The effect of biotic and abiotic stress on mosquito fitness and behaviour: a tale of four species

The effect of temperature on fitness and behaviour of medically important mosquitoes has predominantly been evaluated under constant temperatures, yet in their natural habitats, mosquitoes experience fluctuating temperatures, and this may be more extreme under future changing climates. Food resource abundance in aquatic habitats fluctuates with temperature. How these two environmental factors interact to affect the life history of con-specific and hetero-specific mosquitoes during aquatic development, and fitness benefits carried over to adults is underexplored. Therefore, larvae of Aedes aegypti, Anopheles stephensi, Anopheles coluzzii and Anopheles arabiensis were reared under varying diurnal fluctuating temperatures and maintained on different larval resource levels (paper I and II). In addition, the effects of temperature on dynamic feeding of female An. coluzzii was evaluated (paper III). Shortened time to adult emergence, diminished adult size and longevity were observed at high temperature, in a resource- and genera-dependent manner (paper I and II). Moreover, teneral metabolic reserves carried-over to adults, as well as feeding propensity of teneral females, varied across temperature and resource regimes, in a genera-dependent manner (paper I). Aedes aegypti was a dominant competitor due to accelerated adult emergence, bigger sized females and longer adult survival compared to An. stephensi (paper II). Moreover, at low temperature, An. coluzzii was a dominant competitor with longer survival compared to An. arabiensis (paper II). Dynamic feeding of An. coluzzii on carbohydrate-, nitrogen- or proteinaceous-rich meal varied with female maturation, in a temperature-dependent manner (paper III). Findings from this study underscore the effects of biotic and abiotic stress on mosquito fitness traits and behaviour that are key to population growth rate, community structure and vectorial capacity.