The yellow fever mosquito, Aedes aegypti, is a mosquito that can spread the dengue fever,
chikungunya, and yellow fever viruses, and other diseases. The mosquito can be recognized
by white markings on its legs and a marking in the form of a lyre on the thorax. The mosquito
originated in Africa, but is now found in tropical and subtropical regions throughout
the world.
Spread of disease and prevention Aedes aegypti is a vector for transmitting
several tropical fevers. Only the female bites for blood, which she needs to mature her eggs.
To find a host, these mosquitoes are attracted to chemical compounds emitted by mammals.
These compounds include ammonia, carbon dioxide, lactic acid, and octenol. Scientists at the
Agricultural Research Service have studied the specific chemical structure of octenol
to better understand why this chemical attracts the mosquito to its host. They found the mosquito
has a preference for "right-handed" octenol molecules.
The yellow fever mosquito can also contribute to the spread of reticulum cell sarcoma among
Syrian hamsters. The CDC traveler's page on preventing dengue
fever suggests using mosquito repellents that contain DEET. It also suggests:
Although Aedes aegypti mosquitoes most commonly bite at dusk and dawn, indoors, in shady areas,
or when the weather is cloudy, "they can bite and spread infection all year long and at
any time of day." The mosquitoes prefer to breed in areas of
stagnant water, such as flower vases, uncovered barrels, buckets, and discarded tires, but
the most dangerous areas are wet shower floors and toilet tanks, as they allow the mosquitos
to breed in the residence. Research has shown that certain chemicals emanating from bacteria
in water containers stimulate the female mosquitoes to lay their eggs. They are particularly motivated
to lay eggs in water containers that have the correct amounts of specific fatty acids
associated with bacteria involved in the degradation of leaves and other organic matter in water.
The chemicals associated with the microbial stew are far more stimulating to discerning
female mosquitoes than plain or filtered water in which the bacteria once lived.
Wear long-sleeved clothing and long trousers when outdoors during the day and evening
Spray permethrin or DEET repellents on clothing, as mosquitos may bite through thin clothing
Use mosquito netting over the bed if the bedroom is not air conditioned or screened, and for
additional protection, treat the mosquito netting with the insecticide permethrin
Spray permethrin or a similar insecticide in the bedroom before retiring
Mosquito control is currently the best method for disease prevention. This primarily includes
source reduction, pesticide spraying or "fogging", or the use of mosquito traps like the lethal
ovitrap. Although the lifespan of an adult A. aegypti
is two to four weeks depending on conditions, the eggs can be viable for over a year in
a dry state, which allows the mosquito to re-emerge after a cold winter or dry spell.
Genetic modification
A. aegypti is the subject of investigations that genetically modify the mosquitoes. The
modified strain, known as OX513A, requires the antibiotic tetracycline to develop beyond
the larval stage and passes this trait onto offspring. Modified males raised in a laboratory
develop normally as they are supplied with this chemical and can be released into the
wild. However, their subsequent offspring will find no tetracycline in their environments
and will never develop into adults. An Oxford firm, Oxitec, is performing a pilot program
in Juazeiro, Brazil, to test the effectiveness of these modifications in reducing disease
spread. A 2010 study in the Cayman Islands released of over three million OX513A mosquitoes.
The wild population of mosquitoes subsequently dropped by 80%.
Genomics
The genome of this species of mosquito was sequenced and analyzed by a consortium including
scientists at The Institute for Genomic Research, the European Bioinformatics Institute, the
Broad Institute, and the University of Notre Dame, and published in 2007. The effort in
sequencing its DNA was intended to provide new avenues for research into insecticides
and possible genetic modification to prevent the spread of virus. This was the second mosquito
species to have its genome sequenced in full. The published data included the 1.38 billion
base pairs containing the insect's estimated 15,419 protein-encoding genes. The sequence
indicates the species diverged from Drosophila melanogaster about 250 million years ago,
and Anopheles gambiae and this species diverged about 150 million years ago.
Scientific name The species was first named in 1757 by Fredric
Hasselquist in his treatise Iter Palaestinum. Hasselquist was provided with the names and
descriptions by his mentor, Carl Linnaeus. This work was later translated into German
and published in 1762 as Reise nach Palästina. Since the latter is an uncritical reproduction
of the former, they are both considered to antedate the starting point for zoological
nomenclature in 1758. Nonetheless, the name Aedes aegypti was frequently used, starting
with H. G. Dyar in 1920.
To stabilise the nomenclature, a petition to the International Commission on Zoological
Nomenclature was made by P. F. Mattingly, Alan Stone, and Kenneth L. Knight in 1962.
It also transpired that, although the name Aedes aegypti was universally used for the
yellow fever mosquito, Linnaeus had actually described a species now known as Aedes caspius.
In 1964, the commission ruled in favour of the proposal, validating Linnaeus' name, and
transferring it to the species for which it was in general use.
The yellow fever mosquito belongs to the tribe Aedini of the dipteran family Culicidae and
to the genus Aedes and subgenus Stegomyia. According to one recent analysis, the subgenus
Stegomyia of the genus Aedes should be raised to the level of genus. The proposed name change
has been ignored by most scientists; at least one scientific journal, the Journal of Medical
Entomology, has officially encouraged authors dealing with aedine mosquitoes to continue
to use the traditional names, unless they have particular reasons for not doing so.
See also Mosquito control
References
External links VectorBase's genomic resource for Aedes aegypti
Aedes aegypti page from University of Sydney, Australia
Aedes aegypti and dengue fever United States CDC page on dengue fever containing
information on prevalence of Aedes aegypti worldwide and past efforts to eradicate it
Aedes aegypti on the UF / IFAS Featured Creatures Web site
Walter Reed Hospital Distribution, taxonomy, references etc. Excellent image.
Aedes aegypti at MetaPathogen: taxonomy, life cycle, facts
THE ECOLOGY AND BIOLOGY OF Aedes aegypti AND Aedes albopictus AND THE RESISTANCE STATUS
OF Aedes albopictus AGAINST ORGANOPHOSPHATES IN PENANG, MALAYSIA