Analysis of the ecological and genetic bases of mosquito fitness in two major malaria vectors
Malaria is an infectious disease caused by Plasmodium parasites that are transmitted by mosquito vectors (Anopheles species), responsible for thousands of deaths annually. Mosquito longevity is the most important factor in malaria transmission, as the parasite requires ~2 weeks to develop inside the vector before the mosquito can infect a new host.
Mosquito longevity is influenced by several factors including:
i) the species, remarkably two of the major vectors in Africa - Anopheles gambiae and An. arabiensis - show different lifespans;
ii) adult body size, which is strongly dependent on larval environment and development;
iii) the host-species mosquitoes feed on, which influences their fecundity and survival.
An. gambiae and An. arabiensis differ in their feeding preference - preferentially biting humans or cows respectively – and in their host-species dependent fitness. In addition to these ecological determinants, longevity can be shaped by natural selection, and it has been predicted that the current widespread use of vector control interventions could select populations with reduced lifespan in favour of enhanced short-term reproduction.
Despite the importance to malaria transmission, almost nothing is known about the mechanistic basis of mosquito variation in survival and its associated impacts on reproduction, which is crucial to understand how some ecological factors and selection pressures may influence mosquito survival and disease transmission potential. Studies of a wide range of organisms from Drosophila to humans have shown that variation in survival and reproduction is often linked to the insulin/insulin growth factor I signalling (IIS) and TOR pathways.
This project will investigate how extrinsic and intrinsic factors that influence survival and reproductive success modulate IIS/TOR pathway response in malaria mosquitoes in order to elucidate the molecular architecture behind vector longevity as a potential new target for insecticide formulations and genetic modifications.
First published: 10 August 2014