Characterization of bacterial communities in host-seeking Anopheles arabiensis displaying attraction to human or cattle hosts under field conditions

Mosquito behavior is a major aspect of vector ecology. Their host seeking is tightly linked to their capacity to interact with different hosts and act as vectors of etiological agents. Evidence suggests that host seeking is determined by genetic factors, such as olfactory genes re-arrangements. Simultaneously, mosquito-associated microbiota is increasingly recognized as a particularly sensitive descriptor of ecological variation. In this study, we investigated microbial communities of host-seeking females of the malaria vector, Anopheles arabiensis, linked to their host preference, and whether mosquitoes attracted to the same host display more similar microbiota profiles. Beta-diversity analysis showed no clear clustering of microbial communities by host choice, collection site, or time of collection. However, alpha-diversity measures revealed that cattle-seeking mosquitoes from one of the two villages consistently displayed higher richness and evenness than human-seeking ones. This difference was associated with the presence of several unique taxa, suggesting that environmental factors, such as livestock abundance, can shape microbial profiles of adult host-seeking mosquitoes. We hypothesize a possible mechanism to explain our observations, namely that repeated feeding on cattle increases exposure to a broader microbial reservoir, which may be transiently acquired at first and their presence be reinforced through processes, such as accumulation in breeding habitats. Overall, our findings highlight, consistently with existing literature, that mosquito microbiota is structured by a hierarchy of influences. Conserved core taxa, and localized and specific environmental-related factors all converge into creating microbial communities, which carry traces of the recent life-history of a whole mosquito population.