Mosquito

Mosquitoes are a family of small midge-like flies, the Culicidae. Most species are harmless, even useful, but many are blood-sucking nuisances. Some also transmit several of the most harmful diseases of humans and their livestock. Accordingly, some authorities argue that disease-bearing mosquitoes are the most dangerous animals on earth.^[2]

Introduction

Mosquitoes are members of a family of nematocerid flies: the Culicidae (from the Latin culex, genitive culicis meaning midge or gnat).^[3] The word Mosquito is from the Spanish and Portuguese for little fly.^[4] Superficially, mosquitoes resemble crane flies (family Tipulidae) and chironomid flies (family Chironomidae), and as a result casual observers seldom realise that there are important differences between the members of the respective families and also differences between their habits. In particular, many species of female mosquitoes are blood-sucking pests and dangerous vectors of diseases, whereas members of the similar-looking Chironomidae and Tipulidae are not.

Over 3,500 species of mosquitoes have already been described from various parts of the world.^[5][6] Some mosquitoes that bite humans routinely act as vectors for a number of infectious diseases affecting millions of people per year.^[7][8] Others that do not routinely bite humans, but are the vectors for animal diseases, may become disastrous agents for zoonosis of new diseases when their habitat is disturbed, for instance by sudden deforestation.^[9][10]

While eliminating mosquitoes from the planet may sound extreme, a few scientists have suggested that complete eradication would not have serious ecological consequences.^[11][12] In practice, however, control measures focus on the small group of mosquito species which are vectors of human or livestock disease. Some, such as members of the genus Toxorhynchites, actually are beneficial predators of other mosquitoes.

Life cycle

Anopheles larva from southern Germany, about 8 mm long

How to Prevent Mosquito Bites

The perpetually wet and warm climate in Southeast Asia ensures that there is never a shortage of mosquitoes. Ranging from covert ankle-biters to ridiculously sized creatures fit for a horror movie, mozzies - as the Australians affectionately call them - are always looking for a free meal.

 

Aside from being a nuisance while traveling in Southeast Asia, mosquitoes pose two real threats: disease and infection. Scratching mosquito bites with dirty fingernails in a tropical environment can quickly turn a tiny problem into a fever-causing infection. Oozing mosquito bites on legs are a common site found on backpackers in Southeast Asia.

While mosquitoes will probably prove to be only a slight nuisance during your trip to Southeast Asia, the tiny insects are far more nefarious than snakes or any other creature encountered in the wild. The World Health Organization estimates that approximately 20,000 people die per year due to snakebite, but malaria - delivered by mosquitoes - kills more than fifty times that number of people annually. Add other mosquito-borne illnesses to the threat and suddenly humans appear to be loosing the battle. Special care should be given to preventing mosquito bites on your trip to Southeast Asia.

Why do Mosquitoes Bite?

Mosquito Allergy - Reactions to Mosquito Bites

Mosquitoes are flying, biting insects that are closely related to flies and gnats. Only the female mosquito feeds on humans, and she needs a blood meal in order to produce eggs. During a feeding, the female mosquito bites the human skin, and injects saliva. The saliva contains various proteins that prevent the blood from clotting, as well as proteins that keep the blood flowing into the mosquito’s mouth.

Many of the mosquito saliva proteins can cause immune reactions, including allergic reactions. Typically, however, most people have a variety of reactions to mosquito bites, and the symptoms change over time, depending on the amount of bites a person received. These reactions can include both immediate and delayed swelling and itching around the bite area. These reactions tend to decrease in frequency after being bitten by mosquitoes over many years.

Generally, people with the above described reactions are not diagnosed as being “mosquito allergic." This term is reserved for people with more severe or unusual reactions, such as those described below.

More Severe Reactions to Mosquito Bites: "Skeeter Syndrome"

More severe reactions -- rather than the typical itchy red bump experienced by most people as a result of a mosquito bite -- occur less commonly. These may result in blistering rashes, bruises, or large areas of swelling at the bite sites. People who experience extremely large areas of swelling after a mosquito bite (such as swelling of most of an arm or leg, for example) have been dubbed as having "Skeeter Syndrome."

In rare situations, some people may experience anaphylaxis after being bitten by mosquitoes. Other people may have experienced whole body urticaria and angioedema (hives and swelling), or worsening of asthma symptoms after being bitten. Typically, these symptoms occur within minutes after a mosquito bite, compared to Skeeter Syndrome, which may take hours to days to occur.

20 Things You Didn't Know About... Mosquitoes

1  The world’s largest statue of a mosquito is a roadside attraction in Komarno, Manitoba, the Mosquito Capital of Canada. (“Komarno” is Ukrainian for “mosquito.” What’s up with that?) Sculpted in 1984, it is made of steel and has a wingspan of 15 feet. It’s also a weathervane, swiveling in the wind.

2  There are more than 2,500 varieties of mosquito (some entomologists claim 3,000) whining from the Arctic tundra to the tropical rain forests. Most are active at dawn and dusk, while others enjoy midday feeding. Protein is where you find it.

