Effects of acute insecticide exposures on Pomacea canaliculata

Abstract

The fresh water snail, Pomacea canaliculata, has particularities that makes it a potential good bioindicator. This species is affected by agrochemicals that can induce physiological and histopathological changes that have the potential to be characterized and could be used as biomarkers of freshwater contamination. In this study we a) identify the LC50 and NOECL at 48 hours of exposure to the insecticides Deltamethrin (Decis forte® 10.5%), Chlorfenapir (Onfire® 24%) and Lambdacialothrin (Rafter® 5%); b) evaluate changes in the activity of antioxidant enzymes in the digestive gland after an acute exposure to NOECL of these compounds, c) characterize whether exposure to these insecticides induces histological alterations in the digestive gland or in the presence of a symbiotic cyanobacterium that lives there. Adult animals (4 and 5 months) of both sexes cultured under laboratory conditions were used. Exposures of 48 hours to NOECL doses were carried out in four experimental groups from which tissues samples were taken for protein extraction, evaluation of superoxide dismutase (SOD) and catalase (CAT) activities and for histological processing and subsequent morphometric analysis (Image ProPlus®), respectively. LC50 (48h) and NOECL (48h) for Deltamethrin were 0.88 and 1.22 µg/mL, for Chlorfenapir were 2.85 and 1.00 µg/mL and for Lambdacialothrin 0.74 and 0.67 µg/mL. Acute exposure to insecticides produced a significant increase in SOD activity and also a significant decrease in CAT activity in Deltamethrin exposed animals (ANOVA I, Tukey post test). Likewise, the occupation of the glandular acini by symbiotic cyanobacteria was significantly decreased also in animals exposed to Deltamethrin (ANOVA I, Tukey post test). These results open the possibility of using P. canaliculata anatomical-physiological parameters as biomarkers of water contamination by insecticidal agrochemicals like Deltamethrin, and future studies evaluating the activity of other antioxidant enzymes and morphological alterations in other tissues will complete their characterization.