Asian tiger mosquito

Aedes albopictus

''Aedes albopictus'' , from the mosquito family, also known as tiger mosquito or forest mosquito, is a mosquito native to the tropical and subtropical areas of Southeast Asia; however, in the past few decades, this species has spread to many countries through the transport of goods and international travel. It is characterized by the white bands on its legs and body.

This mosquito has become a significant pest in many communities because it closely associates with humans , and typically flies and feeds in the daytime in addition to at dusk and dawn. The insect is called a tiger mosquito for its striped appearance, which resembles that of the tiger. ''Ae. albopictus'' is an epidemiologically important vector for the transmission of many viral pathogens, including the yellow fever virus, dengue fever, and Chikungunya fever, as well as several filarial nematodes such as ''Dirofilaria immitis''. ''Aedes albopictus'' is capable of hosting the Zika virus and is considered a potential vector for Zika transmission among humans.
Mosquito - Asian tiger mosquito (Aedes albopictus)  Aedes albopictus,Asian tiger mosquito,Geotagged,Indonesia,Summer

Appearance

The Asian tiger mosquito is about 2 to 10 mm length with a striking white and black pattern. The variation of the body size in adult mosquitoes depends on the density of the larval population and food supply within the breeding water. Since these circumstances are seldom optimal, the average body size of adult mosquitoes is considerably smaller than 10 mm. For example, the average length of the abdomen was calculated to be 2.63 mm, the wings 2.7 mm, and the proboscis 1.88 mm.

The males are roughly 20% smaller than the females, but they are morphologically very similar. However, as in all mosquito species, the antennae of the males in comparison to the females are noticeably bushier and contain auditory receptors to detect the characteristic whine of the female. The maxillary palps of the males are also longer than their proboscis, whereas the females’ maxillary palps are much shorter. In addition, the tarsus of the hind legs of the males is more silvery. Tarsomere IV is roughly 75% silver in the males whereas the females’ is only about 60% silver.

The other characteristics do not differentiate between sexes. A single silvery-white line of tight scales begins between the eyes and continues down the dorsal side of the thorax. This characteristic marking is the easiest and surest way to identify the Asian tiger mosquito.

The proboscis is dark colored, the upper surface of the end segment of the palps is covered in silvery scales, and the labium does not feature a light line on its underside. The compound eyes are distinctly separated from one another. The scute, the dorsal portion of an insect’s thoracic segment, is black alongside the characteristic white midline. On the side of the thorax, the scutellum, and the abdomen are numerous spots covered in white-silvery scales.

Such white-silvery scales can also be found on the tarsus, particularly on the hind legs that are commonly suspended in the air. The bases of tarsomeres I through IV have a ring of white scales, creating the appearance of white and black rings. On the fore legs and middle legs, only the first three tarsomeres have the ring of white scales, whereas tarsomere V on the hind legs is completely white. The femur of each leg is also black with white scales on the end of the “knee”. The femora of the middle legs do not feature a silver line on the base of the upper side, whereas, the femora on the hind legs have short white lines on base of the upper side. The tibiae are black on the base and have no white scales.

The terga on segments II through VI of the abdomen are dark and have an almost triangular silvery-white marking on the base that is not aligned with the silvery bands of scales on the ventral side of the abdomen. The triangular marking and the silvery band are only aligned on abdominal segment VII. The transparent wings have white spots on the base of the costae. With older mosquito specimens, the scales could be partially worn off, making these characteristics not stand out as much.

The typical ''Ae. albopictus'' individual has a length around 2 to 10 mm. As with other members of the mosquito family, the female is equipped with an elongated proboscis that she uses to collect blood to feed her eggs. The Asian tiger mosquito has a rapid bite that allows it to escape most attempts by people to swat it. By contrast, the male member of the species primarily feeds on nectar.

The female lays her eggs near water, not directly into it as other mosquitoes do, but typically near a stagnant pool. However, any open container containing water will suffice for larvae development, even with less than an ounce of water. It can also breed in running water, so stagnant pools of water are not its only breeding sites. It is more likely to lay eggs in water sources near flowers than in water sources without flowers. It has a short flight range , so breeding sites are likely to be close to where this mosquito is found.