3  In 1998, researchers found a new mosquito species in the London Underground, descended from ancestors that flew in when the tunnels were dug 100 years ago. Once bird-feeders, they now feast on a menu of rats, mice, and people.

4  They rarely interbreed with their aboveground colleagues. Their DNA actually varies from one subway line to another.

5  Mosquitoes do not bite, they suck.

Why Do Mosquito Bites Itch?

Question: Why Do Mosquito Bites Itch?

Most people experience some kind of skin reaction after being bitten by a mosquito. The pain of the bite and the red bump that follows can be tolerated, but the persistent itching is enough to drive you crazy. Why do mosquito bites itch?

Answer:

Only the female mosquito feeds on blood. Though we commonly call them mosquito bites, she's not really biting you at all. The mosquito pierces the upper layer of your skin with her proboscis, a straw-like mouthpart that allows her to drink fluids. Once the proboscis breaks through the epidermis, the mosquito uses it to search for a blood vessel in the dermal layer underneath.

When she locates a vessel, the mosquito releases some of her saliva into the wound. Mosquito saliva contains an anti-coagulant that keeps your blood flowing until she is finished with her meal.

Now your immune system realizes something is going on, and histamine is produced to combat the foreign substance. The histamine reaches the area under attack, causing blood vessels there to swell. It's the action of the histamine that causes the red bump, called a wheal.

But what about the itching? When the blood vessels expand, nerves in the area become irritated by the swelling. You feel this irritation as an itchy sensation.

10 Ways to Guarantee You'll Get Mosquito Bites

Some people are real mosquito magnets. Why do some people seem to attract bloodthirsty mosquitoes from all over the neighborhood, while others can sit outside all evening without suffering a bite? These lucky people give off just the right combination of sights and smells. Mosquitoes use their senses to choose a favorite target in the crowd. Here are 10 ways to guarantee yourself lots of mosquito bites. 

1. Keep breathing.
Mosquitoes detect carbon dioxide in the air, so the more you breathe, the more likely you are to become a blood meal. Carbon dioxide clues the mosquitoes in to the presence of a living, breathing, blood-pumping animal nearby. Once they sense it, mosquitoes usually fly in a zigzag pattern through the CO2 plume until they locate the source.

2. Skip the shower.
That's right, bring on the B.O. The more you stink, the easier it is for a blood-seeking mosquito to find you. Drop the deodorant, skip the soap, and get ready to start slapping skeeters. 

3. Run around.
Mosquitoes first locate potential victims using their sight, and anything moving will be deemed worthy of a second look. Go outside and flag them down. Mow the lawn. Take a jog around the block. Jump up and down and shout "pick me, pick me!" The mosquitoes will pick you, for sure.

4. Sweat a lot.
Perspiration is the perfect combination of mosquito attractants – moisture and odors. Head outdoors on a hot, sticky summer evening, and work up a sweat. The mosquitoes will thank you. 

5. Stay warm.
Think of mosquitoes as heat-seeking missiles. The warmer you are, the quicker they'll find you. Though mosquitoes can't sense your body heat from a distance, once they get within a few yards, your warmth will lure them in. 

6. Dress in dark colors.
Research shows that mosquitoes respond best to dark colors, especially blue. Put away the khakis and white shirt; instead, don your jeans and a black t-shirt. You'll shine a spotlight on yourself that allows the mosquitoes to come in for a quicker landing.

7. Wear perfume or cologne.
If you just can't bear the body odor approach, do the opposite – bathe yourself in the strongest perfume money can buy. Floral scents are especially attractive to mosquitoes. 

8. Use alpha hydroxy products on your skin.
Lactic acid, which our bodies produce naturally, is a big draw for mosquitoes. It just so happens that many skin care products contain lactic acid, too, and so might help boost your chemistry with these blood-seeking bugs. Look for lotions and creams labeled "alpha hydroxy," which provide the most lactic acid. 

9. Don't change your socks.
Yes, this is based on actual scientific research. Mosquitoes love smelly feet. Entomologist Daniel L. Kline experimented with using dirty socks as a mosquito lure, and found his 3-day-old socks were irresistible to them. Specifically, it's the bacteria that grow on human feet that seems to draw a crowd. 

10. Drink beer and eat limburger cheese.
Studies show people who've had a few beers score the most mosquito bites at the barbecue. Snack on some limburger cheese while enjoying a beer, and you will open yourself up to an all out assault. Limburger cheese is made with the same bacteria that makes your feet stink.

Now that you're covered in mosquito bites, you might want to learn how to stop the mosquito bite itch. Have an itch remedy that works every time? Share it.

Source : http://insects.about.com

10 Cool Facts About Mosquitoes

Ah, mosquitoes, the insects that are universally hated the world over. These pesky, disease-carrying pests make a living by sucking the blood out of just about anything that moves, including us. But take a moment to look at things from the mosquito's perspective – it's a pretty interesting life. 

