Biochemical responses of earthworm (Eisenia foetida) to the pesticides chlorpyrifos and fenvalerate.

The effects of chlorpyrifos and fenvalerate on the activity of the cellulase, superoxide dismutase (SOD) and catalase (CAT) of the earthworm (Eisenia foetida) were studied. Earthworms were exposed to chlorpyrifos and fenvalerate at a final concentration of 10, 20, and 40 mg/kg dry soil, respectively. Tissues from each treatment were collected on days 1, 3, 5, and 7. Compared to the controls, the cellulase activity of E. foetida was inhibited by treatments with chlorpyrifos and fenvalerate. The SOD activity of earthworms exposed to chlorpyrifos was significantly inhibited compared to the control after 1 day of incubation, whereas SOD activity increased on day 3. As exposure to the pesticide progressed, the SOD activity recovered from the stimulative effect and reached the level of the control. The SOD activity of E. foetida in the presence of fenvalerate stress was significantly inhibited at the initial stage of exposure and increased after day 3, whereas the SOD activity continued to decrease in response to increasing exposure to fenvalerate. The CAT activity of E. foetida during pesticide stress first increased and then decreased, after day 5, compared to the controls. Alterations of the enzyme activity under environmental stresses are suggested as indicators of biotic and abiotic stress.