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Aedes albopictus (also classified as Stegomyia albopicta in some taxonomic treatments), commonly called the Asian tiger mosquito or the forest day mosquito, is a day-biting, container-breeding mosquito in the family Culicidae (subfamily Culicinae, tribe Aedini, genus Aedes, subgenus Stegomyia). It is native to tropical and subtropical Southeast Asia and to temperate parts of East Asia. Over the last five decades it has spread through human trade to every inhabited continent, and it is now established in parts of Europe, the Americas, Africa, and the Pacific. It is listed among the "100 of the world's worst invasive alien species" by the Invasive Species Specialist Group of the International Union for Conservation of Nature.

In medical entomology, Aedes albopictus is a major vector of chikungunya virus, and it is a competent vector of dengue virus and Zika virus. It has been found infected with, or has been shown in the laboratory to transmit, more than 20 arboviruses and some filarial nematodes, but competence in the laboratory does not imply an important role in nature. It feeds on a broader range of hosts than Aedes aegypti, and it can therefore act as a bridge vector for zoonotic viruses, although it is most important as a vector of viruses that circulate between humans.

Two traits shape its response to climate change. First, temperate populations produce diapausing eggs in response to short day lengths, and these eggs survive winter, so the species can persist in regions that are too cold for Aedes aegypti. Second, models of transmission suggest that its optimum temperature is lower than that of Aedes aegypti, so that transmission by Aedes albopictus is possible at cooler temperatures. Together with the movement of infected travelers, these traits explain why this species is the main vector in the local outbreaks of dengue and chikungunya in temperate Europe.

Systematics

Aedes albopictus was described by Frederick Askew Skuse in 1894 as Culex albopictus, from specimens collected in Calcutta (now Kolkata), India. It belongs to the Scutellaris group of the subgenus Stegomyia. Unlike Aedes aegypti, which has a wild form (Ae. aegypti formosus) and a human-associated form (Ae. aegypti aegypti), Aedes albopictus is not divided into recognized subspecies, and it breeds in natural containers and in artificial ones. Natural larval sites are tree holes, bamboo stumps, leaf axils of plants such as bromeliads, and rock pools. Artificial sites are tires, flower vases, buckets, and the catch basins of storm drains.

Morphology

Adult Aedes albopictus are small to medium mosquitoes, usually about 2 to 10 mm long, with a black body and white scales. The common name refers to the striped legs and body. Identification of adult females is based on the following characters, which are best checked on undamaged specimens, because scales are lost in traps and with age:

Several other Aedes species with white-striped bodies occur in the same regions, so surveillance programs confirm identification with a microscope or with molecular methods.

Native range

The native range of Aedes albopictus is Southeast Asia, and it includes the islands of the western Pacific and Indian Ocean and parts of East Asia, including temperate China, Korea, and Japan. In its native forests, the species lives at the edge of the forest and breeds in plant containers.

Spread

The global spread of Aedes albopictus is a result of the movement of eggs and larvae in containers. Eggs can survive drying, so they are carried in the water that remains in used tires, in plants such as "lucky bamboo" (Dracaena sanderiana), and in other goods. Adults can also be carried in vehicles. Documented events include:

• Indian Ocean and Pacific. The species reached islands in the western Indian Ocean (Madagascar, Réunion, Mauritius, and the Seychelles) in the nineteenth century or earlier and arrived in Hawaii in the late nineteenth century.
• North America. The first permanent population in the continental United States was found in Houston, Texas, in 1985, and it was linked to the import of used tires from Japan. It has since been found in more than 30 states, and it is established as far north as the southern parts of New England and the midwestern states. A separate introduction in California in 2001 was linked to lucky bamboo from southern China.
• South America and the Caribbean. It was recorded in Brazil in 1986 and has since spread through most countries in the region.
• Europe. It was first recorded in Albania in 1979. In Italy, it was found in Genoa in 1990 and in the Padua area in 1991, in association with used tires imported from the United States. It then spread through the Mediterranean region and, with the help of road traffic, into inland regions. It is now established in more than a dozen European countries, including France, Spain, Croatia, Greece, Switzerland, and Germany, and it is detected repeatedly farther north.
• Africa. It was recorded in Nigeria in 1991, then in Cameroon and in other countries of western and central Africa, where it has become common in some cities and plantations.

