Culex: A genus of mosquitoes (CULICIDAE) commonly found in tropical regions. Species of this genus are vectors for ST. LOUIS ENCEPHALITIS as well as many other diseases of man and domestic and wild animals.Insect Vectors: Insects that transmit infective organisms from one host to another or from an inanimate reservoir to an animate host.Culicidae: A family of the order DIPTERA that comprises the mosquitoes. The larval stages are aquatic, and the adults can be recognized by the characteristic WINGS, ANIMAL venation, the scales along the wing veins, and the long proboscis. Many species are of particular medical importance.Insecticide Resistance: The development by insects of resistance to insecticides.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.Aedes: A genus of mosquitoes (CULICIDAE) frequently found in tropical and subtropical regions. YELLOW FEVER and DENGUE are two of the diseases that can be transmitted by species of this genus.West Nile virus: A species of FLAVIVIRUS, one of the Japanese encephalitis virus group (ENCEPHALITIS VIRUSES, JAPANESE). It can infect birds and mammals. In humans, it is seen most frequently in Africa, Asia, and Europe presenting as a silent infection or undifferentiated fever (WEST NILE FEVER). The virus appeared in North America for the first time in 1999. It is transmitted mainly by CULEX spp mosquitoes which feed primarily on birds, but it can also be carried by the Asian Tiger mosquito, AEDES albopictus, which feeds mainly on mammals.Insecticides: Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.Mosquito Control: The reduction or regulation of the population of mosquitoes through chemical, biological, or other means.West Nile Fever: A mosquito-borne viral illness caused by the WEST NILE VIRUS, a FLAVIVIRUS and endemic to regions of Africa, Asia, and Europe. Common clinical features include HEADACHE; FEVER; maculopapular rash; gastrointestinal symptoms; and lymphadenopathy. MENINGITIS; ENCEPHALITIS; and MYELITIS may also occur. The disease may occasionally be fatal or leave survivors with residual neurologic deficits. (From Joynt, Clinical Neurology, 1996, Ch26, p13; Lancet 1998 Sep 5;352(9130):767-71)Chemosterilants: Compounds that cause reproductive sterility in organisms. They are sometimes used to control pest populations by sterilizing males within the population.Flavivirus: A genus of FLAVIVIRIDAE containing several subgroups and many species. Most are arboviruses transmitted by mosquitoes or ticks. The type species is YELLOW FEVER VIRUS.Pest Control, Biological: Use of naturally-occuring or genetically-engineered organisms to reduce or eliminate populations of pests.Disease Vectors: Invertebrates or non-human vertebrates which transmit infective organisms from one host to another.Filariasis: Infections with nematodes of the superfamily FILARIOIDEA. The presence of living worms in the body is mainly asymptomatic but the death of adult worms leads to granulomatous inflammation and permanent fibrosis. Organisms of the genus Elaeophora infect wild elk and domestic sheep causing ischemic necrosis of the brain, blindness, and dermatosis of the face.Oviposition: The process of laying or shedding fully developed eggs (OVA) from the female body. The term is usually used for certain INSECTS or FISHES with an organ called ovipositor where eggs are stored or deposited before expulsion from the body.Anopheles: A genus of mosquitoes (CULICIDAE) that are known vectors of MALARIA.Wolbachia: A genus of bacteria comprised of a heterogenous group of gram-negative small rods and coccoid forms associated with arthropods. (From Bergey's Manual of Systematic Bacteriology, vol 1, 1984)Insect Repellents: Substances causing insects to turn away from them or reject them as food.Wuchereria: A genus of filarial nematodes.Population Density: Number of individuals in a population relative to space.Oviparity: The capability of producing eggs (OVA) from which young are hatched outside the body. While mostly referring to nonmammalian species, this does include MAMMALS of the order MONOTREMATA.