Toxicological Study of Bifenthrin and its Metabolites on Earthworm (Eisenia fetida)
2019
G. V. Mali
Pyrethroids are used in agricultural to control pests on a variety of crops. Bifenthrin, a synthetic pyrethroid, is a broad spectrum insecticide. It acts mainly on the nervous system of vertebrates as well as invertebrates. It is susceptible to the biodegradation by some soil bacteria. The present paper deals with the toxicological studies of bifenthrin and its metabolites benzene 1,1(methylthio) ethylidine, resorcinol and monochloro trifluromethane that were produced by a newly isolated strain of Paracoccus siganidrum APGM1 on earthworms, which play an important role in the improvement of the soil fertility. The toxicity was assessed by 48 hrs filter paper contact test, 14 days soil test and histopathological methods. The results of filter paper contact test revealed that the earthworms were more susceptible to bifenthrin than their metabolites. The LC50 value of bifenthrin and its metabolites was 6 ppm and 20 ppm respectively. The soil test showed that at 6 ppm concentration of bifenthrin, half the number of earthworms died after 14 days and with the increase in the concentration, mortality increased. At 10 ppm concentration, all the earthworms died. However, half the number of earthworms died after 14 days at the metabolite concentration of 20 ppm. The adverse effects of bifenthrin and very little effect of their metabolites on the morphological properties and structural integrity of the tissues were observed in histopathological studies. Thus, the metabolites of bifenthrin were less toxic to earthworms than the bifenthrin.
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