Aedes aegypti and Aedes albopticus

Vectors for:

Life cycle
and behavior

Aedes aegypti and Ae. albopticus are respectively the primary and secondary vectors for dengue fever. Ae. aegypti is the most important vector in the tropics and subtropical regions such as the southern United States. Ae. albopictus, noted by its striped legs and white eyes, is a major vector in Asia, especially in Japan, but it is being spread world wide as eggs are being carried in the ballast water of merchant ships. Species of Aedes spread far into temperate climatic areas and even into the Arctic.

Eggs of these mosquitoes, typically for culicines, are laid singly or in rafts and although they may stick to the surface, they may sink if the water is disturbed. Aedes prefers clean water for the development of the larvae and in tropical areas they will develop in water pots and tanks on roofs and in rain butts. Treatment of these habitats, even with safe insecticides, is often opposed as they are the only source of potable water. They also propagate in places such as unnoticed pools in discarded tires.

Disease is spread by females. Males do not bite. The females take blood meals that are used to support the development of eggs. Aedes is described as anthropophagic because it prefers to take its meals from humans. Dengue fever is primarily a disease of man for this reason, but yellow fever in its native environment is spread between humans and monkeys because mosquitoes that feed on carrier monkeys that live in jungle canopies can transmit the virus to humans through intermediate hosts. Aedes aegypti feeds throughout the day with peaks of activity at mid-morning and late afternoon.

Feeding is described as endophagic because the mosquito prefers to feed in and around structures and the mosquito then rests in cool damp spots within structures while the meal is digested (endophilic behavior). A blood meal takes 2-7 days to digest and 1-3 meals are needed to complete development of clutch of eggs. Transmission between humans comes from repeated biting when the mosquito injects saliva that acts as an anticoagulant.