Aedes albopictus

Geographic Range

As explained by their colloquial name, Asian tiger mosquitos ( Aedes albopictus ) are native to Eastern Asia, stretching into India, Japan, and several islands in the Pacific (Australasia). Due to A. albopictus excellent ability to colonize new environments, it has been introduced to a variety of other places in the world. Over the past thirty years the species has spread to Italy and other regions in the Mediterranean basin, as well as parts of Africa, Madagascar, Brazil, Central America, the Caribbean, and most of the United States (specifically the East coast and the Midwest).

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
• palearctic palearctic
  • native native
• oriental oriental
  • native native
• ethiopian ethiopian
  • introduced introduced
• neotropical neotropical
  • introduced introduced
• oceanic islands oceanic islands
  • introduced introduced

Habitat

Aedes albopictus chooses a habitat based on availability of food resources and availability of locations for reproduction and development. The species is capable of utilizing natural as well as artificial container habitats. It is perhaps most well known for utilizing tires, but it has since adapted the ability to develop in a range of natural and artificial areas including bird baths, clogged gutters, and litter.

Because members of this species are weak fliers, they remain within the same habitat their entire lives. Besides having a proper breeding and reproduction habitat, proper food resources must be available as well. This mosquito has developed very weak host specificity, and thus does not have trouble finding food in most environments.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial
• freshwater freshwater

Physical Description

Aedes albopictus received its common name because of its distinguishable pattern of white and black stripes along it's palpus and tarsi. Beyond that, they are similar to most others in the Culicidae family (except for their pointed abdomens). Males are slightly smaller than females in the species, but they are very similar morphologically. The exception to this lies in the antennae (resting at the top of the mosquito, just above the mouthparts) which are much bushier in the males, and the maxillary palps which are longer in males than their proboscis (which isn’t needed for sucking). In females the palps are much smaller than their proboscis, which is crucial for taking blood meals. Aedes albopictus has a black proboscis, eyes, and labium all at the anterior end of the insect, while the black scutum contains a white line dissecting the dorsal part of the mosquito in half. Tergites behind the scutum are dark with bright white markings on them. Most legs are alternating in color, but some are solely black.

Eggs of Aedes albopictus are shaped much like cigars. They are blunt at the anterior end and taper at the posterior end. Each egg is spotted with large, smoothly rounded outer tubercles, with small cell fields scattered around the rest of the egg. The eggs eventually hatch into larva, which are sometimes called wigglers, which are very small and must be studied under a microscope. They are active feeders, and thus are equipped with mouth parts. They also have long, protruding breathing siphons used for oxygen acquisition. Larva are lighter in color when compared to most other mosquito species. They are very similar to Aedes aegypti , which is a closely related species. There are a few small differences that help to distinguish the two species, located on the mesothorax and metathorax. For example, Aedes albopictus has long pleural hair groups lacking a long spine that can be found on the other species. Pupae are also aquatic. They retain the breathing siphon, but appear as a dark ball at the other end.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• ornamentation ornamentation

Development

Eggs of Aedes albopictus are laid along the side of artificial or man-made containers and will hatch when water levels rise above the location of the egg, submerging it. The eggs will hatch in water with low turbidity and a pH ranging from 5.2 to 7.6 (optimal range from 6.8 to 7.6). The ideal pool of water has a high organic nitrogen content for feeding upon. Larval size and duration of larval development are influenced by a variety of factors: temperature, food supply, crowding, and sex. Larval development includes four instars and can be as short as four days, or as long as 42 in a situation where the larva lacks adequate food, in which case it will die.

Larvae will eventually close themselves in pupaes, a process which under ideal conditions will last two days. This number can vary for males and females, though. The average number of hours for males is 32 to 36, while for females it is between 49 and 52. At this point an adult will emerge from the pupa, where it will soon look to mate. The adults have reached sexual maturity once they have left the pupa, and begin feeding and mating within two or three days.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

Females can mate up to four times in a lifetime, depending on length of lifespan. Males typically have slightly shorter lifespans, but have fewer restrictions on mating. They can both mate multiple times with multiple individuals. Males will form leks, or swarms, a few feet off the ground, which will attract females. Males will secrete stimulants which provide one stimulus for ovarian development (blood meal provides the other stimulus). Mating will occur in flight and last for 5 to 15 seconds. At the end of the female’s gonotrophic cycle she oviposits her eggs, placing them at a few various locations.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Once females emerge from pupae, they take in a blood meal within the first two the three days, which is vital for the development of eggs. There is no one mating season for Aedes albopictus , but the species is likely to mate during the rainy season which varies geographically. This assures the quickest development time for the eggs, which begin hatching once submerged in a stagnant pool of water. Females may lay from 45 to 200 eggs per year.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

There is no parental investment once the female has laid her eggs in a suitable location.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Almost all studies on lifespan of Aedes albopictus have focused on the life of the female, so not much is known about the longevity of the male. It seems that environmental factors have a large effect on how long an individual can live. In a temperate climate with relatively high humidity, the average lifespan was between 30 and 40 days. In the laboratory, various experiments with different foods in different amounts could allow females to live up to 117 days. This was an extreme situation which is not possible in the natural environment.

