The geographical distribution and abundance of competent vectors underpins disease transmission patterns. Ecological metabolic theory (EMT) and the size-temperature rule (TSR) provide a mechanistic basis for predicting how mosquito populations will respond to climate warming. EMT predicts that population-level fitness, like its component traits, increases approximately with temperature up to an optimum. TSR predicts that ectotherm body size generally follows an inverse relationship with temperature. However, these prominent expectations are largely untested across varying levels of temperature and resource supply. Here, we ask whether and how variations in resource supply mediate fundamental size and the temperature-dependencies of life history traits and emergent fitness of a principle vector of arbovirus pathogens, Aedes aegypti.
We exposed juvenile mosquitoes to levels of temperature and resource supply and measured their independent and their interactive effects on body size and trait performance. We estimated fitness by using these data to parameterise Age-structured Population Projection Matrices.
Results/Conclusions
With high-resource supply, population-level fitness was predicted to be positive and to increase approximately exponentially with temperature. With resource limitation, fitness was negative and concavely shaped. Resource limitation compounded fitness by lengthening juvenile development, decreasing body size and adult lifespan, and diminishing fecundity due to size-scaling effects. However, the most important effect of resource limitation on fitness derived from how it significantly increased juvenile mortality. We show how resource supply can modulate the temperature dependence of fitness in an important disease vector. The accuracy of projections of how vectors will respond to environmental change may be improved if both temperature and resource supply are considered. Our findings also suggest that vector interventions may be enhanced by knowledge of how both temperature and resource supply vary in natural settings to drive vector demographics and disease transmission patterns.