Relative roles of aggregation, competition, and predation in the North American invasion of the Asian Bush mosquito, Aedes japonicus

Abstract

The success of an invasion can be mediated by biological interactions (e.g. competition and predation). The newly invasive mosquito <italic>Aedes japonicus</italic> has established in the range of the competitively superior resident mosquito <italic> Aedes albopictus </italic> and the predatory indigenous mosquito <italic>Toxorhynchites rutilus</italic>. I tested the hypotheses that intraspecific aggregation, fluctuating resources, or keystone predation are facilitating the invasion of <italic>A. japonicus</italic> into the range of <italic>A. albopictus</italic>. Populations of <italic>A. japonicus</italic> and <italic>A. albopictus</italic> were negatively correlated with each other and intraspecifically aggregated in field studies, suggesting that aggregation is facilitating coexistence. Resources showed a high amount of spatial variability, and <italic>A. japonicus</italic> populations were strongly associated with resource-rich containers, providing evidence for the fluctuating resource hypothesis. A laboratory experiment showed that predation suppresses <italic>A. japonicus</italic> populations to a greater extent than interspecific competition when all three species co-occur, and provided no evidence for keystone predation.