Ranjana S. Chavan, Akshay S. Pawar, Ruddhi R. Jagtap and Gajanan V. Mali
Abstract
The widespread use of pesticides in contemporary agriculture has created considerable concerns about their persistence in the environment and hazardous effects on non-target organisms. The current study examines the toxicity of earthworms (Lumbricus terrestris), which are significant bioindicators of soil health, to the synthetic pyrethroid pesticide fenvalerate and the byproducts of its microbial breakdown. Brevibacillus brevis RCGM1, a recently identified bacterial strain, biodegraded fenvalerate, and the toxicity of the parent substance and its metabolites was assessed using 48-hour contact filter paper tests and 14-day soil exposure testing. The findings showed that fenvalerate was more hazardous than its metabolites, having LC50 values of 7 ppm and 30 ppm, respectively. In both experimental circumstances, earthworm mortality rose as concentrations increased. Histopathological examination revealed substantial damage to the intestinal tissues in fenvalerate-treated earthworms, including disruption of circular and longitudinal muscles, tissue erosion, and loss of structural integrity, whereas metabolite-treated worms showed minor changes. These results show that the toxicity of fenvalerate is greatly reduced by microbial breakdown. The study highlights the use of earthworms as sensitive bioindicators for environmental risk assessment and the promise of microbial bioremediation as an ecologically friendly method for reducing pesticide pollution.