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TIGER MOSQUITOES
Tiger mosquitoes are several closely related species from
the same genus:
•
The Asian tiger mosquito, Aedes albopictus (Stegomyia albopicta)
•
The Yellow fever mosquito, also dengue mosquito or Egyptian tiger
mosquito, Aedes aegypti (Stegymyia aegypti)
•
The Polynesian tiger mosquito, Aedes polynesiensis (Stegomyia
polynesiensis).
Tiger mosquitoes are widespread throughout the tropical and subtropical
regions of the world, partly also in the Mediterranean area. Tiger mosquitoes
are considered to be the vectors for diseases like chikungunya fever, dengue
fever and Zika.
The Asian Tiger Mosquito
The Asian tiger mosquito (Aedes albopictus) is originally from Southeast Asia. In
the last 30 years it has invaded many countries around the world, including
various regions in the Americas and the Mediterranean. In North America they
adapted to the colder climate so that they now can be found as far north as the
Great Lakes region. A primary reason for the wide distribution is that the Asian
tiger mosquito moves easily in shipments of plants and used tires across the
world.
A detailed distribution of Aedes albopictus in Europe (as of July 2015) developed
by ECDC/VBORNET (European Centre for Desease Prevention and Control) is
shown below.
Behaviour
Unlike most other mosquitoes, this species is a day biter and unusually
aggressive. This is why it has become a major pest in many communities.
Female tiger mosquitoes normally lay their eggs in natural or artificial containers
filled with water. Flower pots, vases, buckets, water barrels, discarded tires, rain
gutters, or even discarded cups with water in them are used as breeding sites.
Their eggs are tolerant to periods of drought, making the Asian tiger mosquito is
perfectly adapted to the urban environment.
What diseases do the Asian tiger mosquitoes transmit?
Asian tiger mosquitoes are considered to be an important transmitting
organism, or vector, of a disease called Link to external sitechikungunya fever.
They can also transmit the disease Link to external sitedengue fever and Zika
fever . The Asian tiger mosquito bites humans, as well as, birds and other
animals. This is why scientists consider it a potential bridge vector, meaning that
it may pick up disease agents from animals and transmit them to humans.
Aedes albopictus (Asian Tiger mosquito / Asiatische Tigermücke) Grafic from I.
Schleip, Biogents AG
Characteristics
The dark-colored Asian tiger mosquito is about 3-10 mm length. A single silvery-
white line that begins on the head and continues down the dorsal side of the
thorax is the surest characteristic marking to identify the Asian tiger mosquito. A
further striking feature is the white markings on the legs.
The life cycle of tiger mosquitoes
The life cycle of the Asian tiger mosquito and the Yellow fever mosquito are very
similar. The eggs are resistant to heat and dryness and are deposited in natural
and artificial containers subject to flooding. When eggs are covered by water, the
larvae hatch. They hang at the surface of the water and breathe through a
snorkel-like siphon at the tip of the abdomen. There are four larval stages that
feed on organic material that they filter out of the water with their mouthparts.
The fourth-stage larva changes into a pupa, that hangs at the surface of the
water and breathes air through two snorkel-like siphons at the front end. The
pupa is a non-feeding stage where the mosquito changes from the larval form
into an adult insect, or imago. The adult mosquito emerges from the pupa and
normally feed on sweet plant juices and nectar to meet their energy
requirement. Only female mosquitoes feed on blood, which they need to
produce their eggs.
The Yellow Fever Mosquito
The yellow fever mosquito, or Egyptian tiger mosquito, is widespread
throughout the tropical and subtropical regions of the world. The species was
once abundant in southern Europe, but disappeared after the 1950's. There are
two main reasons: Firstly, the development of a communal water supply and
better sanitation diminished the number of breeding sites. Secondly, the
intensive use of the insecticide DDT against malaria mosquitoes also killed off
Aedes aegypti mosquitoes.
Today, there are only occasional reports of Aedes aegypti in Europe.
A detailed distribution of Aedes aegypti in Europe (as of July 2015) developed by
ECDC/VBORNET (European Centre for Desease Prevention and Control) is
shown below.
Behaviour
The yellow fever mosquito breeds in close proximity to humans in habitats to
those used by the Asian tiger mosquito. These include: water-filled flower pots,
vases, buckets, water barrels, rain gutters, discarded cups and bottles, plants
that hold small quantities of water, or any other containers. The yellow fever
mosquito is also an aggressive and persistent day biter that prefers to feed on
human beings. Yellow fever mosquitoes regularly enter houses looking for hosts
or places to rest.
What diseases do the Yellow fever mosquitoes transmit?
The yellow fever mosquito is not only the main vector of Link to external
siteyellow fever, but also of Link to external sitedengue fever and Zika fever. It is
also known to transmit a disease called Link to external sitechikungunya.
Characteristics
The dark-colored yellow fever mosquito is about 3-4 mm length. The mosquito
can be identified by a marking in the form of a lyre on the dorsal side of the
thorax and striking white and black patterns on the legs.