London Underground mosquito

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London Underground mosquito
Culex Molestus.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Culicidae
Genus: Culex
Species:
C. molestus
Binomial name
Culex molestus
Forskal, 1775

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. [1] It was first described as a distinct species from Egyptian specimens by the biologist Peter Forsskål (1732–1763). [2] 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. [2] Notably, this mosquito assaulted Londoners sleeping in the Underground during the Blitz, [3] although similar populations were long known. [1]

Contents

A study from 2004 analyzing DNA microsatellites suggested that Culex molestus is likely a distinct species from Culex pipiens. [1] However, a more recent paper from 2012 argues that it is more accurately "a physiological and ecological variant of Cx. pipiens" and should not be considered a distinct species. [4]

Description

Londoners sheltering from the Blitz in underground stations suffered from mosquito bites Blitz West End Air Shelter.jpg
Londoners sheltering from the Blitz in underground stations suffered from mosquito bites

This mosquito, first identified in Egypt in the late 18th century, [1] has been found in underground systems around the world. Some authors suggested that it adapted to human-made underground systems since the last century from local above-ground Culex pipiens , [3] [5] but the more recent evidence suggests it is a southern mosquito variety related to C. pipiens that has adapted to the warm underground spaces of northern cities. [1]

Behavioral evidence for this mosquito being a different species from C. pipiens comes from research by Kate Byrne and Richard Nichols. The species have very different behaviours, [3] are extremely difficult to mate, [5] and with different allele frequencies consistent with genetic drift during a founder event. [6] More specifically, this mosquito, C. molestus, breeds all-year round, is cold intolerant, and bites rats, mice, and humans, in contrast to the above-ground species, which is cold tolerant, hibernates in the winter, and is considered to mostly feed on bird hosts. When the two varieties were crossbred, the eggs were infertile, suggesting reproductive isolation. [3] [5]

Hosts

The mosquito has been documented to feed upon birds. [7]

Parasites

For decades Cx. molestus was known only as a fully competent host of one kind of malaria, Plasmodium garnhami . [7] Only this Plasmodium had been demonstrated to complete sporogony by Garnham 1966. [7] Due to this lack of study a team investigated whether a more common kind of malaria could also go through the life cycle. [7] Žiegytė et al. 2014 find that P. relictum also completes sporogony in Cx. molestus. [7] They also discovered that two P. relictum strains differing only by one base pair produced markedly different parasitemia of the insect; pGRW11 much more than pSGS1. [7]

Heredity

Genetic data indicate the molestus form in the London Underground appear to have a common ancestry, rather than the population at each station being related to the nearest above-ground population. Byrne and Nichols' working hypothesis was that adaptation to the underground environment had occurred locally in London once only – many hurdles must be overcome to become adapted to the subterranean environment, and understandably it would occur rarely. This hypothesis implies that local adaptation would be expected in different locations around Europe and beyond, as each local population evolved an offshoot that overcame the problems of living underground.

However, more recently collected genetic evidence reported by Fonseca and others suggests a single C. molestus form has spread throughout Europe and beyond, since populations over a large area share a common genetic heritage. These widely separated populations are distinguished by very minor genetic differences, which suggest the underground form developed recently; a single mtDNA difference is shared among the underground populations of 10 Russian cities, [8] and a single fixed microsatellite difference occurs in populations spanning Europe, Japan, Australia, the Middle East, and the Atlantic islands. [1] This worldwide spread might have occurred after the last glaciations or may be even more recent, due to the insects hitchhiking on world trade routes; one possibility is the international secondhand tire trade. The tires retain water in which the larvae can survive, and completely removing water from an old tire can be difficult.

Also, the Fonseca paper obtained genetic evidence that the recent colonization of America by Culex mosquitoes actually involves a strain derived from a rare successful hybridization between C. pipiens and C. molestus. They suggest hybridization may explain why the American form bites both birds and humans (this interpretation is controversial, see letter from Spielman et al. [9] and the response that follows it in Science ). The consequences of this more indiscriminate feeding hit the news in 1999 with the outbreak of human encephalitis in New York, caused by West Nile virus. It was the first documented introduction of this virus into the Western Hemisphere; perhaps because in the longer established populations, the Old World northern above-ground C. pipiens almost exclusively bites birds, with the human-biting ones being incarcerated below ground.

Distribution

Culex molestus has been observed in North and South America, Europe, Asia, Africa, and Australasia. It was first described in Egypt in the late 1700s, [10] and has likely spread via trade and colonial passages over the past centuries.