Behavior

Aedes albopictus does not have much variation in its behavior; mostly just feeding and mating. From the second they leave their pupa, they begin the search for a host to feed on. They do their searching at two different periods of the day: one period early in the morning, and another later on in the evening. Depending on the environment, mosquitoes have adapted to adjust their hours of maximal feeding so that it is most probable they find a host.

Once they feed, they begin to search for a mate. Aedes albopictus is a weak flier, so almost all its activities remain within a range of 500 meters. Most individuals don't even make it that far. When not feeding or mating, individuals have been observed resting in open clearings or areas where there is ample space and containers for egg laying. In more temperate areas they have been found resting in forest fringes where a canopy is present.

• Key Behaviors
• flies
• diurnal diurnal
• parasite parasite
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

The home range of Aedes albopictus is an area 457.2 m in diameter, centered where females can oviposit eggs. They are weak fliers that don't have to move too far due to their wide ranging diet.

Communication and Perception

There is very little communication that occurs between individuals of this species. Almost all communication is involved with mating. Antennae contain auditory receptors that allow the males to hear the whine of females which helps to locate them. Once in the same vicinity, males engage in lekking behavior, forming clusters in mid-air which invite females to mate. The males then secrete a substance that helps to officially begin the mating process. Individuals pair off, mate, and don't interact again.

Besides the auditory receptors, all mosquitoes in the species have compound eyes to help locate just about anything they need (mates, food, areas to lay eggs).

• Communication Channels
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• acoustic acoustic

Food Habits

Males of the species are not parasitic. They feed on nectars and sugar-rich plant juices. The females also feed on these juices, but need a blood meal to develop eggs. Asian tiger mosquitoes are efficient in that they can feed on many different species (of both mammals and birds). Aedes albopictus is an opportunistic feeder but prefers mammals above all else. Some of the most common species fed upon are domestic dogs , deer , rabbits and humans . They can feed on squirrels, opossums, bovines, raccoons, turtles, rats, and cats. This host variability allows this species to thrive in a wide range of environments.

When searching for a host, there are two phases. First, a female mosquito exhibits a nonspecific searching behavior until the perception of host stimulants. A mosquito then targets the host and begins an approach. Lastly, this mosquito lands on its host and thrusts its proboscis through the skin to find a vessel to feed from (making females of this species solenophagic).

• Primary Diet
• herbivore herbivore
  • nectarivore nectarivore

• Animal Foods
• blood

• Plant Foods
• nectar

Predation

Many different species from different phylum prey upon Aedes albopictus . The majority of these predators consume mosquitoes in their larval phase. For example, a copepod predator, Mesocyclops leuckarti pilosa has been found to have the ability to take out an entire group of larva in a container. Another copepod, Macrocyclops albidus , which has a wide geographic range (unlike Mesocyclops leuckarti pilosa ) is able to knock out a dense population in tire piles in 8 to 10 weeks. Some flatworms in the phylum Platyhelminthes also prey on larvae. Other mosquitoes including various species in the Toxorynchites genus, have shown an excellent ability to maintain Asian tiger mosquito populations and are being considered as a possible control species.

Bats and birds are the most common predators of adult mosquitoes. In certain areas, spiders are known to catch Aedes albopictus and feed on them.

Ecosystem Roles

A wide range of organisms prey Aedes albopictus as larvae when they are most defenseless. Various families of fungi infect larvae and tests have been done to see if they could be considered as a biological control agent of mosquitoes. Specifically, Coelomonoyces stegomyia and Tolypocladium cylindrosporum fungi cause damage to larval populations. Protozoan parasites can also cause damage, specifically to the midgut of larvae. Ascogregarina taiwanensis is one protozoan example, as well as other members from the genus Ascogregarina . Nematodes have been found parasitizing Asian tiger mosquitoes, but only in laboratory tests. Romanomermis culicivorax which has a history of burrowing into the cuticle of larval mosquitoes was introduced in experiments, but has not been found in nature parasitizing on Aedes albopictus . Other pathogens in bacterium and ciliate families have also been found to cause damage.

