Polyvinylchloride and polypropylene as adsorbents of the pesticide monocrotophos enhance oxidative stress in Eudrillus eugeniae (Kinberg)

The use of plastics has increased significantly with consequent rise in the generation of wastes. Microplastics (MPs) with particle size <5 mm are produced in natural terrestrial habitats by weathering of the discarded plastic debris and therefore are likely to impact soil biota. Earthworms are the dominant soil fauna which play vital role in soil formation and decomposition of organics. Since these animals are soil feeders, MP particles contaminating soil are likely to enter in to the gut of these animals affecting their physiology. MPs have been shown to be potent adsorbents of various other pollutants such as heavy metals and agrochemicals. This study reports the effects of two MPs, polyvinyl chloride (PVC) and polypropylene (PP) alone and in combination with the pesticide monocrotophos in soil on tissue protein, lipid peroxidation (LPX), activities of lactate dehydrogenase (LDH) and catalase (CAT) of an epigeic earthworm Eudrillus eugeniae over an exposure period of 48h. Results from molecular docking and laboratory experiment confirmed that both the MPs are potent adsorbents of the pesticide and enhanced oxidative stress on the animal with significant reduction in protein, increased LPX level and enzyme activities. PP indicated significantly higher pesticide adsorption relative to PVC.