In the summer of 2011, an invasion of Culex molestus appeared on the Upper West Side in Manhattan, New York City. The mosquito is well known for being commonly found in sewers of New York and thriving throughout the year feeding on humans. Residents of older brownstones found the mosquitoes coming into basements and then through air vents and other openings into their homes. The city government did not make this infestation of the pest a top priority because they tested negative for West Nile virus and because of the high cost of mosquito control. [11]

In Australia, Culex molestus was first recorded in the 1940s, and has since spread across all southern states, causing a significant biting nuisance in urban areas. Unlike most Australian urban mosquitos, molestus is active through all 12 months of the year. Its introduction was likely through military movements into Melbourne during World War II, and genetic studies have indicated its most likely passage was from eastern Asia and Japan. [12] It has also been identified as a potential vector for several Australian blood-borne diseases, such as Ross River virus.

Related Research Articles

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

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 people, encephalitis or meningitis occurs, with associated neck stiffness, confusion, or seizures. Recovery may take weeks to months. The risk of death among those in whom the nervous system is affected is about 10 percent.

<i>Plasmodium</i> Genus of parasitic protists that can cause malaria

Plasmodium is a genus of unicellular eukaryotes that are obligate parasites of vertebrates and insects. The life cycles of Plasmodium species involve development in a blood-feeding insect host which then injects parasites into a vertebrate host during a blood meal. Parasites grow within a vertebrate body tissue before entering the bloodstream to infect red blood cells. The ensuing destruction of host red blood cells can result in malaria. During this infection, some parasites are picked up by a blood-feeding insect, continuing the life cycle.

<i>Wolbachia</i> Genus of bacteria in the Alphaproteobacteria class

Wolbachia is a genus of gram-negative bacteria that can either infect many species of arthropod as an intracellular parasite, or act as a mutualistic microbe in filarial nematodes. It is one of the most common parasitic microbes of arthropods, and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex. Some host species cannot reproduce, or even survive, without Wolbachia colonisation. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70% of all insect species are estimated to be potential hosts.

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

Aedes aegypti, the yellow fever mosquito, is a mosquito that can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito can be recognized by black and white markings on its legs and a marking in the form of a lyre on the upper surface of its thorax. This mosquito originated in Africa, but is now found in tropical, subtropical and temperate regions throughout the world.

Plasmodium relictum is a species in the genus Plasmodium, subgenus Haemamoeba.

<span class="mw-page-title-main">Avian malaria</span> Parasitic disease of birds

Avian malaria is a parasitic disease of birds, caused by parasite species belonging to the genera Plasmodium and Hemoproteus. The disease is transmitted by a dipteran vector including mosquitoes in the case of Plasmodium parasites and biting midges for Hemoproteus. The range of symptoms and effects of the parasite on its bird hosts is very wide, from asymptomatic cases to drastic population declines due to the disease, as is the case of the Hawaiian honeycreepers. The diversity of parasites is large, as it is estimated that there are approximately as many parasites as there are species of hosts. As research on human malaria parasites became difficult, Dr. Ross studied avian malaria parasites. Co-speciation and host switching events have contributed to the broad range of hosts that these parasites can infect, causing avian malaria to be a widespread global disease, found everywhere except Antarctica.

<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

Mosquito-borne diseases or mosquito-borne illnesses are diseases caused by bacteria, viruses or parasites transmitted by mosquitoes. Nearly 700 million people get a mosquito-borne illness each year, resulting in over 725,000 deaths.

Plasmodium juxtanucleare is a species of parasite in the family Plasmodiidae. The vertebrate hosts for this parasite are birds.

Rocio viral encephalitis is an epidemic flaviviral disease of humans first observed in São Paulo State, Brazil, in 1975. Low-level enzootic transmission is likely continuing in the epidemic zone, and with increased deforestation and population expansion, additional epidemics caused by Rocio virus are highly probable. If migratory species of birds are, or become involved in, the virus transmission cycle, the competency of a wide variety of mosquito species for transmitting Rocio virus experimentally suggest that the virus may become more widely distributed. The encephalitis outbreak in the western hemisphere caused by West Nile virus, a related flavivirus, highlights the potential for arboviruses to cause severe problems far from their source enzootic foci.

<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.

<span class="mw-page-title-main">Mesoniviridae</span> Family of viruses

Mesoniviridae is a family of enveloped, positive-strand RNA viruses in the order Nidovirales which infect mosquitoes. The family is named after the size of the genomes relative to other nidoviruses, with meso- coming from the Greek word mesos, which means medium, and -ni being an abbreviation of nido.