Studies of population genetics show that there were several independent introductions from different parts of Asia. Introduced populations have mixed ancestry in many places, and they contain populations that act as sources of further spread. The success of the species is related to its tolerance of a range of containers, the resistance of its eggs, its photoperiodic diapause in temperate populations, and its ability to feed on many hosts.

The genome of Aedes albopictus is large for a mosquito. Assemblies are about 1.5 to 2 gigabases, which is larger than that of Aedes aegypti (about 1.3 Gb) and much larger than that of Anopheles gambiae (about 0.27 Gb). Repetitive sequences, in particular transposable elements, make up about two thirds of the genome. Other features that have been described include:

• Expansions of gene families for chemosensory receptors, detoxification enzymes (cytochrome P450 enzymes, glutathione S-transferases, and carboxylesterases), and regulators of diapause, which may contribute to the use of many hosts and habitats and to the evolution of insecticide resistance.
• Many integrated sequences derived from RNA viruses (non-retroviral endogenous viral elements). They often occur in clusters that produce PIWI-interacting RNAs (piRNAs), and it has been proposed that they take part in the antiviral defense of the mosquito, but their function is still being studied.

Life cycle

The life cycle of Aedes albopictus has four stages: egg, four larval instars, pupa, and adult. The time needed for development depends on temperature and on food. At about 28 to 30 °C, development from egg to adult takes about 7 to 10 days, and at 18 °C it takes about three weeks or longer. Larvae grow well in small containers that have organic matter, and they feed on microorganisms and detritus.

A female lays eggs a few at a time on the wet walls of containers just above the water line. She often distributes a batch among several containers, which is called skip oviposition. The black eggs are about 0.5 mm long. They complete embryonic development within a few days, but they do not hatch until they are submerged. They can survive drying for several months, so that populations persist through dry periods and can be transported over long distances. Hatching occurs when water covers the eggs and the oxygen level falls.

Photoperiodic diapause

In temperate populations of Aedes albopictus, females that experience short day lengths and cooler temperatures during development lay diapausing eggs. This maternal effect is a response to photoperiod and not to cold in the egg. Diapausing eggs have larger lipid reserves, are more resistant to drying, and do not hatch under conditions that would stimulate hatching in non-diapausing eggs, until the diapause is terminated by exposure to winter conditions or to longer days. This prevents hatching and the death of larvae in autumn and winter.

The critical photoperiod that triggers diapause varies with latitude, and populations from higher latitudes enter diapause at longer day lengths. Populations in the United States evolved a latitudinal gradient in the response within a few decades of the introduction. Tropical populations, such as those in Brazil, may have little or no diapause. Eggs in diapause can tolerate temperatures below freezing for limited periods, but survival in the field depends on how well sheltered the sites are. Populations are established mostly in areas where the average winter temperature does not fall far below 0 °C, and the exact limit is a subject of research.

Adult behavior and dispersal

Female Aedes albopictus feed mostly during the day, with peaks of activity in the morning and in the late afternoon. They locate hosts with carbon dioxide, odors from skin, and visual cues. Adults rest in shaded vegetation outdoors, and they enter houses less than Aedes aegypti does, but they do enter, particularly in cities without screens.

Active flight dispersal is short. Most females stay within about 100 to 200 m of the place where they emerged, so local outbreaks form clusters. Long-distance movement is mostly passive, by vehicles and trade.

