a1 Ifakara Centre, Box 53, Ifakara, Tanzania
a2 Swiss Tropical Institute, Socinstrasse 57, CH-4002 Basel, Switzerland
The influence of adult female body size of Anopheles gambiae s.l. on development of midgut and salivary gland infections by the parasite Plasmodium falciparum was investigated in a field study carried out in Tanzania. The proportion of mosquitoes infected during a blood meal was independent of size. However, the number of oocysts harboured by infected mosquitoes increased with size of the mosquito. The proportion of mosquitoes with sporozoites, and thus potentially infective to humans, was highest in intermediate-sized mosquitoes, whereas the largest and smallest mosquitoes were less likely to have sporozoites. This pattern is interpreted as a combination of high survival rate of large, uninfected mosquitoes and of low survival rate of mosquitoes infected with many oocysts.
(Received July 02 1991)
(Revised August 22 1991)
(Accepted August 23 1991)
p1 Present address and address for reprint requests: Department of Biology, Imperial College, Prince Consort Road, London SW7 2BB, UK.