Effect of the pesticide monocrotophos on the osmoregulation of a brackish water oligochaete, Pontodrilus bermudensis (beddard) in relation to salinity variations

Abstract

The toxicity of a commonly used organophosphate pesticide, Monocrotophos, on Pontodrilus bermudensis (Beddard) in optimum salinity was studied from a tropical brackish water environment, the Southern Lighter Channel at the Visakhapatnam Harbour. Physicochemical characteristics were determined at the habitat of the worm during the period of the study. The LC 50 values obtained for this worm subjected to 24, 48, 72 and 96 hours exposure showed that the toxicity of the pesticide increased with the period of exposure. The high LC 50 values indicated its endurance to the toxicant. The concentration changes found in the body fluid (C - , Na+ & K+) in the worms might suggest the possible influence of the pesticide on ion pumps or ion regulatory mechanisms of the worm. The present study confirms that Monocrotophos has interfered remarkably with ion regulation of the worm.