Identifying tiger mosquitoes can seem easy with the above description, but many people mistakenly identify it. The best way to be sure is to compare the specimen with several approved pictures of the tiger mosquito.
Aedes_albopictus  Aedes albopictus,Asian tiger mosquito,Fall,Geotagged,Greece

Naming

In 1894, a British-Australian entomologist, Frederick A. Askew Skuse, was the first to scientifically describe the Asian tiger mosquito, which he named ''Culex albopictus'' . Later, the species was assigned to the genus ''Aedes'' and referred to as ''Aedes albopictus''. Like the yellow fever mosquito, it belongs to the subgenus ''Stegomyia'' within the genus ''Aedes''. In 2004, scientists explored higher-level relationships and proposed a new classification within the genus ''Aedes'' and ''Stegomyia'' was elevated to the genus level, making ''Aedes albopictus'' now ''Stegomyia albopicta''. This is, however, a controversial matter, and the use of ''Stegomyia albopicta'' versus ''Aedes albopictus'' is continually debated.Some mosquitoes in North America, such as ''Ochlerotatus canadensis'', have a similar leg pattern.

In Europe, the mosquito ''Culiseta annulata'', which is very common, but does not occur in high densities, can be mistaken for an Asian tiger mosquito because of its black-and-white-ringed legs. However, this species is missing the distinctive white line that runs from the middle of its head and down the thorax. It is also considerably larger than ''Ae. albopictus'', is not black and white, but rather beige and grey striped, and has wings with noticeable veins and four dark, indistinct spots.

In the eastern Mediterranean area, ''Ae. albopictus'' species can be mistaken for ''Aedes cretinus'', which also belongs to the subgenus ''Stegomyia'' and uses similar breeding waters. ''Aedes cretinus'' also has a white stripe on the scute, but it ends shortly before the abdomen, and also has two additional stripes to the left and right of the middle stripe. So far ''Aedes cretinus'' is only located in Cyprus, Greece, Macedonia, Georgia and Turkey.

In Asia, the Asian tiger mosquito can be mistaken for other members of the subgenus ''Stegomyia'', particularly the yellow fever mosquito ''Aedes aegypti'' , because both species display a similar black and white pattern. It can be hard to distinguish ''Ae. albopictus'' from the closely related ''Aedes scutellaris'' , ''Aedes pseudoalbopictus'' and ''Aedes seatoi'' .Since the mid 1960s, the tiger mosquito has spread to Europe, the Americas, the Caribbean, Africa, and the Middle East. As of 2008 ''Ae. albopictus'' was one of the 100 world's worst invasive species according to the Global Invasive Species Database.

As of 2006, ''Ae. albopictus'' was not native to Australia and New Zealand. The species was introduced there multiple times, but has yet to establish itself. This is due to the well-organized entomological surveillance programs in the harbors and airports of these countries. Nevertheless, as of 2006 it has become domestic on the islands in the Torres Strait between Queensland, Australia, and New Guinea.

In Europe, Asian tiger mosquitos first emerged in Albania in 1979, introduced through a shipment of goods from China. In 1990–1991, they were most likely brought to Italy in used tires from Georgia , and since then have spread throughout the entire mainland of Italy, as well as parts of Sicily and Sardinia. Since 1999, they have established themselves on the mainland of France, primarily southern France. In 2002, they were also discovered in a vacation town on the island of Corsica, but did not completely establish themselves there until 2005. In Belgium, they were detected in 2000 and 2013, in 2001 in Montenegro, 2003 in Canton Ticino in southern Switzerland, and Greece, 2004 in Spain and Croatia, 2005 in the Netherlands and Slovenia, and 2006 in Bosnia and Herzegovina. In the fall of 2007, the first tiger mosquito eggs were discovered in Rastatt . Shortly before, they were found in the northern Alps of Switzerland in Canton Aargau. since 2010, it has also been sighted increasingly in Malta during summer. In September 2016, Public Health England found eggs, though no mosquitos, in a lorry park at Folkestone service station on the M20, near Westenhanger, which is 6 miles West of the Eurotunnel.

In the United States, it was initially found in 1983 in Memphis, Tennessee. then at the Port of Houston in a 1985 shipment of used tires, and spread across the South up the East Coast to become prevalent in the Northeast. It was not discovered in Southern California until 2001, then eradicated for over a decade; however, by 2011, it was again being found in Los Angeles County traps, then over the next two years expanded its range to Kern County and San Diego County.

