Supplementary material from "Partial consumption of medical face masks by a common beetle species"

The widespread distribution of microplastics (MPs) in the environment has motivated research on the ecological significance and fate of these pervasive particles. Recent studies have demonstrated that MPs may not always have negative effects and in contrast, several species of Tenebrionidae beetles utilized plastic as a food source in controlled laboratory experiments. However, most studies of plastic-eating insects have not been ecologically realistic, and thus it is unclear whether results from these experiments apply more broadly. Here we quantified the ability of mealworms (Coleoptera: Tenebrionidae) to consume MPs derived from polypropylene (PP) and polylactic acid (PLA) face masks; these are two of the most commonly used conventional and plant-based plastics. To simulate foraging in nature, we mixed MPs with wheat bran to create an environment where beetles were exposed to multiple food types. Mealworms consumed ~50% of the MPs, egested a small fraction, and consumption did not affect survival. This study adds to our limited knowledge of the ability of insects to consume MPs. Understory or ground-dwelling insects may hold the key to sustainable plastic disposal strategies, but we caution that research in this field needs to proceed concomitantly with reductions in plastic manufacturing.