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
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.