1. Mosquitoes are the deadliest animals on Earth.
That's right, more deaths are associated with mosquitoes than any other animal on the planet. Mosquitoes may carry any number of deadly diseases, including malaria, dengue fever, yellow fever, and encephalitis. Mosquitoes also carry heartworm, which can be lethal to your dog. 

2. Only female mosquitoes bite humans and animals; males feed on flower nectar.
Mosquitoes mean nothing personal when they take your blood. Female mosquitoes need protein for their eggs, and must take a blood meal in order to reproduce. Since males don't bear the burden of producing young, they'll avoid you completely and head for the flowers instead. And when not trying to produce eggs, females are happy to stick to nectar, too. 

3. Some mosquitoes don't bite humans, preferring other hosts like amphibians or birds.
Not all mosquito species feed on people. Some mosquitoes specialize on other animals, and are no bother to us at all. Culiseta melanura, for example, bites birds almost exclusively, and rarely bites humans. 

4. Mosquitoes fly at speeds between 1 and 1.5 miles per hour.
That might sound fast, but in the insect world, mosquitoes are actually rather slow. If a race were held between all the flying insects, nearly every other contestant would beat the pokey mosquito. Butterflies, locusts, and honey bees would all finish well ahead of the skeeter.

5. A mosquito's wings beat 300-600 times per second.
This would explain that irritating buzzing sound you hear just before a mosquito lands on you and bites. 

Bacterium found to kill malaria in mosquitoes

Researchers at the Johns Hopkins Bloomberg School of Public Health have identified a bacterium in field-caught mosquitoes that, when present, stops the development of Plasmodium falciparum, the parasite that causes malaria in humans. According to the study, the Enterobacter bacterium is part of the naturally occurring microbial flora of the mosquito's gut and kills the parasite by producing reactive oxygen species (or free radical molecules). The study is published in the May 13 edition of Science.

"We've previously shown that the mosquito's midgut bacteria can activate its immune system and thereby indirectly limit the development of the malaria parasite. In this study we show that certain bacteria can directly block the malaria parasite's development through the production of free radicals that are detrimental to Plasmodium in the mosquito gut," said George Dimopoulos, PhD, senior author of the study and associate professor at theW. Harry Feinstone Department of Molecular Microbiology and Immunology, and the Johns Hopkins Malaria Research Institute.

Malaria mosquitoes accurately find their way to smelly feet

Malaria mosquitoes utilize CO₂ from exhaled air to localize humans from afar. In the vicinity of their preferred host, they alter their course towards the human feet. Researcher Remco Suer discovered how female malaria mosquitoes use foot odors in the last meters to guide them to their favoured biting place. Suer, who is defending his doctoral thesis May 9 at Wageningen University, part of Wageningen UR, sees possibilities to disrupt the host seeking behaviour of the malaria mosquito.

African malaria mosquitoes, Anopheles gambiae, use their olfactory organs, two antennae, two mouthparts (maxillary palps) and the proboscis, to search for their hosts to obtain a bloodmeal. From a distance of several tens of meters mosquitoes detect CO₂ which forms part of exhaled air by humans. However, a malaria mosquito does not follow the CO₂ trail to its source, the mouth, but at a certain point close to the source is diverted toward the feet, which is the preferred biting place for this mosquito species.

Letting there be more mosquitoes may lead to fewer malaria deaths, say researchers

It may seem counter-intuitive at first but letting mosquitoes grow up and breed may be part of the solution to tackling the devastating impact of malaria. A team of researchers led by Dr Stephen Gourley of the University of Surrey's Mathematics Department have used mathematical modelling to examine why conventional insecticides used against the insects that transmit the disease responsible for millions of deaths a year, can quickly become ineffective in areas of intensive use. Their answers may lead to unprecedented advances in malaria control.

Mosquitoes can become resistant to commonly used insecticides surprisingly rapidly and spraying them while young simply imposes intense selection pressure favouring resistant insects.

Mosquito immune system engineered to block malaria

Researchers at the Johns Hopkins Malaria Research Institute demonstrated for the first time that the Anopheles mosquito's innate immune system could be genetically engineered to block the transmission of the malaria-causing parasite to humans. In addition, they showed that the genetic modification had little impact on the mosquito's fitness under laboratory conditions. The researchers' findings were published December 22 in the online journal PLoS Pathogens.

At left is a normal mosquito from the wild. The three mosquitoes to the right, with glowing eyes, are from three strains genetically engineered to better kill the malaria parasites in their guts. The mosquito at the far right, with yellow eyes, is a hybrid of the two other modified strains and was the most effective of the three at killing the parasite.

Credit: George Dimopoulos/JHU 

 

"The immune system of the Anopheles mosquito is capable of killing a large proportion -- but not all -- of the disease-causing parasites that are ingested when the mosquito feeds on an infected human," said George Dimopoulos, PhD, senior author of the study and associate professor in the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health. "We've genetically engineered this immune system to create mosquitoes that are better at blocking the transmission of the human malaria parasite Plasmodium falciparum."