Mosquito Microbiome Dynamics, a Background for Prevalence and Seasonality of West Nile Virus

Symbiotic microbial communities augment host phenotype, including defense against pathogen carriage and infection. We sampled the microbial communities in 11 adult mosquito host species from six regions in southern Ontario, Canada over 3 years. Of the factors examined, we found that mosquito species was the largest driver of the microbiota, with remarkable phylosymbiosis between host and microbiota. Seasonal shifts of the microbiome were consistently repeated over the 3-year period, while region had little impact. Both host species and seasonal shifts in microbiota were associated with patterns of West Nile virus (WNV) in these mosquitoes. The highest prevalence of WNV, with a seasonal spike each year in August, was in the complex, and high WNV prevalence followed a decrease in relative abundance of in this species. Indeed, mean temperature, but not precipitation, was significantly correlated with abundance. This suggests that at higher temperatures abundance is reduced leading to greater susceptibility to WNV in the subsequent generation of hosts. Different mosquito genera harbored significantly different bacterial communities, and presence or abundance of was primarily associated with these differences. We identified several operational taxonomic units (OTUs) of that drive overall microbial community differentiation among mosquito taxa, locations and timepoints. Distinct OTUs were consistently found to dominate microbiomes of , and of . Seasonal fluctuations of several other microbial taxa included , and . This suggests that microbiota may explain some of the variation in vector competence previously attributed to local environmental processes, especially because is known to affect carriage of viral pathogens.