Effect of leaf type and pesticide exposure on abundance of bacterial taxa in mosquito larval habitats

Sunday, November 10, 2013: 9:24 AM
Meeting Room 18 C (Austin Convention Center)
Ephantus J. Muturi , University of Illinois, Champaign, IL
Chang-Hyun Kim , University of Illinois, Champaign, IL
Lentic freshwater systems including those inhabited by aquatic stages of mosquitoes derive most of their carbon inputs from terrestrial organic matter mainly leaf litter. The leaf litter is colonized by microbial communities that in turn provide the resource base for mosquito larvae. While the microbial biomass associated with different leaf species in container aquatic habitats is well documented, the taxonomic composition of these microbes and their response to common environmental stressors is poorly understood. We used indoor aquatic microcosms to determine the abundances of major taxonomic groups of bacteria in leaf litters from seven plant species and their responses to low concentrations of four pesticides with different modes of action on the target organisms; permethrin, malathion, atrazine and gylyphosate. We tested the hypotheses that leaf species support different quantities of major taxonomic groups of bacteria and that exposure to pesticides at environmentally-relevant concentrations alters bacterial abundance and community structure in mosquito larval habitats. We found support for both hypotheses suggesting that leaf litter identity and chemical contamination can alter the quality and quantity of the mosquito food base (microbial communities) in larval habitats. The effect of pesticides on microbial communities varied significantly among leaf types suggesting that the impact of pesticides on natural microbial communities may be highly complex and difficult to predict. Collectively, these findings demonstrate the potential for detritus composition within mosquito larval habitats and exposure to pesticides to influence mosquito production and the risk of mosquito-borne diseases.