Detritus-microbe interactions are essential for mosquito growth in natural settings

Mosquitoes like Aedes aegypti vector several pathogens of humans because adult females must blood feed to produce eggs. In contrast, most mosquito larvae are aquatic detritivores. Commensal microbes consisting primarily of bacteria continuously cycle between the larval gut and aquatic environment when larvae feed. Previous studies also show that larvae are unable to grow under normal rearing conditions when these commensal microbes are absent. However, whether larvae depend on specific microbes for growth when fed natural detritus diets is unknown. In this study, we show that detritus collected from several field sites enable Ae. aegypti larvae to develop into adults, whereas larvae do not grow when the microbes associated with each detritus sample are absent. Screening of these microbial communities indicated that successful development depends on particular bacteria. Several communities further enabled larvae to develop when fed sterile detritus diets collected from different locations. Our results overall suggest that detritus primarily serves as a resource for growth of microbes that Ae. aegypti larvae require for development. These findings also have implications for how microbes required by larvae affect adult traits that influence pathogen transmission to humans.