Inhibition and Restoration of Esterase Activity in Freshwater Snails after Exposure to the Pesticides; Profenofos, Carbofuran, and Thiamethoxam

Pesticides are important in farming operations as they ensure crop yields of high quality and quantity. Aerial drifts of these chemicals during spraying direct them to non-target aquatic reservoirs where they adversely affect aquatic fauna and flora. The recovery of aquatic snails Helisoma duryi from toxicological effects of exposure to pesticides was investigated. The snails were exposed to 0.5 ppb of profenofos, carbofuran and thiamethoxam for up to 28 days. Fifteen snails were removed from each exposure tanks on days 1, 14 and 28 and stored. After 28 days of exposure the remaining snails were transferred to pesticide-free water for an additional 28 days. On days 14 and 28, snails were sampled from each exposure tank and stored. Esterase activity was analysed in all samples. Inhibitions of esterase activities were observed in all pesticide-exposed snails. Carbofuran caused the highest inhibitions. Esterase activity returned to ≥ 90% of normal levels after 28 days of recovery in snails exposed to profenofos and thiamethoxam. The results of this study indicate that aquatic snails can recover from effects of pesticides exposure. Proper management and spacing of pesticide applications are suggested to protect the health of non-target aquatic organisms.