Inhibition and recovery of molecular biomarkers of earthworm Eisenia andrei after exposure to organophosphate dimethoate

Abstract

Dimethoate is a broad-spectrum organophosphorous insecticide produced and used in many countries against a wide range of pests. Like other pesticides, dimethoate also affects many non-target organisms, including soil organisms. In this study for the first time effects of dimethoate on molecular biomarkers (AChE, CES, CAT and GST activity, concentration of GSH and efflux pump activity) of Eisenia andrei earthworms were evaluated using the artificial OECD soil. Earthworms were exposed to environmentally relevant doses of dimethoate (0.03, 0.1, 0.3, 1 and 3 mg/kg) for 1, 3, 6, 10, 15, 21 and 28 days and besides the time-related responses of biomarkers, the recovery of AChE, CES and CAT activity was also investigated. Results showed that dimethoate caused dose dependent significant changes in measured biomarkers – inhibition of AChE, CES and CAT activity; increase in GST activity and concentration of GSH; and both induction and inhibition of efflux pump activity. Additionally, the selected molecular biomarkers showed slow recovery rate and at the highest applied concentration of dimethoate, the inhibition of enzymes was evident even after 28 days of recovery. The obtained results indicate that application of dimethoate in agriculture could have harmful effects on earthworms since application of environmentally relevant doses, i.e. doses that are applied in agriculture, caused significant changes in measured biomarkers.