Last November, I was contacted by Lauren Strachan Hall, Research Coordinator for Neudorff North America. Originating in Germany, this company has been a leader in creating natural pesticide products for over 150 years. Ms. Hall coordinates field research for Neudorff, whose guiding principle is to combine a high degree of efficacy with excellent environmental safety.
One of Neudorff’s products, called “Sluggo” (A.I.: 1% iron phosphate), has been effectively used on terrestrial snails in the U.S. and elsewhere, but it is not labeled for aquatic use in the United States. This company has successfully treated invasive, exotic Pomacea canaliculata and P. maculata in Europe and Asia using pelletized iron phosphate baits in water. Ms. Hall expressed an interest in testing a more concentrated product in development (A.I.: 3% iron phosphate), while the company considers E.P.A. registration for its aquatic use in the United States.
The protocol called for 8 replicates per treatment with the treatments being 0.5g, 1.0g, 2.0g and 4.0g of NEU1180 HP pellets, plus a “control” of flour-based pellets. The containers were 5.7L plastic containers (30cm X 15cm X10cm). The tops of the containers locked which is important with large Pomacea. Snails were collected from Wellman Pond, east of Tallahassee, Florida. The average weight of the snails was 150g (116g – 178g). Shell height averaged 7.3cm. The protocol called for testing the snails’ appetites at 4DAT, 8DAT, and 12 DAT. Cucumber slices proved to be attractive, long-lasting, and easy to weigh and monitor.
The 3% iron phosphate bait proved to be an attractive to the snails. In fact, the test product appeared more attractive than the flour-based, blank pellets used in the control. The pelletized bait, scattered evenly in the containers, was readily consumed by all snails. The snails were observed daily for “proof-of-life,” e.g. attachment to the side of the container or resistance to a gentle pull on a closed operculum. Deaths were recorded daily. The snails were fed single cucumber slices every 4 days and percent consumption was noted the following day.
In three simple bench tests, Neudorff’s 3% iron phosphate bait appeared to have dose-related, detrimental effects on adult Pomacea maculata in terms of appetite and survival. Supplemental food consumption was reduced by 77% in the 0.5g treatment, 75% in the 1.0g treatment, 100% in the 2.0g treatment, and 100% in the 4.0g treatment. At 12 DAT, survival averaged 92% in the control, 75% in the 0.5g treatment, 50% in the 1.0g treatment, 12.5% in the 2.0g treatment, and 25% in the 4.0g treatment.
Feeding was suppressed at all treatment rates and ceased completely at rates of 2.0g and 4.0g. At those higher rates, 75% of the adult snails were dead by 6DAT. Considering the environmental safety of iron phosphate and the current lack of any safe and effective alternatives, the negative impacts of Neudorff’s 3% iron phosphate bait on food consumption and survival are reasons for optimism for this product’s use to control adult Pomacea maculata. – – Jess Van Dyke