The invasive mosquito Aedes albopictus illustrates the importance of behavioral tradeoffs for determining invasion outcomes. Invasion by A. albopictus results in declines of Aedes aegypti, but no declines of Ochlerotatus triseriatus. This difference in outcome is affected by behavioral tradeoffs of competitive ability and predator avoidance. Aedes albopictus encounters O. triseriatus in water-filled treeholes in forests, along with predatory Toxorhynchites rutilus and Corethrella appendiculata. Aedes albopictus is more vulnerable to these predators, and also is more active, forages more, and is a better competitor than O. triseriatus. Ochlerotatus triseriatus shows strong, threat-sensitive reductions in foraging, movement, and subsurface time in response to water-borne cues from predators, responses that are absent (T. rutilus) or reduced (C. appendiculata) in A. albopictus. In treeholes, A. albopictus and O. triseriatus are equally abundant, suggesting predator-mediated coexistence. Manipulations show that C. appendiculata impedes invasion by A. albopictus, but that O. triseriatus does not. Outside of treeholes, A. albopictus primarily encounters A. aegypti, predators are rare, A. albopictus is abundant, and A. aegypti has declined or been eliminated. In experiments, A. albopictus is superior in competition to A. aegypti. Behavioral responses to resources may contribute to the competitive advantage of A. albopictus. Compared to A. aegypti, A. albopictus forages more, particularly at surfaces of detritus, suggesting greater resource harvesting. Thus, competitive success of A. albopictus appears to depend on foraging, with associated cost of greater predation risk. This tradeoff influences exclusion of poorer competitors without predators, or predator-mediated coexistence with less vulnerable, less competitive species.
