Laboratory Study of Competition Between United States Strains of Aedes albopictus and Aedes aegypti (Diptera: Culicidae)

Abstract

Mosquito abatement workers in Houston, Tex., and New Orleans, La., have observed that the recent introduction of Aedes albopictus (Skuse) has been accompanied by a decline and virtual disappearance of Ae. aegypti (L.). This suggests competitive displacement but contradicts the direction of displacement observed in native habitats of Ae. albopictus. The paper reports a series of laboratory studies on competition between U.S. strains of the two species. Larval survivorship, size, and development time were monitored in increasing densities of pure and mixed cultures of the two species under limited and optimal diets. Oviposition preferences were examined by offering gravid females cups containing first or fourth instars of either species. Ethological isolation was studied by simultaneously offering virgin females of one species to males of both species and monitoring courtship behavior as well as rates of oviposition, percentage of hatch, and embryonation. The results of the larval competition studies suggest that interspecific competition increased development time only slightly and had no effect on survival of Ae. albopictus. Competition increased survival in Ae. aegypti. Size of both species was influenced by interspecific competition, but the magnitude and direction of the effect was inconsistent between strains and diets such that neither species emerged consistently larger. The results of the oviposition study indicated a higher fecundity in Ae. aegypti but otherwise demonstrated that both species oviposit without regard to the presence, age, or species of larvae in the oviposition container. The ethological isolation tests demonstrated that Ae. aegypti males were more sexually aggressive than males or Ae. albopictus. However, Ae. albopitus females placed with increasing densities of Ae. aegypti males demonstrated no decrease in rates of oviposition, and eggs laid showed equal rates of hatch and embryonation. In general, the results do not suggest that the U.S Ae. albopictus population is inherently more competitive in the laboratory than Ae. aegypti. Other reasons for the observed decline in Ae. aegypti in the United States are discussed.

Geographic Variation in Adult Survival and Reproductive Tactics of the Mosquito Aedes albopictus

“…albopictus in the United States were interpreted as indicating rapid local differentiation (Black et al 1988). Similar patterns of isozyme variation were detected at the heart of its native range in the tropics, suggesting that local genetic differentiation is characteristic of this species (Black et al 1989). Hence, many North American populations seem sufficiently isolated in climatically different habitats to allow for local adaptation if appropriate selection exists.…”

Clima e sobreposição da distribuição de Aedes aegypti e Aedes albopictus na infestação do Estado de São Paulo

“…albopictus, pois oscilações na abundância daquela espécie já ocorreram nesse país, principalmente nas décadas de 50 e 60. 1,10,15 Em 1986, um ano depois da detecção de municípi-os infestados por Ae. aegypti a Oeste do Estado de São Paulo, 6 foi registrada a introdução de Ae.…”

The spatial distribution of Aedes aegypti and Aedes albopictus in a transition zone, Rio de Janeiro, Brazil

“…Early work suggested Ae. aegypti to be the superior competitor 7 . More recent works, however, have shown that Ae.…”