Acetylcholinesterase and Glutathione-S-Transferase as Biomarkers for Imidacloprid Toxicity in Earthworm Eudrilus eugeniae and Metaphire posthuma.

The present study investigated the effect of imidacloprid on the AChE and GST activity in earthworm Eudrilus eugeniae and Metaphire posthuma. E. eugeniae and M. posthuma were exposed to soil spiked with different concentrations (0.3, 0.6 and 1.0 mg/kg dry soil) of imidacloprid under laboratory conditions. The activity of AChE and GST have been reported as potential biomarkers to assess toxicity levels, hence the activity of these enzymes were assessed to study imidacloprid toxicity. Inhibition of AChE activity was observed in both the earthworm species in all the doses of imidacloprid, indicating neurotoxicity. There was an initial increase in the GST activity followed by its decrease with the duration of exposure to imidacloprid. Imidacloprid is highly toxic to earthworm inducing physiological which may cause catabolism of enzymes. Earthworm M. posthuma was observed to be more susceptible as compared to E. eugeniae. The current study signifies that the irrational use of such insecticides could pose high threat to non-target organisms, for example earthworms which play a key role in soil ecosystem productivity. [ABSTRACT FROM AUTHOR]