Mosquito-associated bacterial communities source from diet and environmental substrates

Abstract

Symbiotic microorganisms are often critical for metazoan host biological functioning. Over life stages, hosts acquire symbionts from their environment, though the specific environmental sources of microbial symbionts in hosts remain largely understudied. Moreover, patterns of microbial community assembly from these environmental sources are inadequately described. Here, we utilize two mosquito species of public health and conservation concern in Hawaiʻi to test the hypothesis that host microbiomes are composed of subsets of microbes from a high diversity microbial community in the environment, and that hosts acquire these microbial symbionts through their diet. We also experimentally test the effects of the microbial environment and diet on mosquito microbiome assembly. Our field results demonstrate nestedness of mosquito symbionts within the microbial community of the mosquito diet and free-living environmental substrates. We observed partitioning of microbiome composition by host status, in which microbiome compositions are more similar between plant and animal hosts in contrast to free-living environmental substrates. Additionally, our laboratory experiment showed the re-establishment of several naturally-occurring symbiont taxa in lab-reared mosquitoes with exposure to microbial-rich natural substrates, as well as significant interaction effects of microbial source pools from larval rearing environment and adult nutritional resources on microbiome composition. Our results have implications toward understanding the microbial community assemblage and environmental sources of symbionts, which can not only answer fundamental questions related to the diversity of the host microbiome, but can also help to inform mosquito management to augment human health and conservation efforts.