''Culex quinquefasciatus'' (originally named ''Culex fatigans''), commonly known as the southern house mosquito, is a medium-sized mosquito found in

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

regions of the world. It is a

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

of ''

Wuchereria bancrofti ''Wuchereria bancrofti'' is a filarial (arthropod-borne) nematode (roundworm) that is the major cause of lymphatic filariasis. It is one of the three parasitic worms, together with ''Brugia malayi'' and '' B. timori'', that infect the lymphati ...

'', avian malaria, and arboviruses including St. Louis encephalitis virus, Western equine encephalitis virus,

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, where ...

and

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 ...

. 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.

Etymology

American entomologist

Thomas Say Thomas Say (June 27, 1787 – October 10, 1834) was an American entomologist, conchologist, and Herpetology, herpetologist. His studies of insects and shells, numerous contributions to scientific journals, and scientific expeditions to Florida, Ge ...

described ''Culex quinquefasciatus'', which he collected along the

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

, in 1823. Originally written as "C. 5-fasciatus", the name refers to five (''quinque'') black, broad, transverse bands ("fasciatus" or "fasciae") on the mosquito's dorsal abdomen. The name remains despite later revelations of more than five fasciae, thanks to improved microscopy. Although ''quinquefasciatus'' is the official scientific name, there are at least five synonymous names for this species.

Taxonomy

''Cx. quinquefasciatus'' is a member of the ''Culex pipiens'' species complex. Smith et al. 2004 develop an assay specifically for this complex and use it to confirm that it does encompass this species.

Description

The adult ''C. quinquefasciatus'' is a medium-sized mosquito and is brown in colour. The body is about 3.96 to 4.25 mm long. While the main body is brown, the

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular arthropod mouthparts, mouthparts used for feeding and sucking. In vertebrates, a pr ...

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of 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 di ...

, wings, and tarsi are darker than the rest of the body. 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 ani ...

is light brown, with the lightest portion in the center. The antennae and the proboscis are about the same length, but in some cases, the antennae are slightly shorter than the proboscis. The

flagellum A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

has 13 segments that may have few or no scales. The scales of the thorax are narrow and curved. The

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

has pale, narrow, rounded bands on the basal side of each

tergite A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Anterior ...

. Males can be differentiated from females in having large palps and feathery antennae. The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

has a short and stout head. The mouth brushes have long yellow filaments used for filtering organic materials. The abdomen consists of eight segments, the

siphon A siphon (; also spelled syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, abo ...

, and the

saddle A saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not know ...

. Each segment has a unique

seta In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...

e pattern. The siphon is on the dorsal side of the abdomen, and is four times longer than its breadth. The siphon has multiple setae tufts. The saddle is barrel-shaped and located on the ventral side of the abdomen, with four long anal papillae protruding from the posterior end.

Lifecycle

Mature ''C. quinquefasciatus'' females fly at night to nutrient-rich standing water to lay eggs. They breed profusely in dirty water collections, including stagnant drains, cesspools, septic tanks with leaks, burrow pits, and almost all organic polluted water collections. A single female can lay up to five rafts of eggs in a lifetime, with each raft containing 100 to 300 eggs. The exact number varies depending on climatic conditions. The larvae feed on organic material in the water and require between five and eight days to complete their development at . The larvae pass through four larval

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

s, and towards the end of the fourth instar, they stop eating and undergo moulting to give rise to

pupa A pupa (; : 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 life cycle, the stages th ...

e. After 36 hours at , adults emerge. The exact timing of development can vary depending on temperature. In optimum temperature and humidity, the lifecycle will be completed in seven days, passing through the egg, larval, pupal, and adult stages. Both male and female adults take sugar meals from plants. After mating, the female seeks a blood meal from a mammal or bird, as ingested blood is necessary for egg development. ''C. quinquefasciatus'' shows a preference for the blood of birds, but will also commonly bite humans.

Hosts

Known hosts include

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s (Aves),

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

(''Bos taurus)'',

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. ...

s (''Canis familiaris)'', '' Equus'' including

donkey The donkey or ass is a domesticated equine. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as a separate species, ''Equus asinus''. It was domes ...

s (''E. asinus)'',

cat The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

s (''Felis)'',

mice A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

(''Mus musculus)'',

house sparrow The house sparrow (''Passer domesticus'') is a bird of the Old World sparrow, sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pa ...

s (''Passer domesticus)'',

rats Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' (pack rats), '' Bandicota'' (bandicoot ...

(''Rattus)'' and

boars The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a Suidae, suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The speci ...

(''Sus scrofa)''.

Distribution

"Quinx" are among the world's most abundant peridomestic mosquitoes, earning the nickname "southern house mosquito". The species' place of origin is uncertain. It may have been native to the lowlands of West Africa, or to Southeast Asia. ''Cx. quinquefasciatus'' is now found throughout subtropical and tropical areas worldwide, including the Americas, Australia and New Zealand, except for exceedingly dry or cold regions. Thomas Say described the species as "exceedingly numerous and troublesome". It rests in trees and high places.

As a vector

The southern house mosquito is a principal vector of numerous pathogens, transmitting the phlebovirus Rift Valley fever virus, and the two flaviviruses St. Louis encephalitis virus and West Nile virus, plus filarial worms and avian malarial parasites. It transmits

zoonotic diseases A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (b ...

that affect humans and wild and domestic animals, such as

lymphatic filariasis Lymphatic filariasis is a human disease caused by parasitic worms known as filarial worms. Usually acquired in childhood, it is a leading cause of permanent disability worldwide, impacting over a hundred million people and manifesting itself in ...

, avian malaria, St. Louis encephalitis,

Western equine encephalitis Western equine encephalitis virus is the causative agent of the relatively uncommon viral disease Western equine encephalitis (WEE). An alphavirus of the family ''Togaviridae'', the WEE virus is an arbovirus (arthropod-borne virus) transmitted b ...

, and

West Nile fever West Nile fever is an infection by the West Nile virus, which is typically spread by mosquitoes. In about 80% of infections people have few or no symptoms. About 20% of people develop a fever, headache, vomiting, or a rash. In less than 1% of ...

, and may be a

of the

.Kathy Keatley Garvey. 2016.
Are Culex Mosquitoes Potential Vectors of the Zika Virus?
, Bug Squad, Happenings in the Insect World, March 2, 2016. It causes infection through biting during blood meal. In the southern U.S., it is the primary vector of St. Louis encephalitis virus. In India and Southeast Asia, it is the primary vector of ''

'', a nematode that causes

. It acts as an intermediate host for the helminth parasite by harbouring the larval stages. In

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, it is the principal vector of avian malaria (''

Plasmodium relictum ''Plasmodium relictum'' is a species in the genus ''Plasmodium,'' subgenus '' Haemamoeba''. It is a parasite, and the most common cause of malaria in birds. Like all ''Plasmodium'' species, ''P. relictum'' has both vertebrate and insect hosts. ...

),'' to which historic extinctions and significant contemporary population declines in Hawaii's native

honeycreeper The true honeycreepers form a genus ''Cyanerpes'' of small birds in the tanager family Thraupidae. They are found in the tropical New World from Mexico south to Brazil. They occur in the forest canopy, and, as the name implies, they are specialis ...

species are attributed. It is the definitive host for the malarial parasite as it harbours the sexual cycle. In 2013 West Nile Virus positive specimens were collected in Southern California. Now, people have to stop the invasive spread to save the native birds.

References

External links

* * *
Disease monger

Identification guide at University of Florida

Taxonomy at UniProt
{{Authority control quinquefasciatus Insects described in 1823 Insect vectors of pathogens