A biomarker assessment of pesticide toxicity in endemic, native peregrine, and invasive earthworm species from the Muthalamada mango plantations, Kerala, India

<p>This study assessed the toxic effects of pesticide exposure on four earthworm species: <em>Perionyx excavatus</em> Perrier, 1872; <em>Megascolex konkanensis</em> Fedarb, 1898; <em>Dichogaster affinis</em> (Michaelsen, 1890); and <em>Metaphire houlleti</em> (Perrier, 1872). The organisms were exposed to pesticide-treated soil. Biomass reduction, immunotoxicity, and enzyme biomarkers were used as endpoints. Among the tested species, <em>M. konkanensis</em>, a native species, appeared more sensitive than the others. In biomass tests, chlorpyrifos showed no significant effect on final body mass (p > 0.05). <em>P. excavatus</em> showed a significant reduction in body mass between 0.001 and 0.02 ppm of the pesticide mixture (p < 0.05), and exhibited avoidance behaviour. <em>M. konkanensis</em> showed avoidance at 0.02 ppm of the mixture but not at lower concentrations. Changes in AChE, LPO, GST, and CAT activities indicated pesticide-related stress. These results support the use of <em>P. excavatus</em>, <em>D. affinis</em>, and <em>M. houlleti</em> as indicators for soil contamination by pesticides.</p>