The mosquito microbiota largely impacts the propension of its host to transmit viruses and parasites, as it directly affects the development of these human pathogens in the mosquito and indirectly influence mosquito fitness. As such, it received much interest in the last decade as it may be used or targeted in the design of novel transmission blocking approaches. Studies based on antibiotic treatments or on feeding with diverse bacteria have shown that the effect of the microbiota on the mosquito is highly composition-dependent, hence it is important to take this parameter into account in functional studies. This may be addressed by combining sequencing analyses and experiments on a diversity of isolates.

Here, we introduce our efforts in establishing a library of bacteria isolated from multiple species of mosquitoes collected in several localities of French Guiana. We isolated 520 bacterial strains belonging to 34 families, including 45% isolates from five main families (Enterobacteriaceae, Bacillaceae, Acetobacteraceae, Pseudomonadaceae and Staphylococcaceae). We first characterized our bacteria in vitro, via metabolic analyses, including determination of their hemolytic and proteolytic activities, as these characteristics may affect digestion and gut permeability to pathogens.

Our data show that 45% of our isolates are hemolytic and 14% are proteolytic. We are currently studying the impact of our bacteria on mosquito fitness, focusing on smaller subsets of the library. This includes analyses on larval development, adult lifespan, blood feeding and reproduction. Some bacteria are beneficial to the mosquito's fitness while others are completely lethal to both larvae and adults.

After finalizing this characterization, we plan to share bacteria of our biobank as tools to study insect-microbe interactions. We also plan to select isolates to study their potential biopesticide activity and their impact on Ae. aegypti competence to dengue virus.