Aedes albopictus plays a large role in the spread of disease, as females have the potential to spread blood-borne diseases. This is of particular concern with zoonotic diseases as mosquitoes feed on many species of mammals and birds as well as humans.

• Ecosystem Impact
• parasite parasite

Economic Importance for Humans: Positive

Asian tiger mosquitoes provide no benefits to humans.

Economic Importance for Humans: Negative

Aedes albopictus acts as a parasite and a vector to a large variety of other species. Mosquitoes have a wide range of species they can feed upon. After being bitten by a mosquito, a host will become irritated in that spot due to a typical immune response against mosquito saliva. When feeding on a host, the species can pass on one of many different arboviruses, along with protzoans and filarial nematodes. Aedes albopictus is a known vector of dengue fever, yellow fever, West Nile virus, Eastern equine encephalitis, and Venezuelan equine encephalitis among many more. Mosquitoes are known to have caused outbreaks of Chikungunya Fever in both France and Italy. It is also notorious for vectoring parasitic roundworms Dirofilaria immitis , which cause heartworm in domestic dogs and cats. Because of the large number of pathogens Aedes albopictus carries and its ability to inhabit much of the world throughout the year, mosquitoes spread significant amounts of disease.

• Negative Impacts
• injures humans
  • bites or stings
  • carries human disease
• causes or carries domestic animal disease causes or carries domestic animal disease

Conservation Status

Aedes albopictus is a notorious vector of various harmful pathogens to a number of species. All focus placed on the species concerns controlling it rather than conserving it.

Additional Links

Encyclopedia of Life

Contributors

Kyle Hartman (author), University of Michigan-Ann Arbor, Heidi Liere (editor), University of Michigan-Ann Arbor, John Marino (editor), University of Michigan-Ann Arbor, Barry OConnor (editor), University of Michigan-Ann Arbor, Rachelle Sterling (editor), Special Projects.

References

Braunbeck, T., N. Becker. 2008. First record of Stegomyia albopicta in Germany. Journal of the European Mosquito Control Association . Accessed February 10, 2010 at http://e-m-b.org/sites/e-m-b.org/files/European_Mosquito_Bulletin_Publications811/EMB26/EMB26_1.pdf .

Carrieri, M., G. Celli. 2000. Population structure of Aedes albopictus: the mosquito which is colonizing Mediterranean countries. Heredity , Vol. 84: 331–337. Accessed March 15, 2010 at http://www.discoverlife.org/mp/20q?go=http://www.nature.com/cgi-taf/DynaPage.taf%3Ffile%3D/hdy/journal/v84/n3/full/6886760a.html#bib27 .

Eritja, R., E. Merdic, D. Petrić. 2009. "Development of Aedes albopictus Risk Maps" (On-line pdf). European Centre for Disease Prevention and Control. Accessed March 10, 2010 at http://www.ecdc.europa.eu/en/publications/Publications/0905_TER_Development_of_Aedes_Albopictus_Risk_Maps.pdf .

Hitoshi, K., T. Nguyen, T. Masahiro. 2010. Geographic Distribution of Aedes aegypti and Aedes albopictus Collected from Used Tires in Vietnam. Journal of the American Mosquito Control Association , Volume 26 Issue 1: 1-9. Accessed March 25, 2010 at http://www.bioone.org.proxy.lib.umich.edu/doi/full/10.2987/09-5945.1 .

Rai, K. 1999. Four Decades of Vector Biology . Notre Dame, IN: University of Notre Dame Press.

1995. Biology, Disease Relationships, and Control of Aedes albopictus . Washington D.C.: Pan American Health Orginization.

1997. Aedes albopictus in the United States: Ten-Year Presence and Public Health Implications. Emerging Infectious Diseases , Volume 3, Issue 3: 329–334. Accessed March 15, 2010 at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627635/pdf/9284377.pdf .

2010. "Aedes albopictus" (On-line). Rutgers Entomology. Accessed March 10, 2010 at http://www.rci.rutgers.edu/~insects/albo.htm .

2012. Are Aedes albopictus or other mosquito species from northern Italy competent to sustain new arboviral outbreaks?. Medical and Veterinary Entomology , Volume 24, Issue 1: 83-87. Accessed March 15, 2010 at http://www3.interscience.wiley.com/cgi-bin/fulltext/123282824/HTMLSTART .

University of Florida. 2008. "Asian Tiger Mosquito" (On-line). Featured Creatures. Accessed March 22, 2010 at http://entnemdept.ufl.edu/creatures/aquatic/asian_tiger.htm .

2005. "Information on Aedes albopictus " (On-line). CDC Division of Vector-Borne Infectious Diseases. Accessed March 10, 2010 at http://www.cdc.gov/ncidod/dvbid/Arbor/albopic_new.htm .