Oxidative stress and gene expression of earthworm (Eisenia fetida) to clothianidin

Neonicotinoid insecticides have become the most widely used pesticides in the world. Clothianidin is a novel neonicotinoid insecticide with a thiazolyl ring that exhibits excellent biological efficacy against a variety of pests. In the present study, the oxidative stress and genotoxicity of clothianidin on earthworms were evaluated. Moreover, the effective concentrations of clothianidin in artificial soil were monitored during the whole exposure period. The results showed that clothianidin was stable in artificial soil and that the residue concentrations were 0.094, 0.476, and 0.941 mg/kg after 28 d of exposure, which represented changes no more than 10% compared to the concentrations on the 0th day. Additionally, both the concentration of and exposure time to clothianidin had a substantial influence on biomarkers in earthworms. At 0.5 mg/kg and 1.0 mg/kg, the reactive oxygen species (ROS) levels were greatly enhanced, causing changes in antioxidant enzyme activities, damage to biological macromolecules and abnormal expression of functional genes. Additionally, the present results showed that superoxide dismutase (SOD), DNA damage and heat shock protein 70 (HSP70) may be good indicators for environmental risk assessment of clothianidin to earthworms.