2002 Volume 53 Issue 3 Pages 177-182
Gametocytes of malaria parasite undergo gamete formation in the mosquito midgut within minutes after ingestion of an infected blood meal. Male gametogenesis (exflagellation) of Plasmodium berghei, a rodent malaria parasite, can be induced in vitro by the combination of a reduction in temperature (from 37-39℃ in the rodent host to 21℃) and a simultaneous pH rise (from 7.3 in mouse blood to 8.0). We reported previously that the salivary gland (SG) of Anopheles stephensi (Liston) highly contained a gametocyte activating factor (GAF), which induced exfiagellation in P. berghei at the non-permissive pH. In the present study we compared exflagellation inducing activity (EIA) in the SGs of five mosquito species, Aedes aegypti (Linnaeus), Ae. albopictus (Skuse), An. omorii (Sakakibara), An. stephensi and Culex pipiens pallens (Coquillett). As a result, all the mosquito species examined contained GAF in the SGs. An. omorii and An. stephensi consumed more GAF than Ae. aegypti, Ae. albopictus and Cx. p. pallens during blood feeding, suggesting that more GAF might be introduced into the midgut of Anopheles mosquitoes. This would be one reason why only Anopheles mosquitoes can transmit mammalian malaria.