Culex vishnui is a mosquito belonging to the Culicidae family. It is the most common vector (carrier) of the Japanese encephalitis virus (JEV) in India, Sri Lanka, Thailand, and Sarawak.

<span class="mw-page-title-main">Thorselliaceae</span> Genus of bacteria

Thorselliaceae is a family of bacteria belonging to the class Gammaproteobacteria and it was first described in February 2015. It is not assigned to an order. The family consists of four species in two genera. The bacteria are Gram-negative and rod shaped, approximately 1 μm wide and 2 μm long. They are facultative anaerobes and motile. Thorselliaceae bacteria have been found around the world associated with vector mosquitoes, mainly with vectors of malaria.

<i>Aedes koreicus</i> Species of fly

Commonly known as the Korean bush mosquito, Ae. koreicus adults are relatively large with a black and white pattern on their legs and other body parts. Clear longitudinal lines on the dorsal part of the thorax distinguish it from Ae. aegypti and Ae. albopictus. The species bears close morphological, ecological, and genetic similarity to the Asian bush mosquito, Aedes japonicus, but can be physically distinguished by a pale basal band on the hind tarsomere.

<i>Culiseta annulata</i> Species of mosquito

Culiseta annulata is a species of mosquito in the family Culicidae. It is found in the Palearctic.

Plasmodium homonucleophilum is a parasitic apicomplexan of the genus Plasmodium, subgenus Novyella whose parasitic hosts are birds.

References

  1. 1 2 3 4 5 6 Fonseca DM, Keyghobadi N, Malcolm CA, et al. (March 2004). "Emerging vectors in the Culex pipiens complex" (PDF). Science. 303 (5663): 1535–1538. Bibcode:2004Sci...303.1535F. doi:10.1126/science.1094247. PMID   15001783. S2CID   40158868. Archived from the original (PDF) on 23 July 2011.
  2. 1 2 Lõhmus, Mare; Lindström, Anders; Björklund, Mats (2 August 2012). "How often do they meet? Genetic similarity between European populations of a potential disease vector Culex pipiens". Infection Ecology & Epidemiology. 2 (1): 12001. Bibcode:2012InfEE...212001L. doi:10.3402/iee.v2i0.12001. PMC   3426333 . PMID   22957132.
  3. 1 2 3 4 Burdick, Alan (February 2001). "Insect From the Underground" (PDF). Natural History . Vol. 101, no. 1. p. 86.
  4. ↑ Harbach, Ralph (December 2012). "Culex pipiens: Species Versus Species Complex – Taxonomic History and Perspective". Journal of the American Mosquito Control Association. 28 (4s): 10–23. doi:10.2987/8756-971X-28.4.10. PMID   23401941. S2CID   31007129.
  5. 1 2 3 "London underground source of new insect forms". The Times . 26 August 1998.
  6. ↑ Byrne K, Nichols RA (January 1999). "Culex pipiens in London Underground tunnels: differentiation between surface and subterranean populations". Heredity. 82 (1): 7–15. doi: 10.1038/sj.hdy.6884120 . PMID   10200079.
  7. 1 2 3 4 5 6
  8. ↑ Vinogradova EB, Shaikevich EV (2007). "Morphometric, physiological and molecular characteristics of underground populations of the urban mosquito Culex pipiens Linnaeus f. molestus Forskål (Diptera: Culicidae) from several areas of Russia". European Mosquito Bulletin. 22: 17–24. ISSN   1460-6127.
  9. ↑ Spielman A, Andreadis TG, Apperson CS, et al. (November 2004). "Outbreak of West Nile virus in North America". Science. 306 (5701): 1473c–1475c. doi:10.1126/science.306.5701.1473c. PMID   15567836. S2CID   8773766.
  10. ↑ A Kassim, Nur Faeza; Webb, Cameron E; Wang, Qinning; Russell, Richard C (August 2013). "Australian distribution, genetic status and seasonal abundance of the exotic mosquito Culex molestus (Forskal) (Diptera: Culicidae): Culex molestus in Australia". Australian Journal of Entomology . 52 (3): 185–198. doi:10.1111/aen.12021.
  11. ↑ Carlin, Dave (3 November 2011). "Exclusive: Upper West Side Mosquito Mystery". CBS New York. CBS Local Media. Retrieved 4 November 2011.
  12. ↑ Kassim N, Webb C, Wang Q, Russell R (August 2013). "Australian distribution, genetic status and seasonal abundance of the exotic mosquito Culex molestus (Forskal)". Australian Journal of Entomology. 52 (3): 185–98. doi:10.1111/aen.12021.
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