrido equino” (i.e., equine scours) has occurred for at least 100 years in Uruguay and southern Brazil in farms along both shores of the Merı´n lake. This report describes cases of churrido equino and provides serologic, pathologic, and DNA-based evidence indicating that the disease is in fact equine monocytic ehrlichiosis (Potomac horse fever). Results of an epidemiological investigation conducted on an endemic farm are also presented. Clinical signs in 12 horses were fever, depression ,diarrhea, dehydration, and sometimes colic and distal hind limb edema. Postmortem findings of 3 horses were of acute enterocolitis. Inclusion bodies containing ehrlichial organisms were found in the cytoplasm of macrophages of the large colon of 1 horse. Eleven of the 12 horses were serologically positive to Ehrlichia risticii (indirect fluorescent antibody assay) and, of 3 paired samples, 2 showed sero conversion. Ehrlichia risticii DNA was identified by a nested polymerase chain reaction in peripheral blood of an affected horse. A healthy horse inoculated with peripheral blood from an affected horse developed the disease and antibodies to E. risticii. The disease had a peak incidence in March (summer) and was statistically associated with a marshy ecosystem near the Merı´n lake, where large numbers of Pomacea spp. (Ampullariidae) snails were found. Incidence density was almost 8 times higher in nonnative horses than in native horses. It was concluded that the previous diarrheic disease of horses known in Uruguay and southern Brazil as “churrido equino” is equine monocytic ehrlichiosis.
Predation on eggs of the apple snail Pomacea canaliculata (Gastropoda: Ampullariidae) by the fire ant Solenopsis geminate by Yoichi Yusa, Kyushu National Agricultural Experiment Station, Nishigoshi, Kumamoto 861-1192, Japan (2001)
Abstract. A field survey and two experimental manipulations were made to investigate the extent of predation on eggs of the apple snail Pomacea canaliculata (Lamarck) by the fire ant Solenopsis geminata (Fabricius) in the Philippines. First, when Pomacea egg masses found along levees of paddy fields were observed, more than half of them had some damage. More fire ants were observed near egg masses with higher degrees of damage. Secondly, when egg masses were experimentally placed on levees, on average 50% of the eggs were lost (removed or damaged) within two days in March and 38% were lost within three days in August. Thirdly, egg masses were placed in cups with or without water on levees; no eggs were lost when ants were successfully excluded by water. The proportion of lost eggs was highly variable among egg masses, but there was no difference between day and night. Possible use of this ant as a biocontrol agent for the apple snail is considered.
Estimating the overwintering mortality of the apple snail, Pomacea canaliculata (Lamarck) (Gastropoda : Ampullariidae) in a paddy field of southern Japan using temperature data by Syobu S., Mikuriya H., Yamaguchi J., Matsuzaki M., Zen S., Wada T., Saga Prefectural Agr Res Ctr, Saga 8402205, Japan (2001)
Abstract. Overwintering mortality of the apple snail, Pomacea canaliculata was investigated in a paddy field of Southern Japan for seven consecutive years. Field data and laboratory experiments revealed snails larger than 6.0 mm exhibited higher cold tolerance than small snails. Seven-years of field data showed that a linear regression explained a close relationship between the over-wintering mortality of snails larger than 6.0 nim and the cumulative low temperature calculated as the subtraction of the hourly temperature from 10 degreesC (CLT). A high correlation was also observed between overwintering mortality of snails and the mean temperature between December and February. Thus, temperature data seem to be practical and effective in estimating mortality of field snails during the winter.
