The Anopheles Mosquito:
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There are approximately 400 species of Anopheles mosquito, of which 30-40 transmit four different species of parasites of the genus Plasmodium that cause malaria which affects humans in endemic areas. Anopheles gambiae is one of the best known, because of its predominant role in the transmission of the most dangerous Plasmodium falciparum.
Like all mosquitoes, anopheles go through four stages in their life cycle: egg, larva, pupa, and imago. The first three stages are aquatic and last 5-14 days, depending on the species and the ambient temperature. The adult stage is when the female Anopheles mosquito acts as a malaria vector. The adult females can live up to one month but probably no more than 1-2 weeks in nature.
Anopheles mosquitoes can be distinguished from other mosquitoes by the palps, which are as long as the proboscis, and by the presence of discrete blocks of black and white scales on the wings.
Some species are poor vectors of malaria, as the parasites do not develop well (or at all) within them. There is also variation within species. In the laboratory, it has been possible to select for strains of A. gambiae that are refractory to infection by malaria parasites. These refractory strains have an immune response that encapsulates and kills the parasites after they have invaded the mosquito's stomach wall. Scientists are studying the genetic mechanism for this response. It is hoped that some day, genetically modified mosquitoes that are refractory to malaria can replace wild mosquitoes, thereby limiting or eliminating malaria transmission.
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