Toxicological study of two novel pesticides on earthworm Eisenia foetida

In this paper, several studies were conducted to evaluate the toxicity of two pesticides, Imidacloprid and RH-5849 on earthworm (Eisenia foetida) in terms of their acute toxicity, biochemical toxicity and effects on sperm morphological deformity. LC50for earthworms indicated that these two pesticides had different effects in different exposure systems. The results of biochemical toxicity tests showed that lower concentrations of Imidacloprid (< 0.2mg/l) and RH-5849 (<25mg/l) could be observed to inhibit the activity of cellulase. As to the influence to SOD, they both expressed effects of promotion to a certain degree, except that lower concentrations of Imidacloprid (0.1 mg/l) could suppress SOD activity. In this study, sperm deformity test was developed to detect the potential adverse influences of pesticides on the reproduction of earthworms. The results demonstrated that significant induction of sperm deformity (p<0.01) and dose-effect relationship displayed when Imidacloprid concentrations higher than 0.5mg/kg dry soil. However, the sperm deformity frequency of RH-5849-exposed groups did not show significant difference (p>0.05) from the control until the dose reached 100mg/kg dry soil.