Microplastic ingestion perturbs the microbiome of Aedes albopictus (Diptera: Culicidae) and Aedes aegypti

Abstract

Microplastics (MPs) are common environmental pollutants; however, little is known about their effects after ingestion by insects. Here we fed Aedes (Stegomyia) aegypti (L.) and Aedes (Stegomyia) albopictus (Skuse) mosquito larvae 1 µm polystyrene MPs and examined the impacts of ingestion on adult emergence rates, gut damage, and fungal and bacterial microbiota. Results show that MPs accumulate in the larval guts, resulting in gut damage. However, little impact on adult emergence rates was observed. MPs are also found in adult guts postemergence from the pupal stage, and adults expel MPs in their frass after obtaining sugar meals. Moreover, MPs effects on insect microbiomes need to be better defined. To address this knowledge gap, we investigated the relationship between MP ingestion and the microbial communities in Ae. albopictus and Ae. aegypti. The microbiota composition was altered by the ingestion of increasing concentrations of MPs. Amplicon sequence variants (ASVs) that contributed to differences in the bacterial and fungal microbiota composition between MP treatments were from the genera Elizabethkingia and Aspergillus, respectively. Furthermore, a decrease in the alpha diversity of the fungal and bacterial microbiota was observed in treatments where larvae ingested MPs. These results highlight the potential for the bacterial and fungal constituents in the mosquito microbiome to respond differently to the ingestion of MPs. Based on our findings and the effects of MP ingestion on the mosquito host micro- and mycobiome, MP pollution could impact the vector competence of important mosquito-transmitted viruses and parasites that cause human and animal diseases.

A perspective on the impacts of microplastics on mosquito biology and their vectorial capacity

“…aegypti and Ae. albopictus larvae to 100–100,000 1 μm polystyrene MPs had little effect on adult emergence rates (Edwards et al, 2023). On exposure to mixed size classes (1–53 μm) of polyethylene MPs (60 MP mL −1 ), mortality was observed for Ae.…”

“…aegypti and Ae. albopictus following exposure to 1‐μm fluorescent polystyrene beads with MPs excreted in the frass of sugar‐fed adult Aedes mosquitoes (Edwards et al, 2023). By contrast, no ontogenic transfer of polyethylene MPs to pupae or adults was observed following exposure of first instar larvae (Griffin et al, 2023).…”

“…aegypti and Ae. albopictus perturbed the gut microbiome and mycobiome (Edwards et al, 2023). This lends support to the hypothesis that MP consumption causes damage to the gut epithelial tissue in mosquitoes, potentially allowing for systemic infection of gut bacteria in other mosquito tissues, although it is not clear whether there are carryover effects from larvae to adults.…”

“…No impact on emergence rates were observed in Aedes sp. exposed to 100–100,000 MPs/mL (Edwards et al, 2023) and water treated with 100 MP/mL did not affect Culex pipiens (Linnaeus) oviposition (Cuthbert et al, 2019). In similar experiments, no effect on survival rate ( p ) were observed in Culex sp.…”