Microplastic effects on the Aedes albopictus and Aedes aegypti microbiome and host immunity

Plastic pollution remains one of the most ubiquitous and menacing ecological threats worldwide. Though larger plastics have been known to cause ecological impact, little is known about the effects of much smaller microplastics, which can be formed by the degradation of plastics by UV light and abrasion. Microplastics, defined by a size a few microns or less are difficult to remove from the environment and are easily ingested by animals, particularly invertebrates and their biological effects are unclear. While previous studies have focused on the ecotoxicology of microplastics on other insects and animals, no studies have examined the effects of microplastics on the microbiome, immunity, and ecology of container inhabiting mosquitoes, such as Aedes albopictus (Asian tiger mosquito) and Aedes aegypti (yellow fever mosquito). The goal of the studies was to examine how ingestion of microplastics as larvae will impact the composition of the microbiota of Ae. aegypti and Ae. albopictus and affect immune response. Fluorescent polystyrene beads of 1 µm diameter were fed to Ae. albopictus and Ae. aegypti larvae at varying concentrations, and 16s and ITS2 high through Illumina sequencing was used to identify changes in bacterial and fungal microbiome composition. Our results demonstrate that ingestion of microplastics results in dysbiosis of the bacterial microbiota but has little impact on the fungal microbiota composition in Ae. aegypti and Ae. albopictus. For immunity experiments, a concentration of 10,000 mp/mL of the fluorescent polystyrene beads of 1 µm diameter were fed to mosquito larvae and immune response was determined through real-time polymerase chain reaction (qPCR). Our results showed that microplastic indigestion as larvae did not have a significant impact on the immune response of the Toll and IMD pathway. Understanding the effects of microplastics on microbiota composition is crucial for predicting and effectively mitigating the potential effects of microplastics exposure in mosquitoes in relation to vector competence.

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