Environmental microplastics: sources, environmental interactions, ecotoxicological effects and plastivore-mediated biodegradation

Microplastics (MPs), as emerging pollutants, are potentially ingested by animals in aquatic and terrestrial environments, causing physical harm. The most widely produced synthetic polymers worldwide are polystyrene (PS), polyvinyl chloride (PVC), polyester (PET), polyethene (PE), polyamide (PA), and polypropylene (PP). To reduce microplastic density in the environment, studies evaluate the rate of MP ingestion by insect larvae. The larvae of insect orders Lepidoptera and Coleoptera are widely studied regarding MPs degradation. Additionally, the effect of MPs on insect physiology can be evaluated to further study their impact on human health. The review article focuses on the effect of MPs on growth, gut microbiota, and fertility of both aquatic and terrestrial insects. The paper also deals with widely researched ‘plastivore’ insects and the underlying mechanism of biodegradation and mineralisation of various forms of MPs by these insects. The structural resemblance of synthetic polymers to insect feed makes insects potential degraders of MPs. The change in abundance and type of gut microbiota in MPs-fed insect larvae compared to control larvae implies the significant role of gut microbiota and gut enzymes in MPs biodegradation. Microplastics as a novel feed substrate for plastivore insects.