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''Culex'' is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...
es, 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 Arbovirus is an informal name for any virus that is transmitted by arthropod vectors. The term ''arbovirus'' is a portmanteau word (''ar''thropod-''bo''rne ''virus''). ''Tibovirus'' (''ti''ck-''bo''rne ''virus'') is sometimes used to more spe ...
infections such as
West Nile virus 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 ...
,
Japanese encephalitis Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV). While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases, symptoms may include he ...
, or
St. Louis encephalitis Saint Louis encephalitis is a disease caused by the mosquito-borne Saint Louis encephalitis virus. Saint Louis encephalitis virus is related to Japanese encephalitis virus and is a member of the family ''Flaviviridae''. This disease mainly affe ...
, but also
filariasis Filariasis is a parasitic disease caused by an infection with roundworms of the Filarioidea type. These are spread by blood-feeding insects such as black flies and mosquitoes. They belong to the group of diseases called helminthiases. These ...
and
avian malaria Avian malaria is a parasitic disease of birds, caused by parasite species belonging to the genera '' Plasmodium'' and '' Hemoproteus'' (phylum Apicomplexa, class Haemosporidia, family Plasmoiidae). The disease is transmitted by a dipteran vecto ...
. They occur worldwide except for the extreme northern parts of the
temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
, and are the most common form of mosquito encountered in some major U.S. cities, such as
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...
.


Etymology

In naming this
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
,
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
appropriated the nonspecific
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
term for a midge or gnat: '.


Description

Depending on the species, the adult ''Culex'' mosquito may measure from . The adult morphology is typical of flies in the suborder
Nematocera The Nematocera (the name means "thread-horns") are a suborder of elongated flies with thin, segmented antennae and mostly aquatic larvae. This group is paraphyletic and contains all flies but species from suborder Brachycera (the name means "sh ...
with the
head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...
,
thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
, and
abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
clearly defined and the two
forewings Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments (the mesothorax and metathorax), and the two pairs are often referred to as the forewings and hindwi ...
held horizontally over the abdomen when at rest. As in all
Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
capable of flight, the second pair of wings is reduced and modified into tiny, inconspicuous
halteres ''Halteres'' (; singular ''halter'' or ''haltere'') (from grc, ἁλτῆρες, weights held in the hands to give an impetus in leaping) are a pair of small club-shaped organs on the body of two orders of flying insects that provide infor ...
. 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. 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.


Lifecycle

The developmental cycle of most species takes about two weeks in warm weather. The
metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
is typical of
holometabolism Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the superorder Endopterygot ...
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. During the larval stage, the insect lives submerged in water and feeds on particles of organic matter, microscopic organisms or plant material; after several
instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
s it then develops into a
pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
. 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.


Diseases from culex

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. * Cat Que Virus (CQV) has been largely reported in Culex mosquitoes in China and in pigs in Vietnam. For CQV, domestic pigs are considered to be the primary mammalian hosts. Antibodies against the virus have been reported in swine reared locally in China. *
Arbovirus Arbovirus is an informal name for any virus that is transmitted by arthropod vectors. The term ''arbovirus'' is a portmanteau word (''ar''thropod-''bo''rne ''virus''). ''Tibovirus'' (''ti''ck-''bo''rne ''virus'') is sometimes used to more spe ...
infections transmitted by various species of ''Culex'' include West Nile virus, Japanese encephalitis, St. Louis encephalitis, and Western and Eastern equine encephalitis.
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
ian scientists are investigating if ''Culex'' species transmit
zika virus ''Zika virus'' (ZIKV; pronounced or ) is a member of the virus family ''Flaviviridae''. It is spread by daytime-active ''Aedes'' mosquitoes, such as '' A. aegypti'' and '' A. albopictus''. Its name comes from the Ziika Forest of Uganda, whe ...
. *
Nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
infections, mainly forms of
filariasis Filariasis is a parasitic disease caused by an infection with roundworms of the Filarioidea type. These are spread by blood-feeding insects such as black flies and mosquitoes. They belong to the group of diseases called helminthiases. These ...
may be borne by ''Culex'' species, as well as by other mosquitoes and bloodsucking flies. *
Protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...
parasites in the phylum
Apicomplexa The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. T ...
, such as various forms of
avian malaria Avian malaria is a parasitic disease of birds, caused by parasite species belonging to the genera '' Plasmodium'' and '' Hemoproteus'' (phylum Apicomplexa, class Haemosporidia, family Plasmoiidae). The disease is transmitted by a dipteran vecto ...
The ''Culex pipiens pipiens'' bioform of ''
Culex pipiens ''Culex pipiens'', commonly referred to as the common house mosquito, is a species of mosquito. House mosquitoes are some of the most common mosquitoes in the United States. More specifically, ''Culex pipiens'' is considered as the northern hous ...
'' usually inhabits areas above ground and targets avian species. The ''
Culex pipiens molestus The London Underground mosquito is a form (zoology), 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 Lo ...
'' bioform, on the other hand, usually inhabits underground cavities and targets human hosts. When these two bioforms hybridize, the progeny shows depolarization in both habitat and host preferences. As a result, these hybridized species play a role in disease transmission. This is because avian species amplify diseases such as West Nile virus. A hybridized mosquito can become infected by feeding on an avian amplifier and then feed on a human, effectively passing on West Nile pathogens to that human.
Nonanal Nonanal, also called nonanaldehyde, pelargonaldehyde or Aldehyde C-9, is an aldehyde. A colourless, oily liquid, nonanal is a component of perfumes. Although it occurs in several natural oils, it is produced commercially by hydroformylation of 1- ...
has been identified as a compound that attracts ''Culex'' mosquitoes, perhaps pheromonally. Nonanal acts synergistically with
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
.


Diversity

''Culex'' is a diverse genus. It comprises over 20
subgenera In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
that include a total of well over 1,000 species. Publications of newly described species are frequent.


References


External links

* On the UF / IFAS Featured Creatures Web site *
''Culex'' (''Culex'') ''nigripalpus'' Theobald
*

*


''Culex pipiens'' at MetaPathogen: facts, life cycle


in the National Public Health Pesticide Applicator Training Manual {{Taxonbar, from=Q276595 Mosquito genera Insect vectors of human pathogens Taxa named by Carl Linnaeus