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Saturday, August 21, 1999 Published at 11:17 GMT 12:17 UK


Mosquitoes use super senses

The insects look for chemicals they are unable to produce themselves

Mosquitoes have the ability to single out who to bite on the basis of the benefit they will derive from consuming the victims' blood.

BBC's Mike Workman: "Research could have important implications"
And the tastiest victims can begin attracting mosquitoes from incredible distances.

These are the claims of scientists at the University of Florida, confirming many people's suspicion that they always get bitten while their neighbours remain untouched.

Entomology Professor Jerry Butler hopes his research will help people protect themselves from diseases mosquitoes carry, including yellow fever and malaria.

Sophisticated smellers

According to Professor Butler, mosquitoes have such a sophisticated sense of smell they can detect tiny amounts of chemicals transferred from the body into the air.

[ image:  ]
The mosquitoes zigzag from molecule to molecule along a thin plume of the chemicals until they home in on their victim.

The insects are looking for chemicals the human body produces - substances like vitamin B or cholesterol - and the more of these a body produces the more likely they are to be bitten by a mosquito.

Professor Butler says that in experiments where a group of subjects are exposed to a large number of mosquitoes, the results are startling.

[ image:  ]
"One person that's repellent may get one mosquito bite whereas the highly attractive person in the group may have several hundred bites," he says.

But his current research relied on more humane experiments. He built an "olfactometer" to measures mosquitoes' preferences for various odours.

The contraption held small plates of blood and other substances covered by a thin membrane to mimic skin. When the mosquitoes pierced the membrane to feed, a computer recorded the strike.

Killing diseases

The research was conducted to explore the tastes of mosquitoes and help humans protect themselves from mosquito-borne diseases.

"If you can drop the feeding rates below some set ratio, somewhere around a 100-to-1, there wouldn't be enough infected mosquitoes to transmit it and the disease transmission would collapse."

Meanwhile, the professor says regular bathing will decrease people's chance of being bitten, as perspiration in which bacteria has had a chance to grow is a clear attraction to mosquitoes.

But skin-care products, used for softening and perfuming the skin, can be an attraction as well.

The key to all of this would be the identification of substances which block the mosquitoes' sense of smell - but research on that is still in its early stages, Professor Butler admits.

But he can recommend one measure already on the basis of his research.

"If you can figure out who among your friends is attractive to mosquitoes and be sure to invite that person to all your outdoor gatherings, you might be able to spare your other guests from mosquito bites."

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University of Florida Entomology and Nematology Department

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