Mortality of larval Aedes triseriatus and Aedes japonicus associated with fungal strains in laboratory and natural environments

It was recently observed that larvae of the mosquito Aedes triseriatus (Diptera: Culicidae) grown in the presence of dried leaves from certain populations of the sugar maple Acer saccharum developed slowly and had high mortality rates.  These effects were associated with the presence of fungal and/or oomycete populations on the leaf surface and in the water column. Challenging Ae. triseriatus larvae with spores from Aspergillus and Fusarium strains isolated from maple leaves resulted in more than 90% larval mortality. To further evaluate this phenomenon, larvae of additional laboratory strains of Ae. triseriatus, as well as larvae of the invasive species Ae. japonicus were exposed to isolates of Aspergillus and Fusarium spp. in both laboratory microcosms and manipulated natural field habitats. Preliminary results indicate that tested fungal strains cause significant larval mortality for both mosquito species in tree holes and similar habitats. These results underscore the complexity of interactions between naturally occurring microorganisms and larval mosquitoes that utilize these mixed microbial assemblages as food resources.