Project Summary: Mosquitoes transmit multiple diseases worldwide accounting for millions of disease cases and hundreds of thousands of deaths each year. The United States is not immune to the scourge of mosquito-borne disease, as mosquitoes in the USA can transmit dengue and Zika viruses as well as West Nile and La Crosse encephalitis virus. Mosquitoes are also a substantial nuisance that reduce quality of life and enjoyment of outdoor activity. Control of mosquito populations is the primary way we prevent disease transmission and nuisance issues. Many new methods of mosquito population reduction involve a modified version of a method called sterile insect technique (SIT) in which males are made reproductively sterile in a laboratory and released to mate with wild females. This results in zero offspring and a reduction in the population of that targeted mosquito species. SIT requires mass rearing of male mosquitoes in large rearing facilities and these males must be healthy and able to compete with wild males for mates. Here, we propose to investigate the potential impact the mosquito bacterial microbiota (i.e. bacteria in the mosquito body) may have on male Aedes aegypti mosquito traits that are relevant for SIT including longevity, body size, and ability to compete for mates. We will also investigate the way the microbiota affects the transcriptome of males. This work will be the first in-depth investigation into the role of the microbiota in male mosquito fitness traits and will provide key insight into ways the microbiota might be leveraged to improve SIT for mosquito control.