Susceptibility of Anopheles gambiae and Anopheles stephensi to tropical isolates of Plasmodium falciparum

Jennifer CC Hume, Mark Tunnicliff, Lisa C Ranford-Cartwright, Karen P Day

The susceptibility of anopheline mosquito species to Plasmodium infection is known to be variable with some mosquitoes more permissive to infection than others. Little work, however, has been carried out investigating the susceptibility of major malaria vectors to geographically diverse tropical isolates of Plasmodium falciparum aside from examining the possibility of infection extending its range from tropical regions into more temperate zones. This study investigates the susceptibility of two major tropical mosquito hosts (Anopheles gambiae and Anopheles stephensi) to P. falciparum isolates of different tropical geographical origins. Cultured parasite isolates were fed via membrane feeders simultaneously to both mosquito species and the resulting mosquito infections were compared. Infection prevalence was variable with African parasites equally successful in both mosquito species, Thai parasites significantly more successful in An. stephensi, and PNG parasites largely unsuccessful in both species. Infection success of P. falciparum was variable according to geographical origin of both the parasite and the mosquito. Data presented raise the possibility that local adaptation of tropical parasites and mosquitoes has a role to play in limiting gene flow between allopatric parasite populations.