Host use

Aedes albopictus is an opportunistic feeder. The proportion of blood meals taken from humans (the human blood index, Q_h) is high in many urban and suburban settings, and it is lower in rural and forest-edge habitats, where mammals, birds, and reptiles are also bitten. This has two effects on transmission. A lower human blood index reduces the transmission of viruses that need humans as the host in both directions, such as dengue. In the Ross-Macdonald model, the vectorial capacity is proportional to Q_h² (see below). For example, a change in Q_h from 0.9 to 0.4 reduces the vectorial capacity by a factor of (0.9/0.4)² ≈ 5. In contrast, feeding on animals allows the mosquito to acquire zoonotic viruses and to carry them to humans.

Competition with other species

In the southeastern United States, the arrival of Aedes albopictus in the 1980s and 1990s was followed by a decline of Aedes aegypti in many areas, which then persisted mostly in urban cores and in the hottest regions, such as southern Florida. A similar replacement was seen in Bermuda. Two processes have been proposed. In larval competition, Ae. albopictus can do better in containers with low-quality food, such as leaf litter. In reproductive interference, which is called satyrization, males of Ae. albopictus mate with females of Ae. aegypti, and the females then become less likely to mate again and do not produce viable offspring. The reverse cross occurs much less often. The importance of each process differs among sites, and Ae. aegypti resists drying and heat better, which allows it to persist in hot urban areas. Aedes albopictus also competes with native container-breeding mosquitoes, such as Aedes triseriatus and Aedes japonicus in North America, and its effects on them are variable.

Barriers in the mosquito

After a female Aedes albopictus feeds on a viremic host, a virus must infect the midgut, replicate, escape from the midgut into the hemolymph, infect other tissues, and infect the salivary glands, before it can be released in saliva. At each step, the mosquito has barriers (the midgut infection and escape barriers, and the salivary gland infection and escape barriers). The ability to transmit a virus is called vector competence. It differs among virus strains and among mosquito populations, and it depends on temperature. Antiviral defense includes the RNA interference pathway (with Dicer-2 and Argonaute-2), a PIWI-interacting RNA pathway, and the Toll, IMD, and JAK-STAT immune pathways. A single mosquito is infected for life, usually without obvious disease.

Pathogens

Transmission models

For a vector-borne pathogen transmitted by Aedes albopictus, the temperature-dependent basic reproduction number R₀ can be written in the form used in trait-based models:

where a is the biting rate, b and c are the probabilities of transmission from mosquito to human and from human to mosquito, μ is the daily mortality of the adult mosquito, PDR is the pathogen development rate (the inverse of the extrinsic incubation period), EFD is the number of eggs per female per day, p_EA is the survival from egg to adult, MDR is the development rate of the immature stages, N is the density of humans, and r is the rate of recovery of humans. Here a = Q_h f, the product of the human blood index and the rate of feeding cycles. All traits depend on temperature. Many are described by the asymmetric Brière function:

The survival of mosquitoes through the extrinsic incubation period is e^−_μn_, which depends strongly on temperature. For example, if μ = 0.1 per day, a mosquito survives a 14-day period with probability e^−1.4 ≈ 0.25, and a 7-day period with probability e^−0.7 ≈ 0.50, so that warming that shortens the incubation period doubles this term.

Thermal niche

Models of transmission that were fitted to laboratory data estimate that the optimum temperature for dengue and chikungunya transmission by Aedes albopictus is about 26 °C (a lower limit of about 16 °C and an upper limit of about 31 to 32 °C). The values for Aedes aegypti are higher, with an optimum of about 29 °C and an upper limit of about 35 °C. The estimates have wide uncertainty ranges. They imply that:

• In cool-temperate and subtropical regions, and at high elevation, Ae. albopictus can transmit under conditions that are too cool for Ae. aegypti.
• In very hot lowland regions, in the hottest months, Ae. aegypti is expected to be the better vector, and extreme heat can reduce the survival of Ae. albopictus unless it finds shaded and humid refuges.

