Biochemical and physiological responses in Caenorhabditis elegans exposed to sublethal concentrations of the organophosphorus insecticide, monocrotophos

• Sublethal concentrations of monocrotophos elicits toxicity in Caenorhabditis elegans.
• MCP induces paralysis and reduction in brood size in the worms.
• AChE and CaE are significantly inhibited on MCP exposure.
• MCP exposure induces oxidative stress in the worms.

The objective of this study was to investigate the impact of sublethal concentrations of MCP on definitive markers of toxicity and oxidative balance in the nematode, Caenorhabditis elegans. Exposure of worms to 0.85, 1.7 and 3.4 mM (1/40, 1/20 and 1/10 LC50; LC50=34 mM) for 4 h at 20 °C induced significant perturbations in physiological parameters such as decreased brood size (47–73%), increased paralysis (47–85%) and inhibition of the activities of acetylcholinesterase (75–86%) and carboxylesterase (76–81%). These changes were accompanied by distinct oxidative impairments as evidenced by increased reactive oxygen species, decline in glutathione content and decrease in superoxide dismutase activity. Our results clearly demonstrate that low concentrations of MCP may alter the physiological and biochemical status in the nematode, thereby affecting the organism's fitness. Our findings on C. elegans provide an easy diagnosis for OPI contamination and may become helpful in evaluating the ecotoxicological effects of OPI in the aquatic environment near agricultural fields.

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