Biological Control of Aquatic Pest Snails by the Black Carp Mylopharyngodon piceus by Frida Ben-Ami and Joseph Heller, Department of Evolution, Systematics & Ecology, The Hebrew University, Jerusalem, Israel, Biological Control, Volume 22, Issue 2 (October 2001)
Abstract. Some freshwater snail species are severe pests to human health or agriculture. We tested the hypothesis that the fish Mylopharyngodon piceus, the black carp, may serve as a biological control agent of two pest snails, Physella acuta (a bank-dwelling snail) and Melanoides tuberculata (a substratum-dwelling snail). Experiments were carried out in the laboratory and under controlled field conditions. In the laboratory, small fish (30–50 g) consumed up to about 300 P. acuta per day. Under field conditions in which snails could not shelter, and where fish were absent, snail densities peaked at 181% of their initial density. Where large M. piceus (4–5 kg) were present, snail densities during this period declined to 79%. Under field conditions in which snails could shelter among boulders, and where fish were absent, snail densities decreased to 80% of their initial density. Where large M. piceus (3–4 kg) were present, snail densities declined to 34%. In the laboratory, small fish (30–100 g) consumed 19 g of M. tuberculata/day at 19°C and 17 g at 25°C. There was no difference in the rate of consumption of snails placed upon the substratum or buried at two depths. We conclude that M. piceus may be an efficient biological control agent of pest snails that shelter among boulders and of substratum-dwelling species that bury into sand.
Evaluation of different duck varieties for the control of the golden apple snail (Pomacea canaliculata) in transplanted and direct seeded rice by Su Sin Teo Department of Agriculture, Agriculture Research Centre, Sabah, Malaysia, Crop Protection, Volume 20, Issue 7, Pages 599-604, August 2001
Abstract. This study investigated the potential of ducks for the control of the golden apple snail in irrigated rice. The varieties of duck recommended for the biological control of snail in decreasing preference were William Siam > Taiwan > Mallard > Peking > Muscovy. Cherry Valley, a variety with a bigger body size was not suitable for snail control because of its poor adaptation to rice field conditions. A density of 5–10 ducks ha−1 in continuous grazing for a period of 1–2 months significantly reduced the pest density from 5 snails m−2 to less than 1 snail m−2. This density of ducks was recommended for biological control of snails in rice. Timely release of ducks was crucial as they damaged young rice seedlings. In transplanted rice, it was appropriate to release the ducks when the seedlings were 4 weeks old. For direct seeded rice, a longer waiting period of 6 weeks was necessary. Numerically, ducks preyed on more snails in transplanted than in direct seeded rice, but the difference was not statistically significant. The increase in plant density under direct seeding probably reduced the browsing efficiency of the ducks. This difference would be expected to diminish under prolonged grazing. It is suggested that ducks were an effective biological control agent against the golden apple snail.
Current Status of the Golden Apple Snail in the Ifugao Rice Terraces, Philippines by R. C. Joshi, M. S. Delacruz, & E. C. Martin of the Philippine Rice Research Institute (PhilRice), Maligaya, Muñoz, 3119, Philippines, and J. C. Cabigat, R. G. Bahatan A. D. Bahatan E. H. Abayao Joe Choy-Awon Banaue, N. P. Chilagan A. B. Cayong Ifugao of Local Government Unit (LGU)-Department of Agriculture (DA), Municipality of Banaue, Ifugao, 3601, Journal of Sustainable Agriculture, Volume: 18 Issue: 2/3, ISSN: 1044-0046 (6/26/2001)
Abstract. The golden apple snail (GAS) was introduced in the Philippines between 1982 and 1984 to supplement sources of food protein of low-income Filipino farmers. However, in 1986, it began to damage heavily rice farms in northwestern Luzon. Its rapid multiplication and wide distribution threaten rice production and food security in the country. This study led by scientists and researchers of the DA-Phil Rice focused on farmers’ KAP (knowledge, attitudes and practices) survey and snail sampling. The current status and management of GAS in the IRT (Ifugao Rice Terraces) was determined with emphasis on ecological, and socioeconomic aspects. Farm interviews were conducted using a pretested questionnaire translated into Iloko (the local dialect), using a list of key issues but not limited by it. In-depth interviews gathered greater insights on farmers’ perceptions of the GAS problem. These were aimed at developing seasonal and historical profiles, and interaction matrices describing GAS development in the IRT. Secondary data from the MAO, CECAP, ITC, DA and key informants in the barangays were gathered to validate the interview data. Randomly selected and interviewed were 127 farmers from the 26 barangays in the Ifugao municipalities of Banaue, Hungduan, and Mayoyao. Women outnumbered men. Majorities of the farmers had average literacy and were aged 31-70 years old. They had substantially long rice farming experiences aside from non-farm activities such as woodcarving. Farmers ranked GAS as their main pest after earthworms and rats. GAS had invaded the IRT because of human intervention and lack of adequate basic knowledge of the pest. Farmers’ perceived a yield loss of 41-50% caused by GAS. Farmers in the IRT use many indigenous technologies, but their potential and integration will have to be validated. GAS was the only snail pest species found in the IRT irrespective of elevation. GAS females always outnumbered males, but operculum size varied with shell size, and could not be related to sex. The most common color encountered in the GAS samplings was golden brown. Specific technologies to manage GAS are needed in the IRT taking into account the indigenous technology and farmers’ knowledge, rather than making blanket recommendations which lowland farmers now use for GAS management. This is possible through the farmer-scientist participatory research, extension and training approach. The existing National IPM program of the Department of Agriculture could further strengthen this approach to promote other uses of GAS through the farmers’ field school.
