|Male Culex sp.|
|Over 1000 species|
Culex is a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans and other animals. The diseases they vector include Arbovirus infections, West Nile virus, filariasis, Japanese encephalitis, St. Louis encephalitis, and avian malaria.
Depending on the species, the adult Culex mosquito may measure from 4–10 mm (0.2–0.4 in). The adult morphology is typical of flies in the suborder Nematocera with the head, thorax, and abdomen clearly defined and the two fore wings held horizontally over the abdomen when at rest. As in all Diptera capable of flight, the second pair of wings are reduced and modified into tiny, inconspicuous halteres.
Formal identification is important in mosquito control, but it is demanding and requires careful measurements of bodily proportions and noting the presence of absence of various bristles or other bodily features.
In the field informal identification is more often important, and the first question as a rule is whether the mosquito is anopheline or culicine. Given a specimen in good condition, one of the first things to notice is the length of the maxillary palps. Especially in the female, palps as long as the proboscis are characteristic of anopheline mosquitoes. Culicine females have short palps. Anopheline mosquitoes tend to sit with their heads low and their rear ends raised high, especially when feeding, while culicine females keep their bodies horizontal.
Anopheline larvae tend to float horizontal at the surface of the water when not in motion, whereas culicine larvae float with head low and only the siphon at the tail held at the surface.
The developmental cycle of most species takes about two weeks in warm weather. The metamorphosis is typical of holometabolism in an insect: The female lays eggs singly or in batches, depending on the species. Eggs hatch only in the presence of water and the larvae are obligately aquatic, linear in form, and maintain their position and attitude in water by movements of their bristly mouthparts. To swim more actively, they lash the body back and forth through the water.
During the larval stage, the mosquito lives in water and feeds on particles of organic matter, microscopic organisms or plant material; after several instars it then develops into a pupa. Unlike the straight-bodied larva, the pupa is comma-shaped and also lives in water. It does not feed and becomes an adult after one or two days.
Diseases borne by one or more species of Culex mosquitoes vary in their dependence on the species of vector. Some are rarely and only incidentally transmitted by Culex species, but Culex and closely related genera of culicine mosquitoes readily support perennial epidemics of certain major diseases if they become established in a particular region.
- Arbovirus infections transmitted by various species of Culex include West Nile virus, Japanese encephalitis, St. Louis encephalitis and Western and Eastern Equine Encephalitis.
- Nematode infections, mainly forms of filariasis may be borne by Culex species as well as by other mosquitoes and blood-sucking flies.
- Protist parasites in the Apicomplexa, such as various forms of avian malaria
Culex is a diverse genus. It comprises over twenty subgenera that include a total of well over a thousand species. Descriptions of additional species are frequent.
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- on the UF / IFAS Featured Creatures Web site
- Culex pipiens at MetaPathogen: facts, life cycle
- Mosquito Chapter in the National Public Health Pesticide Applicator Training Manual