Microscopic Detail of Mosquito's Exoskeletal Surface
At a moderately high magnification of 801x, this scanning electron micrograph reveals some of the morphologic features displayed on the exoskeletal surface of an Anopheles gambiae mosquito. In the field of view is the left mesothoracic spiracle, which is a cavernous depression in the exterior thoracic surface through which the mosquito's breathing occurs. Note the multitude of sensorial hairs, know as setae, which cover the surface and the pit's interior. The globular material seeming to coat the setae represents particulate matter picked up by the mosquito from its environment. There are approximately 3,500 species of mosquitoes grouped into 41 genera. Human malaria is transmitted only by females of the genus Anopheles. Of the approximately 430 Anopheles species, only 30-40 transmit malaria in nature. An organism that transmits a disease to another organism is known as a vector. One important behavioral factor is the degree to which an Anopheles species prefers to feed on humans, referred to as anthropophily, or animals such as cattle referred to as zoophily. Anthropophilic Anopheles are more likely to transmit the malaria parasites from one person to another. Most Anopheles mosquitoes are not exclusively anthropophilic or zoophilic. However, the primary malaria vectors in Africa, Anopheles gambiae, and Anopheles funestus, are strongly anthropophilic and, consequently, are two of the most efficient malaria vectors in the world.