Culex

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Culex
CPipFm.jpg
Culex pipiens female
Culex sp..jpg
Culex sp. male
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Culicidae
Subfamily: Culicinae
Tribe: Culicini
Genus: Culex
Linnaeus, 1758
Type species
Culex pipiens
Linnaeus, 1758
Diversity
Over 1,000 species
Anatomy of a Culex larva Culex restuans larva diagram en.svg
Anatomy of a Culex larva
Anatomy of a Culex adult Culex pipiens diagram en.svg
Anatomy of a Culex adult

Culex or typical mosquitoes are 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 such as West Nile virus, Japanese encephalitis, or St. Louis encephalitis, but also filariasis and avian malaria. They occur worldwide except for the extreme northern parts of the temperate zone, and are the most common form of mosquito encountered in some major U.S. cities, such as Los Angeles.

Contents

Etymology

In naming this genus, Carl Linnaeus used the nonspecific Latin term for a midge or gnat: culex . [1]

Description

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 forewings held horizontally over the abdomen when at rest. As in all Diptera capable of flight, the second pair of wings is reduced and modified into tiny, inconspicuous halteres.[ citation needed ]

Formal identification is important in mosquito control, but it is demanding and requires careful measurements of bodily proportions and noting the presence or absence of various bristles or other bodily features. [2]

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 have dappled or spotted wings, while culicine wings tend to be clear. 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. [3]

Life cycle

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 in rafts of as many as 300 on the water's surface. Suitable habitats for egg-laying are small bodies of standing fresh water: puddles, pools, ditches, tin cans, buckets, bottles, and water storage tanks (tree boles are suitable for only a few species). The tiny, cigar-shaped, dark brown eggs adhere to each other through adhesion forces, not any kind of cement, and are easily separated. Eggs hatch only in the presence of water, and the larvae are obligately aquatic, linear in form, and maintain their position and mostly vertical attitude in water by movements of their bristly mouthparts. To swim, they lash their bodies back and forth through the water. [4] [5]

During the larval stage, the insect lives submerged 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 larva, the pupa is comma-shaped. It does not feed, but can swim in rapid jerking motions to avoid potential predators. It must remain in regular contact with the surface to breathe, but it must not become desiccated. After 24–48 hours, the pupa ruptures and the adult emerges from the shed exoskeleton.[ citation needed ]

Vector of disease

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.[ citation needed ]

Nonanal has been identified as a compound that attracts Culex mosquitoes, perhaps pheromonally. [7] [8] [9] Nonanal acts synergistically with carbon dioxide. [10]

Diversity

Culex malariager, infected with the malarial parasite Plasmodium dominicana, in 15-20 million year old Dominican amber Culex malariager in Dominican amber.jpg
Culex malariager, infected with the malarial parasite Plasmodium dominicana, in 15–20 million year old Dominican amber

Culex is a diverse genus. It comprises over 20 subgenera that include a total of well over 1,000 species. Publications of newly described species are frequent.[ citation needed ]

Related Research Articles

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<span class="mw-page-title-main">West Nile fever</span> Human disease caused by West Nile virus infection

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<span class="mw-page-title-main">Arbovirus</span> Common name for several species of virus

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<i>Aedes aegypti</i> Species of mosquito

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The discipline of medical entomology, or public health entomology, and also veterinary entomology is focused upon insects and arthropods that impact human health. Veterinary entomology is included in this category, because many animal diseases can "jump species" and become a human health threat, for example, bovine encephalitis. Medical entomology also includes scientific research on the behavior, ecology, and epidemiology of arthropod disease vectors, and involves a tremendous outreach to the public, including local and state officials and other stake holders in the interest of public safety.

<span class="mw-page-title-main">London Underground mosquito</span> Species of fly

The London Underground mosquito is a form of mosquito in the genus Culex. It is found in the London Underground railway system as its name suggests, but has a worldwide distribution and long predates the existence of the London Underground. It was first described as a distinct species from Egyptian specimens by the biologist Peter Forsskål (1732–1763). He named this mosquito Culex molestus due to its voracious biting, but later biologists renamed it Culex pipiens f. molestus because there were no morphological differences between it and Culex pipiens. Notably, this mosquito assaulted Londoners sleeping in the Underground during the Blitz, although similar populations were long known.

<i>Culex pipiens</i> Species of fly

Culex pipiens is a species of mosquito commonly referred to as the common house mosquito or northern house mosquito, as it is the most common mosquito to the northern regions of the US. They can be found in both urban and suburban temperate and tropical regions across the world.

<i>Culex restuans</i> Species of fly

Culex restuans is a species of mosquito known to occur in Canada, the United States, Mexico, Guatemala, Honduras, and the Bahamas. It is a disease vector for St. Louis encephalitis and West Nile virus. In 2013 West Nile Virus positive specimens were collected in Southern California.

