Nutritional availability and larval density dependence in Aedes aegypti

Abstract

1. Density dependence is the effect of density on population growth. Density dependence is an aggregate term for a suite of complex interactions between animals and their environment.2. Mechanistic studies of density dependence in mosquito ecology are sparse, and the role of environmental factors is poorly understood.3. Two empirical study designs were compared to consider the interaction between nutritional availability and density in Aedes aegypti. First, larvae were fed per capita. Second, larvae were fed a fixed amount of food unadjusted for the number of individuals; therefore, at higher densities, individuals received less per capita.4. Survivorship, wing length, and development rate were lower at high densities when larvae were fed a fixed, unadjusted amount of food. The opposite was observed when food was adjusted per capita, suggesting that high densities may be beneficial for larval development when per capita nutrition is held constant5. These results demonstrate that negative associations between Ae. aegypti larval density and larval development are a manifestation of decreased per capita nutrient uptake at high densities.6. Population regulation is a proportional response to environmental variability in Ae. aegypti. Increased survivorship at high densities when larvae were fed per capita demonstrates that nutritional availability is not the only mechanism of density dependence in mosquitoes. Further studies should characterise density dependence in mosquitoes by using mechanistic study designs across diverse environmental conditions.