Differential Responses of Biochemical and Behavioral Parameters in the Native Gastropod Chilina gibbosa Exposed Subchronically to Environmental Concentrations of Two Insecticides Used in Argentina

Abstract

In this chapter, we show the results obtained after exposing the freshwater gastropod Chilina gibbosa 7 and 14 days to the organophosphate azinphos-methyl and the carbamate carbaryl. These insecticides are applied in Argentina and found in water bodies. Chilina gibbosa is naturally distributed in our country, and the family (Chilinidae) is considered vulnerable. It has an important role in the ecosystem being food of fishes and birds. After exposure to the same molar concentration of these insecticides, which corresponds to an environmental concentration in both cases, we registered lethality, neurotoxicity, and cholinesterase and carboxylesterase activities. Our results show that the subchronic exposure to an environmental concentration of azinphos-methyl caused severe signs of neurotoxicity (the abnormal exposure of the head-foot region and the loss of adherence) after 7 and 14 days of exposure. Cholinesterases were more sensitive than carboxylesterases. Inhibition of 89% of cholinesterase activity was observed after 7 days of exposure, while the decrease of carboxylesterase activity occurred after 14 days. Additionally, azinphos-methyl decreased protein content in C. gibbosa. On the other hand, the subchronic exposure to carbaryl only produced an inhibition of carboxylesterase activity measured with p-nitrophenyl butyrate as substrate. We conclude that insecticides applied in Argentina can cause toxic effects in the native gastropod C. gibbosa and that azinphos-methyl is more toxic than carbaryl. The presence of these insecticides in water bodies could put this species at risk, negatively disturbing the environment.