Mosquito magnets have their own irresistible skin aroma to blame

SOME people are mosquito magnets because they produce chemicals that attract the blood-sucking insects, scientists have found.

A study by scientists at Rockefeller University in the US discovered that those bitten more than others had higher levels of carboxylic acids on their skin. These chemicals are natural skin secretions but vary in concentration from person to person.

Scientists had speculated that some people were bitten more often than others because something was attracting them, or repelling them and the new study, published in Cell, found it was the former.

Three people who took part in the study wore nylon stockings on their forearms as they went about their daily business. Researchers put the stockings in a box with mosquitos to see if the insects preferred some to others and one person in the study’s arm wear was found to be the most desirable.

Further recruitment of sweat donors led to eight people entering into a “round-robin style ‘tournament” to find whose body fluids were the most and least attractive to mosquitos.

The super-attractor from the initial group was found to be four times as attractive to the mosquitos as the next most inviting, and 100 times more enticing than the two people in whom the mosquitos had no interest.

“We provide empirical evidence that mosquitoes strongly prefer some people over others and that the olfactory cues that make some people ‘‘mosquito magnets’’ are stable over many months,” the researchers write.

Chemical analysis of the nylon sleeves revealed the difference in mosquito desirability corresponded to wide variations in the level of around 50 chemicals, mainly carboxylic acids. A second study to prove the findings on 64 people corroborated the theory.

Researchers say the findings were “remarkably stable over many months”, indicating little can be done to alter levels mosquito-attracting scent.

“The best thing … is to apply a repellent, such as DEET, to the skin, since this compound somehow overrides the many attractive signals that direct the mosquito to bite our skin,” said Dr Maria Elena De Obaldia, the study’s lead author. “Trying to “dampen” or “remove” attractive cues might work, she added. But this may not work because humans emit many types of cues: CO2, body heat, and many compounds that make up skin odour.