The midgut of Aedes albopictus shapes its bacteriome but not its mycobiome

Midgut microbiota consists mainly of bacteria and fungi and can interact directly or indirectly with ingested pathogens. However, both the specific microbes that stably colonize the mosquito midgut and how the midgut shapes their microbiome remain poorly understood. In this study, we analyzed the midgut microbiome of the insect vector Aedes albopictus at three different developmental stages collected from the field. Additionally, we reared field-collected larvae under laboratory conditions, using either field water from the breeding habitat or sterilized water, to track the linear evolution of the microbiome from larvae to adulthood.

Our metagenomic analysis revealed that the mosquito host selected specific bacterial species, while the mycobiome remained virtually identical to that of the surrounding water. We identified 42 core bacterial species that form a highly interactive network, as well as two core fungal species, both of which were consistently more abundant in the mosquito gut than in the surrounding water across all life stages in both laboratory and field conditions. Furthermore, we successfully assembled 271 bacterial genomes de novo, 14 of which belonged to core species. These 14 bacterial genomes were enriched in genes associated with antioxidant function and cAMP metabolism.

This study uncovers fluctuating bacterial dynamics alongside conserved fungal communities in the mosquito gut, suggesting distinct mechanisms that shape the bacteriome and mycobiome. This study highlights the antioxidant function in stabilizing bacteria in Aedes albopictus. © 2026 Society of Chemical Industry.