Food of the Snail, Pomacea bridgesi, Introduced in India by G. Aditya and S. K. Raut, Ecology and Ethology Laboratory, Department of Zoology, University of Calcutta, India, in Current Science, Vol. 80, No. 8, 25 (April 2001)
Excerpt. The results indicate that the snails, Pomacea bridgesi, have a wide range of food acceptability. These snails would find no problem to establish their colony in India. Consequently, the native herbivorous, zoophagous and microphagous species would face severe competition for food, if P. bridgesi find access to the natural water bodies. This may lead to extinction of some indigenous species as is evident from the disappearance of different species belonging to the genus Pila in certain parts of south-east Asia. Besides, in the long run, to meet their need they may start feeding on the paddy plants, as has been noted in some countries where P. bridgesi has been introduced. Therefore, adequate measure is urgently needed to stop their access into the open-air water bodies in India.
COLLECTING FLORIDA APPLESNAILS (POMACEA PALUDOSA) FROM WETLAND HABITATS USING FUNNEL TRAPS by Philip C. Darby, Patricia L. Valentine-Darby, H. Franklin Percival, and Wiley M. Kitchens Wetlands pp. 308-311 (March 2001)
Abstract. Traditional methods for sampling aquatic macro-invertebrates are very labor-intensive and largely ineffective when attempting to collect Florida applesnails (Pomacea paludosa) from their natural wetland habitats. We found the use of funnel traps an effective alternative that decreased collection time ten-fold and required considerably less labor than throw traps. The funnel traps described herein can be used effectively for collecting applesnails in a variety of wetland habitat types and plant densities, and they may also be effective in catching other wetland organisms (e.g., Kinosternid turtles).
Evaluation of different duck varieties for the control of the golden apple snail (Pomacea canaliculata) in transplanted and direct seeded rice by Su Sin Teo Department of Agriculture, Agriculture Research Centre, Sabah, Malaysia, Crop Protection, Volume 20, Issue 7, Pages 599-604, August 2001
Abstract. This study investigated the potential of ducks for the control of the golden apple snail in irrigated rice. The varieties of duck recommended for the biological control of snail in decreasing preference were William Siam > Taiwan > Mallard > Peking > Muscovy. Cherry Valley, a variety with a bigger body size was not suitable for snail control because of its poor adaptation to rice field conditions. A density of 5–10 ducks ha−1 in continuous grazing for a period of 1–2 months significantly reduced the pest density from 5 snails m−2 to less than 1 snail m−2. This density of ducks was recommended for biological control of snails in rice. Timely release of ducks was crucial as they damaged young rice seedlings. In transplanted rice, it was appropriate to release the ducks when the seedlings were 4 weeks old. For direct seeded rice, a longer waiting period of 6 weeks was necessary. Numerically, ducks preyed on more snails in transplanted than in direct seeded rice, but the difference was not statistically significant. The increase in plant density under direct seeding probably reduced the browsing efficiency of the ducks. This difference would be expected to diminish under prolonged grazing. It is suggested that ducks were an effective biological control agent against the golden apple snail.
