Life Cycle of Aedes Aegypti
As its name implies, Aedes aegypti is originally from Africa. Today, it is seen worldwide and is most prevalent in tropical and subtropical climates. The species has been observed in cooler, more temperate climates. Ae. aegypti is known as the yellow fever mosquito because of its role in spreading that disease. It is a primary vector in spreading dengue fever as well. This species also is implicated in the spread of West Nile virus, chikungunya fever and heartworm in domestic animals. Aedes aegypti lives in habitats close to humans. It is important to understand the life cycle of this pest to better control it. As with other flies, Ae. aegypti goes through a complete metamorphosis with egg, larval, pupal and adult stages.
Mating
Males and females mate shortly after emerging from their pupal cases. Male mosquitoes live only a few days after mating, feeding on plant nectar until they die. The fertilized female must have one to three blood meals to allow her eggs to mature for laying. Each blood meal takes two to seven days to digest. The female can produce up to 200 eggs per clutch after three blood meals. The number of eggs produced depends on the amount of blood consumed. Each female is capable of producing up to five clutches in her lifetime.
Eggs, Embryos and Hatching
Aedes aegypti females usually lay their eggs singly, though they can be laid in a raft. Eggs are laid near water where flooding and raised water levels generally occur. Initially white eggs turn a shiny black color a few minutes after being laid. Eggs can survive several months if desiccated. When wet, the eggs hatch into larvae in two to seven days based upon the climate and temperature.
Larval Growth
Mosquito larvae are commonly called "wrigglers" because of their behavior of wiggling when disturbed. Larvae hang head down from the surface of the water with their posterior breathing tube (siphon) extended above the surface for air. The larvae feed on algae and microorganisms filtered from the water by their mouthparts. The larva quickly moves through the first three stages (instars) as they grow rapidly and require molting. The larva stays in the fourth instar stage longer than the previous stages, usually three days under ideal conditions. Ae. aegypti larva can survive up to a month under cold conditions.
Pupation and Metamorphosis
After reaching maturity, the fourth instar enters the pupal stage. The pupa is located on the surface of the water where it breathes through a pair of air tubes or trumpets. This stage of the mosquito is commonly referred to as a "tumbler." The pupae of mosquitoes are mobile and respond to stimuli. The pupae do not feed. They take about two days to mature. Inside the pupal case metamorphosis occurs changing the larval form into an adult with legs, wings, compound eyes, and sucking mouthparts.
Adult Emergence and Renewal of the Cycle
The adult emerges from the pupal case after about two days. The adult ingest air to expand their abdomen. This splits the pupal case allowing the adult to emerge head first. The adults move from the surface of the water to cool, moist areas where they mate and begin the life cycle again.
Tags: pupal case, surface water, about days, Aedes aegypti, blood meals