Oxidative stress of imidaclothiz on earthworm Eisenia fetida

Imidaclothiz, a kind of neonicotinoid insecticides, is developed as a commercial pesticide in China and used for the control of sucking and biting insects, including aphids, whiteflies, beetles and some Lepidoptera species as well. In recent years, more and more attention has been focused on the adverse effects of neonicotinoid insecticides on non-target organisms. In this study, inhibition effects of imidaclothiz and recovery capacity of molecular biomarkers (GST, CE, CAT, SOD and POD activity, and DNA damage) in earthworms were detected for the first time. Earthworms were exposed to imidaclothiz (0.3 and 1.0mgkg^-1) for 28days, and then transferred to the clean artificial soil for 28days. Regarding enzyme activities, GST, CE, CAT and POD were inhibited following exposure to imidaclothiz at one or more sample times, while SOD was not affected. After transferring to the clean artificial soil, POD continued to be significantly inhibited till sample time 35days at 0.3mg/kg^-1. For GST, CE, CAT and SOD, activities of them were significantly increased compared to those of the control during the recovery period. The olive tail moments (OTM) in comet assay, as an indication of DNA damage, were significantly increased compared to the control after treatment and then decreased during the recovery period. These results suggested that imidaclothiz induced oxidative damage on earthworms which caused damage to vital macromolecules including DNA. However, the recovery changes of all tested biomarkers following the transfer to clean soil suggested the tested earthworm recovery from imidaclothiz exposure.