Biological effects of two insecticides on earthworms (Lumbricus terrestris L.) under laboratory conditions

Earthworms (Lumbricus terrestris L.) were exposed to endosulfan and aldicarb for 2, 7, and 15 days and lethal concentrations were determined. Worms were then exposed to these concentrations (LC10, LC25, and LC50) of endosulfan and (LC10 and LC25) of aldicarb. Growth rate, total protein content, and insecticide residues were determined. Aldicarb was more toxic than endosulfan and both insecticides caused a significant reduction of growth rate and total protein content of earthworms. Residues remaining in the soil after 2 to 15 days ranged between 37.75% and 68.54% of applied concentration for endosulfan and between 10.13% and 67.71% of applied concentration for aldicarb. Less than 1% of soil concentration was detected in worms and accumulation was more important in the case of endosulfan. This study proposes the use of growth rate and total protein content as biomarkers for contamination by endosulfan and aldicarb.