Résumé
Exposure to stress during an insect’s larval development can have
carry-over effects on many adult life history traits and affect host
susceptibility to pathogens. Studies on mosquitoes have shown that the
larval environment impacts on components of vectorial capacity such as
vector competence and adult survival. We investigated the carry-over
effects of larval nutritional stress for the first time on a natural
mosquito vector-malaria parasite association: Anopheles coluzzii exposed
to field isolates of Plasmodium falciparum. In contrast to previous
studies, we show that larval nutritional stress may affect human to
mosquito transmission antagonistically: nutritionally deprived larvae
showed lower parasite prevalence only on a subset of gametocyte carriers;
they also had lower fecundity. However, they had greater survival rates
that were even higher when infected. We combined these opposing effects
into epidemiological models to show that they depend on mosquito
densities. Larval nutritional stress induced a decrease in malaria
transmission at low mosquito density and an increase in transmission at
high mosquito densities, whereas transmission by mosquitoes from well-fed
larvae was stable. Our work underscores the importance of including larval
ecological factors towards understanding host – parasite dynamics, and the
need to confirm findings from artificial models on natural systems to
improve disease transmission models and control.