Temperature-related duration of aquatic stages of the Afrotropical malaria vector mosquito Anopheles gambiae in the laboratory

Vector abundance is an important factor governing disease risk and is often employed when modelling disease transmission. The longevity of the aquatic stages of mosquitoes (Diptera: Culicidae) dictates the rate of production of adults and hence the intensity of disease transmission. We examined how temperature influences the survival of larval stages (larvae and pupae) of Anopheles gambiae Giles sensu stricto and subsequent adult production of this most efficient malaria vector. Groups of 30 mosquitoes were reared at constant temperatures (from 10 to 40 degreesC) from the first instar and observed until death or metamorphosis of the last individual. Larvae developed into adults at temperatures ranging from 16 to 34 degreesC. Larval survival was shortest (< 7 days) at 10-12 degreesC and 38-40 degreesC, and longest (> 30 days) at 14-20 degreesC. Within the temperature range at which adults were produced, larval mortality was highest at the upper range 30-32 degreesC, with death (rather than adult emergence) representing over 70% of the terminal events. The optimal survival temperatures were lower than the temperatures at which development was quickest, suggesting a critical relationship between temperature and the life cycle of the insect. These data provide fundamental information about An. gambiae s.s. adult productivity at different temperatures, which may facilitate the construction of process-based models of malaria risk in Africa and the development of early warning systems for epidemics.