Carry-over effects of temperature on different life stages of Aedes albopictus: Linking larval environments to adult survival and fitness

Mosquitoes have evolved specific responses to variation in environmental conditions that could confer a fitness benefit or cost when carried-over across different life stages. Often, effects of temperature on mosquito population dynamics have focused on only part of their life cycle (e.g., aquatic phase). We investigated the response of intraspecific larval competition to temperature variation and examined “carry-over” effects of temperature from larval to adult stages in the Asian tiger mosquito, Aedes albopictus. For larval competition, 3 larval densities (10, 20, 40 individuals) were reared across 3 temperatures (21, 27, 34⁰C) with constant food and photoperiod. For the carry-over effects, adult survival was measured for males and females maintained within adult temperatures of 21, 27 and 34⁰C from the larval density with 20 individuals, at each larval rearing temperature (21, 27 and 34⁰C). Fecundity data also was obtained from mated females. There was a significant interaction between larval density and temperature, with increasing temperatures leading to decreases in both larval development times and adult mass, whereas increasing densities led to increasing development times but decreasing adult mass. In the carry-over effects experiment, a significant interaction was observed between larval rearing and adult temperatures, with the higher adult temperatures leading to greater differences in fecundity and adult survival of mosquitoes from larval rearing temperatures. Thus, it can be concluded that for Aedes albopictus, temperature affects the outcome of larval competition. Moreover, adult fitness is influenced by interactions of larval and adult temperatures, suggesting that investigations of effects of temperature based on a single life-history stage may be misleading. Future studies aim to address questions on life stage response of other mosquitoes to temperature variation and to other environmental factors.

Keywords: environmental factors, complex life cycles, fitness, mosquitoes