Culex

 

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IMPORTANCE:

    Members of the Culex pipiens complex are the principal vectors of St. Louis encephalitis (SLE) virus in the central and eastern United States with the exception of Florida, and in urban areas elsewhere in the U.S.A. Cx. quinquefasciatus Say and Cx. pipiens L. have been incriminated as vectors of dog heartworm, Dirofilaria inimitis. Members of the complex may also be important pest mosquitoes, particularly in urban areas and in association with feed lots and farms.

GEOGRAPHIC DISTRIBUTION:

    The Culex pipiens complex in North America is represented by four members. In areas above 39 degrees N. latitude, only Culex pipiens, or the northern house mosquito, is usually encountered. At latitudes of less than 36 degrees N. only Cx. quinquefasciatus, the southern house mosquito, is generally present. Between 36 and 39 degrees N. latitudes, Cx. pipiens, Cx. quinquefasciatus, and hybrids between the two are encountered. The distribution o the fourth member, Cx. pipiens form molestus Forskal, remains poorly known.

BREEDING SITES, DEVELOPMENT, FLIGHT RANGE AND ASSOCIATED SPECIES:

    House mosquitoes are common in urban and suburban communities as well as on rural premises. Members of the complex readily breed in storm sewer catch basins, clean and polluted ground pools, ditches, animal waste lagoons, effluent from sewage treatment plants and other sites that are slightly to very eutrophic or polluted with organic wastes. Culex quinquefasciatus is generally associated with more eutrophic waters than Cx. pipiens. Females of Cx. pipiens and Cx. quinquefasciatus typically lay a single raft of 140-340 eggs after each bloodmeal. Eggs hatch in 1-2 days. Development from egg to adult is temperature dependent; requiring 8 to 12 days in summer. After bloodfeeding, females may return to the same or nearby larval habitats to oviposit and are often considered nonmigratory mosquitoes. However, females may travel considerable distances from resting sites to search for blood hosts, and marked females have been shown to travel up to 1100 m in a single night. Associated species include Cx. restuans, Cx. salinarius and Aedes albopictus in the eastern U.S., and Cx. tarsalis, Cx. restuans and Culiseta incidens in the western U.S.