Natural variation in physicochemical profiles and bacterial communities associated with Aedes aegypti breeding sites and larvae on Guadeloupe and French Guiana

Background: Immature stages of Aedes aegypti develop in many man-made aquatic habitats in which mosquito larvae are exposed to physicochemical elements and microorganisms that may influence their life cycle and their ability to transmit human arboviruses. Despite the omnipresence of Ae. aegypti in tropical and subtropical regions, little is known about the natural bacterial communities associated with this mosquito or their relation to the biotic and abiotic characteristics of their aquatic habitats. We comprehensively characterized the physicochemical properties and bacterial microbiome of Ae. aegypti breeding sites and larvae on Guadeloupe and in French Guiana. In addition, we explored whether geographical location, the type of breeding site and physicochemical parameters of the water influenced the microbiota associated with this mosquito species.Method: We used large-scale 16S rRNA gene sequencing of 160 breeding sites and 147 pools of Ae. aegypti larvae from sites widely distributed across Guadeloupe and French Guiana and recorded 13 physicochemical parameters at the sampled breeding sites. Ordination plots and multiple linear regression were used to assess the influence of environmental factors on the bacterial microbiome of water and larvae.Results: We found territory-specific differences in physicochemical properties (dissolved oxygen, conductivity and metal content) and the composition of bacterial communities in Ae. aegypti breeding sites that influenced the relative abundance of several bacteria genera (Methylobacterium, Roseoccocus) on the corresponding larvae. A significant fraction of the bacterial communities identified on Ae. aegypti larvae, dominated by Herbiconiux and Microvirga genera, were consistently enriched in mosquitoes regardless the location. Conclusion: Territory-specific differences observed in the biotic and abiotic properties of Ae. aegypti breeding sites influenced a fraction of the microbial communities of the corresponding larvae, raising concern about the impact of these changes on pathogen transmission by different Ae. aegypti populations.