High-concentration polyethylene and polystyrene microplastics co-exposure shorten insect lifespan and impose...

Microplastics (MPs) are pervasive environmental pollutants, accumulating in ecosystems and posing a long-term exposure risk to both the entire ecosystem and human health. However, the combined impact of such high doses on insect longevity and the consequent ecological consequences remain understudied. Here we used Drosophila melanogaster as a model to quantify lifespan shortening under environmentally realistic and extreme concentrations of Polyethylene (PE) and Polystyrene (PS) co-exposures and to unravel the molecular bases of the observed toxicity. Furthermore, we delved into the underlying mechanism through metabolomics and transcriptomics analysis. Our results demonstrated PE and PS MPs co-exposure with greatly high concentrations significantly reduced the lifespan of Drosophila and influenced age-related phenotypes such as climbing ability, intestinal barrier and hunger resistance. We found that differential metabolites were engaged in various metabolic pathways, including ABC transporters, alanine, aspartate and glutamate metabolism. Differentially expressed genes (DEGs) were closely related to Toll and Imd signaling pathway and Longevity regulating pathway. Gram-level PE and PS co-exposure triggers immune-metabolic crosstalk failure and represents a realistic terrestrial risk factor for insect longevity. Our data highlight the urgent need to include high-dose microplastic mixtures in terrestrial ecotoxicological risk assessments and biodiversity conservation strategies. SYNOPSIS: Co-exposure to PE and PS MPs with high concentrations induces changes in gene expression and metabolites associated with immune system and energy metabolism in Drosophila, thereby affecting their lifespan.