Malaria: Anopheles mosquitoes

Malaria is transmitted by Anopheles mosquitoes. This applies to the malaria of all mammals. Avian malaria on the other hand is chiefly transmitted by Culicinae. There are some 400 Anopheles species, 40 of which are good vectors while 28 are poor vectors. Anopheles mosquitoes are relatively small (8 mm), two-winged insects (Diptera; Gr. di = two and pteryx = wing) sometimes with a typical posture while feeding: head down and the lower body upwards. [There are exceptions to this such as Anopheles culicifacies, which, as its name suggests, is similar in posture to Culex.] As with many mosquitoes there are countless scales on the body and wings. In Anopheles there are darker and lighter coloured scales arranged in groups, which produces a distinctive marking on the wing (a speckled pattern). Culex mosquitoes on the other hand are of an even colour. Anopheles mosquitoes undergo induced color change based on perception of the background against which they are cultured. When larvae are reared on either a black or white background, they become pigmented dark or pale. The degree of darkening depends in part on the length of time the larvae have been cultured on a black background and the degree of fat body development. This color change phenomenon is called homochromy. Anopheles mosquitoes are active at night. They do not buzz much and are not easily noticed. Every species of mosquito has its own characteristics as to behaviour, reproduction, biting habits, etc. This is of course important for mosquito control.

Category: Medicine Notes