Microplastic pollution differentially affects development of disease-vectoring Aedes and Culex mosquitoes.

Plastic in the form of microplastic particles (MPs) is now recognized as a major pollutant of unknown consequences in aquatic habitats. Mosquitoes, with aquatic eggs, larvae, and pupae, are likely to encounter microplastic, particularly those species that are abundant in close proximity to human development, including those that vector human and animal disease. We examined the effects of polyethylene MPs, the most common microplastic documented in environmental samples, on the development and survival of the mosquitoes Aedes albopictus and Culex quinquefasciatus. In laboratory egg-laying and larval development container environments similar to those used by both species in the field, a mix of 1-53 µm MPs at concentrations of 60, 600, and 6000 MP ml-1 increased early instar larval mortality in both species relative to control treatments. A significant difference was found in the response of each species to microplastic at the lowest microplastic concentration tested, with Cx. quinquefasciatus survival equivalent to that in control conditions but with Ae. albopictus larvae mortality elevated to 37% within 48 h. These results differ from those of previous studies in which larvae were only exposed to MPs during the last aquatic instar stage and from which it was concluded that microplastic was ontogenically transferred without negatively affecting development. Increasing plastic pollutant concentrations could therefore act as selective pressures on aquatic larvae and ultimately influence outcomes of ecological interactions among mosquito vector populations.

Filtration of environmentally sourced aquatic media impacts laboratory-colonised Aedes albopictus early development and adult bacteriome composition.

Microorganisms form close associations with metazoan hosts forming symbiotic communities, known as microbiomes, that modulate host physiological processes. Mosquitoes are of special interest in exploring microbe-modulated host processes due to their oversized impact on human health. However, most mosquito work is done under controlled laboratory conditions where natural microbiomes are not present and inferences from these studies may not extend to natural populations. Here we attempt to assemble a wild-resembling bacteriome under laboratory conditions in an established laboratory colony of Aedes albopictus using aquatic media from environmentally-exposed and differentially filtered larval habitats. While we did not successfully replicate a wild bacteriome using these filtrations, we show that these manipulations alter the bacteriomes of mosquitoes, generating a unique composition not seen in wild populations collected from and near our source water or in our laboratory colony. We also demonstrate that our filtration regimens impact larval development times, as well as impact adult survival on different carbohydrate diets.