Culex
| Culex | ||||||||||||
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Males and females of a Culex species |
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| Scientific name | ||||||||||||
| Culex | ||||||||||||
| Linnaeus , 1758 |
Culex ( Latin cúlex, -icis , "mosquito") is a species-rich genus withinthe mosquito family (Culicidae). To date, the 768 species are known, 16 of whichare nativeto Europe . The most well-known Central European species is the common mosquito ( Culex pipiens ). Some species of the genus are carriers of disease-causing viruses such as the West Nile virus .
features
The animals reach a body length of four to ten millimeters. Like all mosquitoes, the females have a proboscis in contrast to the males . The four-membered, rarely five-membered palps reach about a quarter of the length of the trunk. The feelers are usually a little longer than this. The mesonotum of the thorax is slightly to strongly curved. This and the scutellum are usually covered with narrow scales, rarely those of the scutellum are wide. The postnotum is scaly and hairless. The pleura on the sides of the thorax are scaled differently depending on the type, often this scaling is also reduced. The legs are narrow and long, all three pairs have four tarsal links. The tergites and sternites two to seven of the abdomen are covered with large scales. The end of the abdomen is blunt.
The males of different species differ particularly in the length of the palps, which can be about the same length as the proboscis up to a quarter as long. The antennae are about the same length as the proboscis. Unlike the females, the front and middle pairs of legs have strong claws. Those of the hind legs are the same, like the females, very small.
The larvae have an elongated body with a large head, slightly wider than it is long, and a thorax that is very broad compared to the abdomen. The antennae are usually long and almost always have hairs. The larvae differ from those of similar genera by the number of hairs on the thorax and abdomen and by the shape of their breathing tube. This is medium to long, sometimes very long, only rarely short. The trachea are well developed. The tuft of hair that sits on the last, eighth segment of the abdomen, usually has four pairs of hair, only the genus Acallyntrum has one or no pair.
Way of life
In the majority of species, females suckle blood from mammals , such as humans. Some of these species also sting birds at the same time . Others only specialize in birds, frogs, or lizards .
The females usually lay their eggs in small boats on the surface of the water. Some species lay their eggs on leaf axils or in knotholes and the like, but also in man-made water holes, such as rain barrels. The species that lay their eggs on the leaf axils lay their eggs individually wrapped in a gelatinous layer. The larvae hatch after a few days.
Systematics
The genus Culex is classified together with Deinocerites in the tribe Culicini and is currently divided into 24 subgenera. The genus occurs worldwide, some species were also transported to other parts of the world by humans. But there are also a number of Culex species that are endemic to only small areas - such as islands in the Pacific.
Culex as a disease vector
The feeding of females with blood from various vertebrates also leads to the ingestion of pathogens if they circulate in the bloodstream of the vertebrate during a short phase of the disease or are permanently present in the event of a chronic infection (e.g. viraemia ). The pathogens that alternate between insects and vertebrates - mostly viruses - are resistant to the mosquito's digestive enzymes and can in some cases also multiply in the adult insect. The digestive tract of the species Culex inactivates viruses far less than the related genus Aedes , so that some viruses can only replicate in Culex species (e.g. the Sindbis virus ).
The pathogens can also be transmitted from the female to the eggs through a so-called vertical transmission and then replicate in the mosquito larvae. This vertical transmission enables some species of Culex to transmit viruses as early as the first meal of blood. Typically, these viruses, known as arboviruses , circulate between mosquitoes and different species of animals without causing disease in either. Humans are usually a false host of the pathogen, which can, however, lead to disease.
The pathogens transmitted by species of the genus Culex include a large number of viruses which, due to their transmission by arthropods, belong to the epidemiological group of the arboviruses. The Culex spp. transmitted arboviruses include pathogens causing encephalitis such as West Nile fever ( Culex pipiens ), Japanese encephalitis , St. Louis encephalitis ( C. nigripalpus, C. pipiens, C. tarsalis ), Kunjin encephalitis ( C. annulirostris ) and causative agents of milder febrile illnesses such as Chikungunya virus , Sindbis virus ( C. pipiens, C. univittatus ), Tahyna virus and Ross River virus .
But also roundworms like Wuchereria bancrofti (pathogen of a lymphatic filariasis ) and Brugia malayi are transmitted by Culex species. These pathogens go through various stages of development between the mosquito and the host. In the Culex mosquitoes that metacyclic third instar larvae of nematodes migrate into the pricking bristle sheath the mosquito to actively penetrate from there when Saugakt into the host.
supporting documents
Individual evidence
- ^ Erwin J. Hentschel & Günther H. Wagner: Zoological dictionary . Gustav Fischer Verlag, Jena 1996, ISBN 3-334-60960-X .
- ^ Subfamily Culicinae Meigen, 1818. RE Harbach: Mosquito Taxonomic Inventory, accessed July 30, 2012 .
- ^ Culex. (No longer available online.) Walter Reed Biosystematic Unit: Mosquito Genera, archived from the original on March 4, 2011 ; Retrieved July 30, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Culex at Fauna Europaea. Retrieved July 22, 2010 .
literature
- John N. Belkin: The Mosquitoes of the South Pacific (Diptera, Culicidae). University of California Press, Berkeley 1962.
- Thomas Löscher, Gerd-Dieter Burchard (eds.), Werner Lang: Tropical medicine in clinic and practice. 4th edition. Thieme, Stuttgart 2010, ISBN 978-3-13-785804-1 .
Web links
- Thomas V. Gaffigan et al. a .: Genus: Culex. In: Systematic Catalog of Culicidae. Walter Reed Biosystematics Unit, accessed on July 22, 2010 (English, list of Culex species in the systematic catalog of mosquitoes of the world).
- Culex Online Key. In: Electronic Keys and Reference Collections. Eutaxa, accessed on July 22, 2010 (English, digital identification key for European Culex larvae).