Non-indigenous land and freshwater mollusks in the islands of the Pacific: conservation impacts and threats. Invasive species in the Pacific: a technical review and draft regional strategy. South Pacific Regional Environment Programme by Robert Cowie, South Pacific Regional Environment Programme (2000)
Learning of the Apple Snail in Response to a Baited Trap by Ichinose Kaysuya, Proceedings of the Association of Plant Protection of Kysuhu, Japan, Vol. 6, pp. 74-77 (2000)
Abstract. The ability of the apple snail, Pomacea canaliculata, to learn either to avoid a trap or to come to obtain the bait was studied. The trap was made from a soft-drink bottle and included 10g bait inside. Thirty snails, painted individually with different numbers, were released in a tank placed outdoors. Collection of the snails by the trap was performed 17 times during the period 17 June to 30 July 1998. The proportion of individual snails trapped showed a significant normal distribution around a mean of 0.533.+-.0.034 SEM. The mean interval between snails being trapped was 4.11.+-.0.26 days and this did not differ significantly between individual snails. Neither the size, represented by shell length, nor the sex showed significant correlation with the interval. This interval was independent of how many times the snail had been trapped until the penultimate collection. These results indicate that whether or not a snail is trapped is determined by probability, and not by size or sex, nor how many times the snail has been trapped previously.
Food Preference and Reproductive Plasticity in an Invasive Freshwater Snail by Lori Lach, David K. Britton, Rebecca J. Rundell and Robert H. Cowie, Biological Invasions, Volume 27, Number 4, (December 2000)
Abstract. The freshwater apple snail Pomacea canaliculata has become a major crop pest in southeast Asia and Hawai”i and threatens natural wetland habitats in these regions and elsewhere. Deliberately introduced as a potential human food resource, it has also been proposed as a possible biocontrol agent against aquatic weeds. Various factors may facilitate its rapid invasion of new areas; we focus on two: growth rate and food preference. Our field observations and laboratory experiments suggest that in Hawai”i P. canaliculata reaches reproductive maturity in 10 months or more, less time than in its native temperate and seasonal Argentina, where it takes 2 years, but longer than in parts of southeast Asia, where it may take as little as 2 months. This increased growth rate, and thence reproductive rate, probably facilitate rapid population growth. Although P. canaliculata is usually considered an indiscriminate generalist macrophytophagous feeder, laboratory experiments indicated preferences among the dominant plants at our field site and growth rate differences when constrained to feed only on one of these plants. Water hyacinth (Eichhornia crassipes), a major invasive weed, was not preferred in food choice experiments, and snails offered only water hyacinth on which to feed did not differ in growth rate from unfed snails. Another important invasive weed, water lettuce (Pistia stratiotes), was also not preferred, but snails fed on it did grow, though not as quickly as those fed on green-leaf lettuce. Among the food plants offered in the experiments the native Vigna marina was the most preferred. Therefore, although a generalist, P. canaliculata exhibits some discrimination among food plants. We recommend that it not be introduced for use as a biological control agent for aquatic weeds.
Learning of the apple snail in response to a baited trap by ICHINOSE KATSUYA, Minist. of Agric., For. & Fish., Kyushu Natl. Agric. Exp. Stn., Proceedings of the Association for Plant Protection of Kyushu, Volume 46, pp. 74-77, (2000)
Abstract. The ability of the apple snail, Pomacea canaliculata (Lamarck) (Gastropoda: Ampullariidae), to learn either to avoid a trap or to come to obtain the bait was studied. The trap was made from a soft-drink bottle and included 10g bait inside. Thirty snails, painted individually with different numbers, were released in a tank placed outdoors. Collection of the snails by the trap was performed 17 times during the period 17 June to 30 July 1998. The proportion of individual snails trapped showed a significant normal distribution around a mean of 0.533.+-.0.034 SEM. The mean interval between snails being trapped was 4.11.+-.0.26 days and this did not differ significantly between individual snails. Neither the size, represented by shell length, nor the sex showed significant correlation with the interval. This interval was independent of how many times the snail had been trapped until the penultimate collection. These results indicate that whether or not a snail is trapped is determined by probability, and not by size or sex, nor how many times the snail has been trapped previously.