Impact of endosulphan and cypermethrin mixture on amphibians under field use for biotech soya bean production

摘要

This study presents results at a local scale of the impact of pesticide aerial applications containing a mixture of endosulphan and cypermethrin on anurans assessed by means of field evaluations. Additionally, effects were compared with laboratory toxicity tests in standardised conditions. Field assessment with native population allowed the detection of dead anuran larvae of the species present in the stream of water after fumigation, in coincidence with the decrease in the frequency of live larvae (p ＜ 0.01) from sampling nets. Cage experiments showed significant differences (p ＜ 0.01) in anuran larvae survival before and after fumigations. Laboratory acute toxicity tests with endosulphan formulation demonstrated sublethal symptoms in Hypsiboas pulchellus larvae 24 h after initial exposure time. The 96 h LC-50 was 0.13 μg endosulphan/litre, which is over 1000 times lower than the cypermethrin LC-50 value. Endosulphan seems to be the insecticide responsible for the drastic effects on anuran larvae detected in the field during studied events.