Bacterial midgut microbiota associated with mosquito populations in waste tires from two spatially segregated study sites in Urbana, Illinois

An improved understanding of mosquito-microbe interactions may inform the development of novel strategies for mosquito vector control. We used culture-dependent and culture-independent techniques to characterize the bacterial composition and abundance in water and midgut samples of larval and adult females of Aedes japonicus, Ae. triseriatus and Culex restuans collected from discarded tires at Trelease Woods and South Farms study sites in Urbana, Illinois. The phylum specific qPCR assay revealed that water samples and larval midguts from both study sites had a higher proportion of actinobacteria and a lower proportion of bacteroidetes than adult female midguts. Discriminant function (DF) analysis identified two bacterial taxa (a-proteobacteria and b-proteobacteria) from first DF and three taxa (g-proteobacteria, actinobacteria and firmicutes) from second DF as significant in defining the water samples and the midguts of larval and adult mosquitoes in both study sites. Only 14 out of the 56 bacterial species identified in this study occurred in both study sites. For both study sites, the number of bacterial species was highest in water samples (27 species from Trelease Woods; 25 species from South Farms), intermediate in larval midguts (12 species from Ae. japonicus; 11 species from Ae. triseriatus; 9 species from Cx. restuans) and lowest in adult female midguts (3 species from Ae. japonicus; 2 species from Ae. triseriatus). These findings suggest that the composition and richness of bacterial communities varies among habitats and mosquito species and that bacteria diversity in newly emerged adult mosquitoes is generally low likely due to gut renewal during metamorphosis.