Ecological Factors Influencing <I>Aedes aegypti</I> (Diptera: Culicidae) Productivity in Artificial Containers in Salinas, Puerto Rico

Abstract

We investigated the effects of environmental factors and immature density on the productivity of Aedes aegypti (L.) and explored the hypothesis that immature populations were under nutritional stress. In total, 1,367 containers with water in 624 premises were studied in Salinas, southern Puerto Rico (May-July 2004). We counted 3,632 pupae, and most female pupae (70%) were in five of 18 types of containers. These containers were unattended and influenced by local yards' environmental conditions. Pupal productivity was significantly associated with the number of trees per premise, water volume, and lower water temperatures. Larval and pupal abundance were larger in containers with leaf litter or algae. Pupal productivity and biomass of emerging females varied in containers with litter of different tree species. We found a significant and positive association between numbers of larvae and pupae of Ae. aegypti and a negative relationship between larval density and mass of emerging females. From multivariate analyses, we interpreted that 1) food limitation or competition existed in a number of containers; and 2) to a lesser extent, there was lack of negative larval density effects in containers with a larger water volume and lower temperature, where emerging females were not under nutritional stress. Corroborating evidence for food limitation or intraspecific competition effects came from our observations that females emerging in the field had an average body mass comparable with those females produced in the laboratory with the lowest feeding regime. Ae. aegypti larvae in Salinas are most likely influenced by resource limitation or competition and by rainfall in unmanaged containers in the absence of aquatic predators. Source reduction and improved yard management targeting unattended containers would eliminate most Ae. aegypti productivity and removal or control of shaded, larger containers would eliminate the production of the largest emerging mosquito females in the study area.