Do you know why mosquito bites itch?

Prof. Know Why answers:

Mosquitoes are the familiar flying insects belonging to the family of Culicidae. There are about 2,500 known species of mosquitoes in the whole world. Mosquitoes are particularly dangerous insects since they are known to transmit such serious diseases as yellow fever, malaria, filariasis dengue and Japanese B encephalitis.

Mosquitoes generally bite at any time, but prefer the evening. And, do you know that only the female mosquitoes bite? Yes! The male mosquitoes, and sometimes the female mosquitoes, feed on nectar and other plant juices. But in most species the female mosquitoes require a blood meal to acquire protein, needed to produce eggs. Female mosquitoes lay multiple batches of eggs during their lifespan, and a new blood meal is needed to produce every batch. Different mosquito species prefer different host species. Some mosquitoes seek blood meals from birds, while other mosquitoes love mammals. And some are generalists.

But why do mosquito bites itch? The female mosquito inserts her needle-like proboscis (a slender, tubular, feeding and sucking organ) into the victim's skin, to draw blood. She sucks until her abdomen is full. But doing that is not easy as blood clots very quickly (on contact with air) to have a drink. So, the mosquito injects her saliva, containing digestive enzymes and anticoagulants that stop the blood from clotting. Our body sees that as an enemy and produces and sends chemical called histamines to the injected area, to ward off infection. And, it’s the reaction between histamines and the saliva of the mosquito that causes the itching, swelling and redness.

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• Do you know why mosquitoes bite certain people?

Do you know why mosquitoes bite certain people?

Prof. Know Why answers:

It’s strange, but amazingly true that mosquitoes may not bite all the people in the same place. And only a selective set of people may fall prey to these tiny blood suckers that put millions of lives at stake by spreading malaria - the most prevalent life-threatening disease in the world. Scientists have worked out the answers why and how mosquitoes make a beeline for certain people and leave others almost untouched.

Specific cells in one of the three organs that make up the mosquito’s nose are tuned to identify the different chemicals that make up human body odor. To the mosquito, some people’s sweat simply smells better than others because of the proportions of the carbon dioxide, octenol and other compounds that make up body odor. It’s those people who are most likely to be bitten.

Mosquitoes use three organs to smell and taste – a feathery antenna which can identify a wide range of different chemicals, a proboscis used for short range detection and the maxillary palp for longer range smelling.

Scientists have found that maxillary palp contains a series of highly specialized receptor cells used to detect the different components of human body odor. Professors of biological sciences believe, mosquitoes are good transmitters of malaria because they are extremely good at finding people to bite, and maxillary palps serve as the malaria mosquito’s long range detection system.

So, if you think you are the mosquito’s delight, better take care!

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