As of 2013, North American land favoring the environmental conditions of the Asian tiger mosquito was expected to more than triple in size in the coming 20 years, especially in urban areas. As of 2017 ''Aedes albopictus'' mosquitoes have been identified in 1,368 counties in 40 U.S states.

In Latin America, the Asian tiger mosquito was first discovered 1986 in Brazil and in 1988 in Argentina and Mexico, as well. Other parts of Latin America where the Asian tiger mosquito was discovered are the Dominican Republic in 1993, Bolivia, Cuba, Honduras, and Guatemala in 1995, El Salvador in 1996, Paraguay in 1999, Panama in 2002, and Uruguay and Nicaragua in 2003.

In Africa, the species was first detected in 1990 in South Africa. In Nigeria, it has been domestic since at least 1991. It spread to Cameroon in 1999/2000, to the Bioko Island of Equatorial Guinea in 2001, and to Gabon in 2006.

In the Middle East, the species was detected in Lebanon in 2003 and in Syria in 2005; the first record in Israel was published in 2003.''Ae. albopictus'' can outcompete and even eradicate other species with similar breeding habitats from the very start of its dispersal to other regions and biotopes. In Kolkata, for example, it was observed in the 1960s that egg depositing containers were being settled by the Asian tiger mosquito in city districts where the malaria mosquito and yellow fever mosquito had both been eliminated by the application of DDT. This may be because primarily the inner walls of the houses were treated with DDT to kill the mosquitoes resting there and fight the malaria mosquito. The yellow fever mosquito also lingers particularly in the inside of buildings and would have been also affected. The Asian tiger mosquito rests in the vicinity of human dwellings would therefore have an advantage over the other two species. In other cases, where the yellow fever mosquito was repressed by the Asian tiger mosquito, for instance in Florida, this explanation does not fit. Other hypotheses include competition in the larval breeding waters, differences in metabolism and reproductive biology, or a major susceptibility to sporozoans .

Another species, which was suppressed by the migrating ''Ae. albopictus'' was ''Ae. guamensis'' in Guam.

The Asian tiger mosquito is similar, in terms of its close socialization with humans, to the common house mosquito . Among other differences in their biology, ''Culex pipiens'' prefers larger breeding waters and is more tolerant to cold. In this respect, no significant competition or suppression between the two species likely occurs.

A possible competition among mosquito species that all lay their eggs in knotholes and other similar places has yet to be observed.

In Europe, the Asian tiger mosquito apparently covers an extensive new niche. This means that no native, long-established species conflict with the dispersal of ''Ae. albopictus''.

Food

Like other mosquito species, only the females require a blood meal to develop their eggs. Apart from that, they feed on nectar and other sweet plant juices just as the males do. In regards to host location, carbon dioxide and organic substances produced from the host, humidity, and optical recognition play important roles.

The search for a host takes place in two phases. First, the mosquito exhibits a nonspecific searching behavior until it perceives host stimulants, whereupon it secondly takes a targeted approach. For catching tiger mosquitoes with special traps, carbon dioxide and a combination of chemicals that naturally occur in human skin are the most attractive.

The Asian tiger mosquito particularly bites in forests during the day, so has been known as the forest day mosquito. Depending upon region and biotype, activity peaks differ, but for the most part, they rest during the morning and night hours. They search for their hosts inside and outside of human dwellings, but are particularly active outside. The size of the blood meal depends upon the size of the mosquito, but it is usually around 2 μl. Their bites are not necessarily painful, but they are more noticeable than those from other kinds of mosquitoes. Tiger mosquitoes generally tend to bite a human host more than once if they are able to.

''Ae. albopictus'' also bites other mammals besides humans, as well as birds. The females are always on the search for a host and are persistent but cautious when it comes to their blood meal and host location. Their blood meal is often broken off before enough blood has been ingested for the development of their eggs, so Asian tiger mosquitoes bite multiple hosts during their development cycle of the egg, making them particularly efficient at transmitting diseases. The mannerism of biting diverse host species enables the Asian tiger mosquito to be a potential bridge vector for certain pathogens that can jump species boundaries, for example the West Nile virus.

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Taxonomy
KingdomAnimalia
DivisionArthropoda
ClassInsecta
OrderDiptera
FamilyCulicidae
GenusAedes
SpeciesA. albopictus
Photographed in
Greece
Indonesia