Eggs and larvae of Ae. albopictus develop at temperatures at which Ae. aegypti does poorly, and adult mosquitoes of Ae. albopictus survive better than Ae. aegypti at some cool temperatures. The effect of temperature on a population in the field also depends on microclimate, rainfall, and the availability of containers.

Range expansion and climate

The geographic range of Aedes albopictus is limited by winter cold, by the lack of water, and by hot dry summers. Warmer winters and longer warm seasons can allow the species to survive and to establish in higher latitudes and elevations, as has been seen in Europe, in North America, and in East Asia, where it has moved north in recent decades. Models that use projections of climate suggest expansion in temperate regions and in highlands by the middle of the century, with large differences depending on the scenario and the model. Other factors also drive the spread, in particular trade and travel, which provide new introductions, and urban conditions that provide containers.

Local transmission in Europe

Dengue and chikungunya do not circulate continuously in Europe. They are introduced by travelers who are infected in other regions, and Ae. albopictus can start local transmission when it bites a viremic traveler during the warm months. Documented events include:

• Chikungunya. Outbreaks in Italy in 2007 (Emilia-Romagna, about 330 estimated cases) and in 2017 (Lazio and Calabria, with several hundred cases), and small clusters in France in 2010, 2014, and 2017, and in the Paris region in 2024. In 2025, France and Italy reported larger numbers of local cases than in any previous year, associated with many imported cases from the outbreak in the Indian Ocean.
• Dengue. Local cases in Europe rose from a few a year before 2022 to dozens or more in later years. France reported 65 local cases in 2022, Europe had about 130 in 2023 (mostly in Italy and France), and in 2024 there were several hundred, including an outbreak of more than 200 cases in Fano in the Marche region of Italy.
• Zika. Three local cases in Hyères, in southern France, in 2019.

The trend is related to the increase in imported cases, the expansion of the vector, and warm summers in which the extrinsic incubation period is short. The relative effects of these factors are difficult to separate. In years with many imported cases, local transmission is more likely even without unusual weather.

Because Aedes albopictus is active in the daytime and does not enter many of the traps that are used for Culex and Anopheles, surveillance uses specialized methods:

• Ovitraps are dark containers with water and an oviposition surface, where females lay eggs. They are cheap and sensitive, and they detect low densities of the mosquito when a new population invades. Species are confirmed by hatching and by identifying larvae or by molecular methods.
• Adult traps, such as the BG-Sentinel trap with a lure that imitates skin odor and with carbon dioxide, collect host-seeking adults. Collected mosquitoes can be tested for viral RNA in pools.
• Larval surveys count breeding sites, and they are used to calculate the house index, the container index, and the Breteau index. These indices correlate only weakly with the risk of disease, and thresholds were developed for Aedes aegypti.
• Citizen science. Smartphone applications such as Mosquito Alert allow people to send photographs of mosquitoes, which are checked by experts, and they have detected new populations in several European countries.

Public health agencies in Europe and North America recommend rapid investigation of imported cases in the mosquito season, with the surveillance of mosquitoes and control of vectors within a radius of a few hundred meters around the home and workplace of the patient. The radius is chosen on the basis of the short flight range of the mosquito.

Resistance to insecticides in Aedes albopictus has increased as a result of spraying against mosquitoes and of agricultural use of pesticides. It was less common than in Aedes aegypti in the past, in part because Ae. albopictus is exposed less to indoor spraying.

Rotation of insecticides with different modes of action, the use of biological larvicides, and the monitoring of resistance with bioassays are the main tools to manage resistance.

