Oxidaitve Stress And DNA Damage Induced By Imidacloprid Exposure In Earthworm

The invention of neonicotinoid insecticides is the landmark in the history of chemical in-secticide development. It was reported that the neonicotinoid insecticides had a turnover arou-nd$1560million and accounted for some17percents of the world’s annual sales of chemicalinsecticide in2006. Imidacloprid was the supreme exponent of the neonicotinoid insecticides.For it was widely used, imidacloprid had became the most popular and most effectiveinsecticide in the world. Imidacloprid was used to control sucking mouth parts insects, andonce the insects touched the insecticide, they would die.With the popular use of the imidacloprid, more and more imidacloprid will enter into theenvironment, damage the non-target organisms and influent the structure and function of eco-system. So it is important to research the toxicity of imidacloprid in non-target organisms to e-valuate its environmental safety.To investigate the soil ecological environment effect of imidacloprid, the present studywas operated with imidacloprid on the earthworm. Earthworms were exposed to a control andthree concentrations of imidacloprid (0.10,0.50, and1.00mg/kg soil) respectively and werestudied after7,14,21, and28days. The present study was conducted to investigate the effectof imidacloprid on ROS generation, antioxidant enzymes (SOD and CAT), GST activity,MDA content and the DNA damage of the earthworm. The main results are showed asfollows:(1)The ROS levels was increased, then decreased to control levels gradually andincreased again at last after exposure to imidacloprid with time. ROS generation wasincreased obviously after exposure to imidacloprid.(2)The SOD activity was significantly activated after exposure to imidacloprid; however,the CAT activity of all the concentrations was significantly inhibited after exposure toimidacloprid. The CAT activity and the concentration submitted a dose-effect relationship.(3)The GST activity was significantly induced after exposure to imidacloprid.(4)The MDA contents in most of treatment groups were significantly increased, and thechanges showed that imidacloprid could lead to earthworm’ injury of lipid peroxidation.(5)The result of Single Cell gel electrophoreses test showed that Olive tail moments ofearthworm coelomocytes were decreased gradually with increasing imidaclopridconcentrations and time. Imidacloprid could cause DNA damage of earthworm and DNAcross-linking was produced after exposure to high concentrations.