Characterization and inhibitory effect of Pythium sp. in Aedes triseriatus larval rearing containers

Laboratory experiments in aquatic microcosms showed that growth of larvae of the eastern treehole mosquito, Aedes triseriatus, which is a known vector of La Crosse Encephalitis, was stalled in the presence of senescent sugar maple leaves and filamentous blooms on the leaves and in the water column. The phenomenon, by contrast, was not observed when red oak leaves were provided and larval growth was not inhibited. 18S rDNA sequence analysis indicated that fungi in the water column were predominantly Aspergillus spp. along with other fungi in a consortium. ITS1/5.8S PCR also indicates the presence of fungus-like oomycetes in the genus Pythium. The observed dampening of larval growth appears to be associated with maple leaves from specific collection dates and times and is not ubiquitous in maple leaves. The current study looks at characterizing the interaction between the Pythium organism believed to be responsible for the majority of the inhibitory effects and the larval treehole mosquitoes. The significance of these results to growth and production of mosquitoes from heterotrophic container habitats will be discussed.