Aedes (Finlaya) japonicus japonicus (Theobald) is invasive in the U.S., Canada, and western and central Europe. This species breeds in water-filled container habitats where it overlaps with local species including Aedes triseriatus and Culex pipiens. Because larvae of A. j. japonicus often occur in sunlit containers with visible algal growth, we hypothesized that gravid A. j. japonicus females would be more likely to deposit eggs in containers with algae, and that larval production and competitive ability would be enhanced in these containers. Results of our studies indicate that algae in larval habitats are not a major factor in oviposition choices of adult A. j. japonicus females except when algal production is high enough to substantially alter overall organic matter content cues. Additionally, our results indicate that algae do provide an overall benefit to mosquito larvae by enhancing development and emergence rates, but do not alter outcomes of resource competition. We observed substantial competitive asymmetry between A. j. japonicus and C. pipiens, as no C. pipiens individuals survived the experiment when in competition with A. j. japonicus, but not between A. j. japonicus and A. triseriatus. Aedes j. japonicus survival rates were not affected by algae, and A. j. japonicus females emerged faster than the other species regardless of algal density. Evidence from these studies suggests that this species may be better able to tolerate low-resource conditions than its competitors, and that habitat generalism may contribute to the success of A. j. japonicus as an invader.
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