Effect of rearing temperature and larval density on larval survival, age at pupation and adult size of Anopheles gambiae


Swiss Tropical Institute, Socinstr. 57, CH-4002 Basel, Switzerland; current address: Department of Biology, Imperial College, Prince Consort Road, London SW7 2BB, England


The effects of temperature and larval density on survival of larvae, growth rate, age at pupation, and adult size (measured as wing length and dry weight) of laboratory-reared Anopheles gambiae (Diptera: Culicidae) were studied. Larvae were reared at three temperatures (24, 27 and 30 °C) and three densities (0.5, 1 and 2 larvae/cm2). The effects of density and temperature strongly interacted to determine the mosquitoes' life-history parameters. Survival was highest at the intermediate temperature of 27 °C. The differences between the temperatures increased with increasing density. At 30 °C survival decreased as density increased, but at 27 °C increasing density led to higher survival. Age at pupation increased as temperature decreased from 30 °C to 24 °C and as density decreased from 2 to 0.5 larvae/cm2. Adult size also increased as temperature decreased, but showed a negative correlation with density only at 27 °C. In contrast, at 24 °C and 30 °C a decrease in density led to a decrease in adult size. Growth rate showed a similar pattern. At 27 °C growth rate decreased as density increased, but at other temperatures the opposite trend was observed.