Mosquito Culicidae
Few animals on
Earth evoke the antipathy that mosquitoes do. Their itchy, irritating bites and
nearly ubiquitous presence can ruin a backyard barbecue or a hike in the woods.
They have an uncanny ability to sense our murderous intentions, taking flight and
disappearing milliseconds before a fatal swat. And in our bedrooms, the
persistent, whiny hum of their buzzing wings can wake the soundest of sleepers.
Beyond the nuisance factor, mosquitoes are carriers, or vectors,
for some of humanity’s most deadly illnesses, and they are public enemy number
one in the fight against global infectious disease. Mosquito-borne diseases
cause millions of deaths worldwide every year with a disproportionate effect on
children and the elderly in developing countries.
There are more than 3,000 species of mosquitoes, but the members
of three bear primary responsibility for the spread of human diseases.
Anopheles mosquitoes are the only species known to carry malaria. They also
transmit filariasis (also called elephantiasis) and encephalitis. Culex
mosquitoes carry encephalitis, filariasis, and the West Nile virus. And Aedes
mosquitoes, of which the voracious Asian tiger is a member, carry yellow fever,
dengue, and encephalitis.
Mosquitoes use exhaled carbon dioxide, body odors and
temperature, and movement to home in on their victims. Only female mosquitoes
have the mouth parts necessary for sucking blood. When biting with their proboscis,
they stab two tubes into the skin: one to inject an enzyme that inhibits blood
clotting; the other to suck blood into their bodies. They use the blood not for
their own nourishment but as a source of protein for their eggs. For food, both
males and females eat nectar and other plant sugars.
Mosquitoes transmit disease in a variety of ways. In the case of
malaria, parasites attach themselves to the gut of a female mosquito and enter
a host as she feeds. In other cases, such as yellow fever and dengue, a virus
enters the mosquito as it feeds on an infected human and is transmitted via the
mosquito’s saliva to a subsequent victim.
The only silver lining to that cloud of mosquitoes in your
garden is that they are a reliable source of food for thousands of animals,
including birds, bats, dragonflies, and frogs. In addition, humans are actually
not the first choice for most mosquitoes looking for a meal. They usually
prefer horses, cattle, and birds.
All mosquitoes need water to breed, so eradication and population-control
efforts usually involve removal or treatment of standing water sources.
Insecticide spraying to kill adult mosquitoes is also widespread. However,
global efforts to stop the spread of mosquitoes are having little effect, and
many scientists think global warming will likely increase their number and
range.
sumber : http://animals.nationalgeographic.com/animals/bugs/mosquito/
