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Abstract BackgroundVector competence inAedes aegyptiis influenced by various factors. Crucial new control methods can be developed by recognizing which factors affect virus and mosquito interactions. MethodsIn the present study we used three geographically distinctAe. aegyptipopulations and compared their susceptibility to infection by dengue virus serotype 2 (DENV-2). To identify any differences among the three mosquito populations, we evaluated expression levels of immune-related genes and assessed the presence of microbiota that might contribute to the uniqueness in their vector competence. ResultsBased on the results from the DENV-2 competence study, we categorized the three geographically distinctAe. aegyptipopulations into a refractory population (Vilas do Atlântico), a susceptible population (Vero) and a susceptible but low transmission population (California). The immune-related transcripts were highly expressed in the California population but not in the refractory population. However, the Rel-1 gene was upregulated in the Vilas do Atlântico population following ingestion of a non-infectious blood meal, suggesting the gene’s involvement in non-viral responses, such as response to microbiota. Screening of the bacteria, fungi and flaviviruses revealed differences between populations, and any of these could be one of the factors that interfere with the vector competence. ConclusionsThe results reveal potential factors that might impact the virus and mosquito interaction, as well as influence theAe. aegyptirefractory phenotype. Graphical Abstract 

Abstract Insecticide resistance has emerged as a persistent threat to the fight against vector-borne diseases. We compared the gut microbiota of permethrin-selected (PS) strain ofAedes aegyptirelative to the parent (KW) strain from Key West, Florida. Bacterial richness but not diversity was significantly higher in PS strain compared to KW strain. The two mosquito strains also differed in their gut microbial composition.Cutibacteriumspp.,Corynebacteriumspp.,Citricoccusspp.,Leucobacterspp.,Acinetobacterspp.,Dietziaspp., andAnaerococcusspp. were more abundant in PS strain than in KW strain. In contrast,Sphingomonasspp.,Aquabacteriumspp.,Methylobacteriumspp.,Flavobacteriumspp.,Lactobacillusspp., unclassified Burkholderiaceae and unclassified Nostocaceae were more abundant in KW strain compared to PS strain. PS strain was enriched with propionate metabolizers, selenate reducers, and xylan, chitin, and chlorophenol degraders while KW strain was enriched with sulfur oxidizers, sulfur metabolizers, sulfate reducers and naphthalene and aromatic hydrocarbons degraders. These findings demonstrate an association between the gut microbiota and insecticide resistance in an important vector species and sets the foundation for future studies to investigate the contribution of gut microbiota to evolution of insecticide resistance in disease vectors.