Summer isn’t over yet, but Labour Day weekend is still for many people the last hurrah for barbecues, beaches, and nights outside. That also makes it prime time for mosquitoes who see this as open season to dine on humans.
If you can’t spend a summer afternoon outside without slapping your ankles — and you still end up with dozens of mosquito bites — then it might be true that the flying pests really do love you.
And those lucky people who say they don’t get bitten? They exist too.
But it’s not because one person’s blood tastes better to the small hovering bloodsuckers — or at least, not just that. In a TED 2014 talk earlier this year in Vancouver, microbial ecologist Rob Knight explained that the bacteria, or microbes, on skin produce different chemicals, some of which smell more attractive to mosquitoes.
The trillion or so microbes that live on skin are a small percentage of the 100 trillion bacteria that live on and inside the body, but they play a huge role in body odor. Without those bacteria, human sweat wouldn’t smell like anything.
However, those different bacteria vary greatly from person to person. Knight explained that while we share 99.9% of DNA with other humans, most people only share about 10% of their microbes.
A siren song for mosquitoes
To demonstrate that mosquitoes are overwhelmingly attracted to certain types of skin microbes, researchers asked 48 adult male volunteers to refrain from alcohol, garlic, spicy food, and showers for two days. The men wore nylon socks for 24 hours to build up a collection of their unique skin microbes.
Researchers then used glass beads that they had rubbed against the underside of the men’s feet to pick up their scent as mosquito bait.
Nine men out of the 48 proved to be especially attractive to mosquitoes, while the scents of seven lucky volunteers were largely ignored. The “highly attractive” group had 2.62 times as high a concentration of one common skin microbe, and 3.11 times higher concentration of another common microbe, compared to the “poorly attractive group.” That poorly attractive group had a more diverse bacterial colony on their skin as a whole.
Researchers say that it’s possible that some people’s smell acts a natural deterrent.
But there’s an equaliser for those that naturally draw swarms of mosquitoes. The same pests are attracted to beer drinkers.
The study was published in the journal PLOS ONE.
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