Control of Aedes albopictus is difficult. The mosquito breeds in many small and hidden containers, it rests outdoors, where indoor residual spraying does not reach, and it often lives on private property, so the cooperation of residents is needed. Programs use an integrated approach:

• Source reduction and larviciding. Removal or covering of containers (tires, bottles, plant dishes) is the basis of control and depends on community participation. Storm drains and other sites that cannot be removed are treated with biological larvicides, such as Bacillus thuringiensis israelensis (Bti) and Lysinibacillus sphaericus, with spinosad, or with the insect growth regulators methoprene and pyriproxyfen. Resistance to Bti is rare in the field.
• Adulticiding. Targeted spraying on vegetation and walls, and space spraying, are used near cases during outbreaks. The effect is short, and resistance limits some products.
• Autodissemination. Gravid females visit stations that are treated with pyriproxyfen, and they carry the chemical to other containers during skip oviposition. Field trials have shown effects on populations in some settings, and the method is not widely used.
• Personal protection. Repellents, clothing, and screens reduce bites, and the daytime biting makes bed nets less useful.

Wolbachia-based methods

Unlike Aedes aegypti, Aedes albopictus is naturally infected with two strains of the bacterium Wolbachia, _w_AlbA and _w_AlbB. They cause cytoplasmic incompatibility with uninfected mosquitoes, but they do not block virus transmission strongly. Two approaches have been developed:

• Population suppression. Males carrying a different, incompatible Wolbachia infection are released, so that wild females that mate with them produce no viable eggs. A line with a third strain (_w_Pip), together with the two native strains, was used in field trials in Guangzhou, China, in which releases of males, combined with low-dose irradiation that sterilizes females that are released accidentally, reduced the wild population by more than 90 percent. Releases in Italy and other countries have also been tested. This is the combined incompatible insect technique and sterile insect technique (IIT-SIT), which requires continuous releases.
• Population replacement. Mosquitoes with the _w_Mel strain of Wolbachia were shown in the laboratory to induce incompatibility and to block dengue transmission in Ae. albopictus. This approach has not been used in the field on a large scale for this species.

Genetic approaches

Female-specific flightless (fsRIDL) lines of Aedes albopictus have been developed in the laboratory. In this method, a repressible lethal gene causes the female offspring of released males to be unable to fly. Other systems, such as precision-guided sterile insect technique (pgSIT) that uses CRISPR-Cas9, have been demonstrated mainly in Aedes aegypti, and gene drive approaches for Ae. albopictus are at an early stage. Regulation, public acceptance, and ecological assessment are important parts of the introduction of any such method.

How did the chikungunya virus E1-A226V mutation increase transmission by *Aedes albopictus*?

During the 2005–2006 Indian Ocean epidemic, chikungunya virus acquired an alanine-to-valine substitution at position 226 of the E1 envelope glycoprotein (E1-A226V), accompanied by epistatic mutations in the E2 protein. This substitution reduces the cholesterol dependence of viral membrane fusion within endosomes of *Aedes albopictus* midgut epithelial cells, increasing midgut infection efficiency and shortening the extrinsic incubation period by several days.

How does photoperiodic diapause allow *Aedes albopictus* to colonize temperate latitudes?

When pupal and adult female *Aedes albopictus* in temperate populations experience short autumn day lengths below a latitude-specific critical photoperiod, maternal neuroendocrine signaling induces embryonic diapause in their developing eggs. These diapausing pharate first-instar larvae upregulate lipid storage, stress-response heat-shock proteins, and cuticular hydrocarbons, enabling them to survive sub-zero winter temperatures and resist premature hatching until spring warming.

How does *Aedes albopictus* displace *Aedes aegypti* through satyrization?

Where *Aedes albopictus* and *Aedes aegypti* co-occur in vegetated suburban habitats, *Aedes albopictus* larvae outcompete *Aedes aegypti* in detritus-poor containers, while adult male *Aedes albopictus* asymmetrically cross-mate with female *Aedes aegypti* in a process called satyrization. Male accessory gland proteins transferred during this interspecific mating render the *Aedes aegypti* female refractory to subsequent conspecific mating, sterilizing her for life.

• Aedes aegypti
• Chikungunya
• Dengue fever
• Zika fever
• Vector control
• Wolbachia
• Invasive species