<span class="mw-page-title-main">Mosquito-borne disease</span> Diseases caused by bacteria, viruses or parasites transmitted by mosquitoes

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Kunjin virus (KUNV) is a zoonotic virus of the family Flaviviridae and the genus Flavivirus. It is a subtype of West Nile virus endemic to Oceania.

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<i>Culex quinquefasciatus</i> Species of fly

Culex quinquefasciatus, commonly known as the southern house mosquito, is a medium-sized mosquito found in tropical and subtropical regions of the world. It is a vector of Wuchereria bancrofti, avian malaria, and arboviruses including St. Louis encephalitis virus, Western equine encephalitis virus, Zika virus and West Nile virus. It is taxonomically regarded as a member of the Culex pipiens species complex. Its genome was sequenced in 2010, and was shown to have 18,883 protein-coding genes.

<i>Usutu virus</i> Species of virus

Usutu virus (USUV) is a flavivirus belonging to the Japanese encephalitis complex, which is an emerging zoonotic arbovirus of concern because of its pathogenicity to humans and its similarity in ecology with other emerging arboviruses such as West Nile virus. It mainly infects Culex mosquitoes and birds; humans form a dead-end host. First identified in South Africa in 1959, the virus has caused outbreaks in birds across Europe since 1996. Nearly 50 cases in humans have been reported as of 2019, mainly in Europe. These are predominantly asymptomatic, but some people experience neurological symptoms.

<i>Coquillettidia perturbans</i> Species of fly

Coquillettidia perturbans is a species of mosquito that have been documented in every continent except Antarctica. This mosquito is a known as a vector of West Nile virus and Eastern equine encephalomyelitis. The geographic range of C. perturbans is increasing due to the growing extensity of the feeding area. They are known to exist throughout the United States, mainly with a southern distribution, and are mammalophilic.

Hart Park virus, or HP virus, is a single-stranded RNA arbovirus that is primarily transmitted through mosquitoes. The HP virus is classified in the Rhabdoviridae family and is related to the viral agents that cause rabies and vesicular stomatitis. The exact date of discovery of this virus is uncertain, but its presence in the entomological community dates back as far as 1964. Because of its relatively recent discovery, its exact effect on hosts is uncertain. Currently, there is no known disease affiliated with the Hart Park virus.

<i>Anopheles sinensis</i> Species of mosquito

Anopheles sinensis is a species of mosquito that transmits malaria as well as lymphatic filariasis. It is regarded as the most important vector of these human parasitic diseases in Southeast Asia. It is the primary vector of vivax malaria in many regions. In China it also transmits the filalarial parasite, and arthropod roundworm. In Japan it is also a vector of a roundworm Setaria digitata in sheep and goats.

<i>West Nile virus</i> Species of flavivirus causing West Nile fever

West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family Flaviviridae, from the genus Flavivirus, which also contains the Zika virus, dengue virus, and yellow fever virus. The virus is primarily transmitted by mosquitoes, mostly species of Culex. The primary hosts of WNV are birds, so that the virus remains within a "bird–mosquito–bird" transmission cycle. The virus is genetically related to the Japanese encephalitis family of viruses. Humans and horses both exhibit disease symptoms from the virus, and symptoms rarely occur in other animals.

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<i>Culex nigripalpus</i> Species of mosquito

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References

  1. "culex". dictionary.com . Retrieved 2011-07-06.
  2. Harbach, Ralph. "Culex Mosquito Taxonomic Inventory".
  3. "Entomology and Acarology: Difference between Anopheline and Culicine mosquitoes". ecoursesonline.iasri.res.in.
  4. "Mosquito Ecology and Surveillance Laboratory" . Retrieved 7 August 2014.
  5. Mike Service (21 February 2008). Medical Entomology for Students. Cambridge University. pp. 53–54. ISBN   978-0-521-70928-6.
  6. Moraes, Priscilla (March 27, 2016). "Brazilian experts investigate if 'common mosquito' is transmitting zika virus" . Retrieved 2016-03-07.
  7. "UC Davis Researchers Identify Dominant Chemical That Attracts Mosquitoes to Humans". University of California, Davis. October 26, 2009. Retrieved 2011-07-06.
  8. Syed, Z.; Leal, W. S. (2009). "Acute olfactory response of Culex mosquitoes to a human- and bird-derived attractant". Proceedings of the National Academy of Sciences. 106 (44): 18803–18808. Bibcode:2009PNAS..10618803S. doi: 10.1073/pnas.0906932106 . PMC   2767364 . PMID   19858490.
  9. Hill, Sharon R.; Hansson, Bill S.; Ignell, Rickard (January 15, 2009). "Characterization of Antennal Trichoid Sensilla from Female Southern House Mosquito, Culex quinquefasciatus Say". Chemical Senses. 34 (3): 231–252. CiteSeerX   10.1.1.319.1429 . doi:10.1093/chemse/bjn080. PMID   19153252.
  10. "Scientists Identify Key Smell that Attracts Mosquitoes to Humans". U.S. News & World Report . October 28, 2009. Retrieved 2011-07-06.