Interspecific Competition Between Two Invasive Species of Container Mosquitoes, Aedes aegypti and Aedes albopictus (Diptera: Culicidae), in Brazil

As a result of numerous successful invasions by bothAedes albopictus (Skuse) andAdes aegypti (L.), the current worldwide distributions of these mosquito species overlap. Shared larval habitats and shifts in the distribution and abundance of resident A. albopictus or A. aegypti after the establishment of the other species suggest that competitive displacement occurs. Experiments on larval competition betweenNorth American populations of the two species showed thatA. albopictus has the competitive advantage under local Þeld conditions, which apparently accounts for displacement of A. aegypti from much of the United States after the invasion of A. albopictus. The role of competition, and potential shifts of competitive advantage in different parts of their worldwide ranges are unknown, but variationdue to intraspeciÞc or environmental differences is possible. In the current study, we measured the performance of larvae of Brazilian populations of A. albopictus and A. aegypti competing under Þeld conditions in Rio de Janeiro, Brazil. Finite rates of increase for each species were estimated and the effects of species composition, larval density, and leaf litter resource levels were determined. A. albopictus maintained positive population growth at higher combined densities and lower per capita resource availability than didA. aegypti. A. albopictus showedhigher survivorship thanA. aegypti under all treatments and leaf litter resource levels. These results indicate that in Brazil, just as in North America, A. albopictus is a superior larval competitor to A. aegypti when exploiting leaf litter resources. Our results further suggest that this competitive advantage for A. albopictus is likely to be independent of mosquito population origin, local environmental conditions, and local differences in the types of leaves that form the resource base of the aquatic habitats of larvae.