Biological response of earthworm, Eisenia foetida (Savigny) to an organophosphorous pesticide, profenofos

Acute toxicity, morphological alterations and histological effects of an organophosphorus insecticide, profenofos (PFF) to earthworm, Eisenia foetida were evaluated by direct contact through a filter paper. The 24 and 48 h LC50 was 4.56 and 3.55 μg cm−2, respectively. Morphological and histological observations showed body ruptures, bloody lesions, and internal excessive formation of glandular cell mass and disintegration of circular and longitudinal muscles, which failed to regulate the internal coelomic pressure, leading to fragmentation in earthworms. Neurotoxic potentiality of PFF was assessed by measuring acetylcholinesterase (AChE). AChE basal Km and Vmax values were 0.26 mM and 0.15 μmol min−1 mg−1 protein, respectively. PFF alters the in vitro Km value, resulting in a competitive type of inhibition. The inhibitory constant Ki was 2.52×10−6 M. Morphological alterations and histological effects should be monitored in addition to AChE inhibition to assess OP pesticide contamination in soil ecosystems.