Understanding the biology and behavior of Anopheles mosquitoes can help us understand how malaria spread occurs and can aid in designing appropriate malaria-control strategies. Factors to consider include the mosquito's:
- Susceptibility to Plasmodium (the parasites that cause malaria)
- Host choice for meals (humans versus animals)
- Life span
- Susceptibility to insecticides
- Preferred feeding and resting location.
Susceptibility to Plasmodium
Some Anopheles 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 strains of Anopheles gambiae that cannot become infected by malaria parasites. Scientists are studying the genetic mechanism for this ability. It is hoped that some day, genetically modified Anopheles mosquitoes that cannot transmit the malaria parasite can replace wild mosquitoes, thereby limiting or eliminating malaria spread.
Choice for Meals
One important factor in understanding Anopheles and malaria transmission is the degree to which a species prefers to feed on humans or animals, such as cattle. Most Anopheles mosquitoes do not exclusively prefer humans or animals; however, the primary species in Africa, Anopheles gambiae and Anopheles funestus, strongly favor humans and, consequently, are two of the most efficient malaria vectors in the world.
Once ingested by a mosquito, malaria parasites must undergo development before they are infectious to humans. The time required for development of Plasmodium in the Anopheles mosquito ranges from 10 to 21 days, depending on the parasite species and the temperature. If a female mosquito does not survive long enough, she will not be able to transmit any malaria parasites.
It is estimated that about 20 percent of Anopheles mosquitoes survive longer than 14 days.