Dermal, histological anomalies with variations in enzyme activities of the earthworms Lampito mauritii and Drawida willsi after short term exposure to organophosphate pesticides

Monocrotophos and glyphosate are two potent organophosphate pesticides used on agricultural farms in India to control insect pests and weeds, respectively. Consistent application of these chemicals poses a risk of residual soil contamination with possible adverse implications on non-target organisms, like earthworms. The present study evaluates the impacts of these pesticides on the skin, muscles and certain biochemical parameters such as protein content, lipid peroxidation (LPX) level, activities of lactate dehydrogenase (LDH), acetylcholinesterase (AChE) and catalase (CAT) of two tropical earthworms Drawida willsi and Lampito mauritii. Monocrotophos at 1.0, 2.0, 3.0 g/kg soil and glyphosate at 0.1, 0.15, 0.2 g/kg soil were used for the experiment. At high concentrations, both pesticides induced lesions and skin undulation in the earthworms. In L. mauritii, the postclitellar region indicated muscle disorganization with high concentrations of monocrotophos. The lowest protein level was recorded in D.willsi and L. mauritii with high concentrations of monocrotophos. L. mauritii exhibited maximum LPX at high concentrations of glyphosate. Both the earthworms indicated the least LDH activity with high pesticide concentration. Minimal AChE activity in L. mauritii was observed with a high concentration of glyphosate. A high concentration of monocrotophos inhibited CAT activity in L. mauritii. The variable response of the selected morpho-histological and biochemical parameters in the earthworms to different pesticide concentrations could be useful early warning biomarkers to evaluate soil residual toxicity.