Survival and development of Aedes triseriatus, the mosquito vector of La Crosse Encephalitis, were found to be inhibited in the presence of dried leaves of certain populations of the sugar maple Acer saccharum. It is suspected that these effects are due to fungal contaminants carried on the leaf surface. Pure cultures of Aspergillus niger and Fusarium oxysporum were isolated from experimental containers in which these effects were observed. Pure cultures were used to challenge larvae of Ae. triseriatus and the invasive species Aedes japonicus japonicus. Results indicate that Aspergillus spores have a significant and repeatable lethal effect on larvae of the tested species, particularly those at the first and second instar. Results also indicate a significant inhibition of development in some experiments. Also implied is a possible competitive advantage of Ae. j. japonicus over Ae. triseriatus when exposed to spores of the fungus Aspergillus, as Ae. j. japonicus rates of survival were significantly higher than those of Ae. triseriatus when run concurrently.
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