Birds, frogs, and farmers: A community-based mitigation project

This project worked with a Wisconsin farming community to assess their current practices for using the organophosphate insecticide, chlorpyrifos. We then worked with the farming community to assess whether or not chlorpyrifos was having an adverse effect on birds and amphibians living adjacent to corn fields where chlorpyrifos was applied. Farmers also devised mitigation measures to reduce adverse effects, by testing the insecticide, tefluthrin.; Approximately 300 red-winged blackbird (Agelaius phoeniceus) nests were monitored. We found no significant differences in nest success between the controls and treatment groups after a single application of granular formulation of chlorpyrifos.; The toxicity of ehlorpyrifos to adult leopard frogs (Rana pipiens ) was determined by placing frogs in an aqueous solution of chlropyrifos for 24-hours (concentrations of 50, 100, 200, and 400 mg active ingredient (a.i.)/L). The results indicate the dermal LC₅₀ to be >400 mg/1, and the lethal LOEC and NOEC were 400 and 100 mg/l, respectively. A series of behavioral tests were performed to identify sublethal effects. A pronounced effect of sex on the degree of observed abnormal behaviors occurred in females in the 100 and 400 mg/l groups. Brain cholinesterase levels in the 400 mg/1 treatment group showed a 14% inhibition from controls. Adult leopard frogs were placed in field enclosures for 24-hours after chlorpyrifos was applied. The field experiment did not provoke the same lethal or behavioral responses we found in the laboratory.; Newly metamorphosed American toads (Bufo americanus) were placed in field enclosures for 24-hours with a subsequent behavioral test. Our results did not find any significant lethal or behavioral effects.; Lastly, the toxicity of tefluthrin to adult leopard frogs was determined using aqueous concentrations of 0.078, 0.13, 0.22, 0.36, and 0.60 mg a.i./L. Results indicate the dermal LC₅₀ to be 0.50 mg a.i./L and the LOEC and NOEC to be 0.13 and 0.078 mg a.i./L, respectively. We found a significant good dose response curve for abnormal behaviors. Another experiment placed frogs in field enclosures for 24-hours after tefluthrin was applied. Results indicate that treatment frogs were not significantly different from control frogs.