ACUTE TOXICITY AND SUBLETHAL EFFECT OF CARBARYL ON BIOCHEMICAL RESPONSES OF INDIAN EARTHWORM Lampito mauritii (KINBERG)

Application of many numbers of insecticides in the agricultural field has also threatened the soil beneficial organisms. Earthworms are one of the major soil biota. Carbaryl was commonly used insecticides against various insects in South India. Hence in present study was aimed to estimate acute toxicity and sublethal effect of carbaryl on biochemical responses of the L. mauritii. For acute toxicity study, mortality of earthworms was noted on 24, 48, 72, 96 and 120 h after exposure to various carbaryl concentrations. From the study, sublethal concentrations of carbaryl (T1- 4.195 ppm and T2-13.984 ppm) was selected and estimated activities of following enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and acetyl cholinesterase (AChE). The lipid peroxides (LP) and glutathione levels (GSH) were also determined. The GSH, SOD, CAT, GST and AChE activities decreased than the control upto 15 days, thereafter slightly increased on the day 30. High level of LP and GSH were observed until 15 days and on 30th day they were decreased. The results suggested that carbaryl highly inhibited the normal biochemical responses of earthworm upto 15 days due to the presence of carbaryl residues in the soil substrate as well as body of earthworm. By the microbial degradation of carbaryl, recovery was observed on the 30th day of experiment.