Mosquito-Borne Diseases

Abstract

Mosquitoes are flies, and thus, undergo complete metamorphosis, having egg, larval, pupal, and adult stages. Larvae are commonly referred to as wigglers and pupae as tumblers. Larvae and pupae of mosquitoes are always found in water. Breeding sites maybe anything from water in discarded automobile tires to water in the axils of plants, to pools, puddles, swamps, and lakes. Mosquito species differ in their breeding habits, biting behavior, flight range, and so forth (Fig. 1). However, a generalized description of their life cycle is presented here as a basis for understanding mosquito biology and ecology. There are three subfamilies in the mosquito family (Culicidae)—Anophelinae, Culicinae, and Toxorhynchitinae. Members of the Toxorhynchitinae are huge, non-bloodsucking mosquitoes whose larvae eat mosquito larvae of other species. The larvae have a breathing tube (siphon), but it is short and conical. Most larvae in the subfamily Culicinae hang down just under the water surface by the siphon, whereas anopheline larvae lie horizontally just beneath the water surface supported by small notched organs of the thorax and clusters of float hairs along the abdomen (Fig. 2). They have no prominent siphon. Mosquito larvae feed on suspended particles in the water as well as microorganisms. They undergo four molts (each successively larger), the last of which results in the pupal stage. With optimal food and temperature, the time required for larval development can be as short as 7 d.