Senescent leaf exudate increases mosquito survival and microbial activity

We conducted experiments to evaluate the effects of soluble components in senescent leaf material on the growth and development of the eastern tree hole mosquito, Aedes triseriatus (Say). Oak leaves that were either leached for three days to remove the labile nutrient fraction, or were not leached, served as basal nutrient inputs in each experiment.Mosquito performance in microcosms containing leachate only was significantly worse compared with microcosms containing leaf material in combination with either leachate or water, indicating the importance of leaf substrates to mosquito production.Adult mosquito biomass, emergence, and development time were significantly higher in microcosms containing unleached leaves compared with leached leaf material. Additions of leachate to leached leaf treatments enhanced adult production, but not to the level observed in unleached leaf treatments.Filtered and unfiltered leachate added substantial nitrogen and phosphorus to microcosms and significantly affected mosquito growth responses. Bacterial productivity and abundance were also significantly affected by leachate additions and filtering.Taken together, these results suggest that while leaves decline with respect to nutritional value during decomposition, they remain important components of the habitat as substrates for microbial growth and mosquito feeding, particularly when nutrients (here, leachate) enter the system. Our results also illustrate the importance of soluble leaf material, which enhances mosquito production through effects on microbial community dynamics.