Predaceous Toxorhynchites mosquitoes require a living gut microbiota to develop

Most species of mosquitoes are detritivores that feed on decaying plant and animal materials in their aquatic environment. Studies of several detritivorous mosquito species indicate that they host relatively low diversity communities of microbes that are acquired from the environment while feeding. Our recent results also indicate that detritivorous species normally require a living gut microbiota to grow beyond the first instar. Less well known is that some mosquitoes, including those belonging to the genusToxorhynchites , are predators that feed on other species of mosquitoes and nektonic prey. In this study, we asked whether predaceousToxorhynchites amboinensis larvae still require living microbes in their gut in order to develop. Using the detritivorous mosquitoAedes aegypti as prey, we found thatT. amboinensis larvae harbour bacterial communities that are highly similar to that of their prey. Functional assays showed thatT. amboinensis first instars provided axenic (i.e. bacteria-free) prey failed to develop, while two bacterial species present in gnotobiotic (i.e. colonized by one or more known bacterial species) prey successfully colonized theT. amboinensis gut and rescued development. AxenicT. amboinensis larvae also displayed defects in growth consistent with previously identified roles for microbe-mediated gut hypoxia in nutrient acquisition and assimilation inA. aegypti. Collectively, these results support a conserved role for gut microbes in regulating the development of mosquitoes with different feeding strategies.