Toxicological study of two novel pesticides on earthworm Eisenia foetida

In this paper, several studies were conducted to evaluate the toxicity of t wo pesticides, Imidacloprid and RH-5849 on earthworm (Eisenia foetida) in t erms of their acute toxicity, biochemical toxicity and effects on sperm mor phological deformity. LC50 for earthworms indicated that these two pesticid es had different effects in different exposure systems. The results of bioc hemical 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 prom otion to a certain degree, except that lower concentrations of Imidacloprid (0.1 mg/l) could suppress SOD activity. In this study, sperm deformity tes t 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 displaye d when Imidacloprid concentrations higher than 0.5 mg/kg dry soil. However, the sperm deformity frequency of RH-5849-exposed groups did not show signi ficant difference (p>0.05) from the control until the dose reached 100mg/kg dry soil. (C) 1999 Elsevier Science Ltd. All rights reserved.