UC Riverside

Mosquitoes are important vectors of many devastating human diseases. Much of the research to date has focused on their adult biology as vectors, but the field of microbiome research is rapidly developing. Commensal and symbiotic bacteria may play important roles in nutrition, digestion, or chemical defense for mosquitoes. The effects of larval mosquito presence and nutrient input on aquatic and larval mosquito microbiomes and on ecosystem structure and function were studied in 1 m2 mesocosms. Three levels of enrichment with organic and inorganic nutrients were cross-classified with larval mosquito presence or absence. Water quality variables (total nitrogen, nitrates, nitrites, ammonium, total phosphorous, and chemical oxygen demand), mosquito oviposition rates, invertebrate abundance, phytoplankton biomass, planktonic particle size spectra, primary production, community metabolism, and microbial diversity were measured during the 1-month study. The oviposition rate of Culex mosquitoes was directly related to nutrient enrichment. Mosquito presence significantly influenced phosphorus concentration, but did not significantly affect the concentration of other water quality variables. The presence of larval mosquitoes with high levels of nutrient input increased the photosynthetic productivity of aquatic mesocosms, with a corresponding decrease in bacterial diversity. Conversely, when mosquitoes were prevented from ovipositing in mesocosms, water column bacterial diversity increased at high levels of nutrients. This work shows that larval mosquitoes have profound impacts on aquatic ecosystems, especially when those ecosystems are affected by high nutrient input.