Culex pipiens,
house mosquito

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Taxonomic lineage

cellular organisms - Eukaryota - Fungi/Metazoa group - Metazoa - Eumetazoa - Bilateria - Coelomata - Protostomia - Panarthropoda - Arthropoda - Mandibulata - Pancrustacea - Hexapoda - Insecta - Dicondylia - Pterygota - Neoptera - Endopterygota - Diptera - Nematocera - Culicimorpha - Culicoidea - Culicidae - Culicinae - Culicini - - Culex - Culex pipiens complex - Culex pipiens

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Brief facts

• Culex mosquitos are the most widely distributed mosquito in the world. The most important of the Culex vectors are members of the Culex pipiens complex, a very closely related group of species (or incipient species - the taxonomy remains unclear) that originated in Africa but has spread by human activity to tropical and temperate climate zones on all continents but Antarctica.
• Culex pipiens mosquitos are important vectors of human pathogens in the United States and world-wide. They carry a number of devastating diseases such as St. Louis encephalitis (SLE), West Nile encephalitis, Eastern equine encephalitis, Venezuelan equine encephalitis, Japanese encephalitis, Ross River encephalitis, Murray Valley encephalitis, Rift valley fever, and lymphatic filariases. Culex mosquitos are competent to transmit heartworms. Detailed information about ubiquitous parasites - heartworms, Dirofilaria immitis at MetaPathogen.
• Culex pipiens is normally considered to be a bird feeder but some urban strains have a predilection for mammalian hosts and feed readily on humans.
• The genome sequence of a member of the Cx. pipiens complex will greatly simplify the identification of mosquito genes required for pathogen transmission, potentially enabling the development of new strategies for combating and controlling these diseases.

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Life cycle of Culex pipiens

Life Cycle Stages

Life cycle of Culex pipiens represents a variation of the the multivoltine life cycle (according to a classification system for Northeastern mosquito life cycles): non-desiccation resistant eggs laid directly on water; larvae develop in polluted water habitats; multiple generations each year; overwinters as a mated female.

• egg Culex mosquitoes lay their eggs usually at night on the surface of fresh or stagnant water; usually lay their eggs at night; a mosquito may lay a raft of eggs every third night during its life span; Culex mosquitoes lay their eggs one at a time, sticking them together to form a raft of from 200-300 eggs; a raft of eggs looks like a speck of soot floating on the water and is about 1/4 inch long and 1/8 inch wide
  • embryo
• hatching larval
  MeSH commonly called wigglers; all larval stages are aquatic; collectively they take from 7 to 14 days to complete
  • 1st instar larva
  • 1st molting
  • 2nd instar larva
  • 2nd molting
  • 3rd instar larva
  • 3rd molting
  • 4th instar larva
  • 4th molting
• pupa MeSH commonly called tumblers; pupal stage takes 2 days to several weeks to complete
• newly eclosed
• adult Culex usually live only a few weeks during the warm summer months; those females which emerge in late summer search for sheltered areas where they hibernate (diapause) until spring; warm weather brings them out in search of water on which to lay their eggs

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West Nile virus transmizssion cycle

Aaron C. Brault. Changing patterns of West Nile virus transmission: altered vector competence and host susceptibility Vet Res. 2009 Mar–Apr; 40(2): 43.

Transmission cycles of WNV. Transmission occurs between ornithophilic mosquito species (Culex spp.) and passeriform avian hosts. Birds typically manifest high viremias capable of exceeding oral infection thresholds for many mosquito vectors. Humans and equines fail to generate sufficient viremia for the infection of mosquito hosts and are deemed "dead end" or tangential hosts. Red: Avian mortality was first identified in a migratory stork and subsequently in commercially farmed geese in the late 1990s and has subsequently been associated with widespread mortality among numerous North American avian species (in particular, corvids).

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Liza Gross. A New Model for Predicting Outbreaks of West Nile Virus PLoS Biol. 2006 April; 4(4): e101.

A shift in the feeding behavior of Culex mosquitoes (their larvae amass in standing water, as seen above) helps explain the rising incidence of West Nile virus in North America. (Image: James Gathany, CDC)

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