Why do mosquitoes suck the blood out of some of you alive but, somehow, spare the others? To answer this century-old question, scientists built a large, open-air arena — the world’s largest perfumery for mosquitoes as they jokingly call it — with the smells of a half-dozen humans.
New study alert: what attracts these predators in humans the most
Researchers discovered that malaria-carrying mosquitoes are drawn to specific chemicals — carboxylic acid and acetoin — found on human skin.
Mosquito-borne diseases impact about 700 million people per year. Experts predict these numbers to increase with global temperatures rise.
Mosquitos are most def humans’ most lethal predators, carrying diseases such as malaria, yellow fever, and dengue fever that kill more than half a million people each year.
Previous experiments found that pregnant women are more likely to attract mosquitoes. Also, drinking alcohol, exercising, or wearing light-colored clothing. Using certain kinds of soap, even ones that leave behind a smell dominated by a chemical known to repel mosquitoes, paradoxically, increases people’s attractiveness to mosquitoes.
Yet, the exact mix of cues that mosquitoes find most attractive remains a mystery.
The most recent study on mosquito preference was published a month ago in the journal Cell (Current Biology).
For this bloody occasion, scientists built an outdoor testing arena about the size of two tennis courts in Zambia where more than 2,000 people die from malaria each year.
“I like to think of it as the world’s largest perfumery for mosquitoes, where they can choose whose scent they like,” said Conor McMeniman, an assistant professor of molecular microbiology and immunology at the Johns Hopkins Malaria Research Institute, which led the study on mosquito species Anopheles gambiae, a real apex predator of humans.
Scientists watched which hot plates mosquitoes couldn’t resist with an infrared camera. The first thing they found out was: heat and carbon dioxide weren’t enough to attract the insects. Mosquitoes needed the added element of specific human body odor.
Second — and the most important take — the study found that the mosquitoes were particularly attracted to the oily secretions that hydrate our skin (through sweat) and protect it from microbes.
Chemical fatty compounds called carboxylic acids are a strong draw — both in the new study with Anopheles gambiae and in previous work with Aedes aegypti.
The insects were also drawn to acetoin, which is produced by skin microbes too. So, it seems like the skin microbiome is playing a big role in how we smell and how attractive we are to mosquitoes, Rankin-Turner says.
But one individual in the new study whose distinctive body odor mosquitos found relatively unappetizing.
Their signature scent included a low amount of carboxylic acids and high eucalyptols, a substance found in many plants, raising the possibility that diet may play a role. Scientists believe this opened up a new avenue in the search for ways to deter mosquito bites — new products that could mask or alter certain human odors, making it harder for mosquitoes to find human blood and potentially curbing the spread of disease.
Recently conducted tests of four commonly used soaps found that three increased humans’ attractiveness to Aedes aegypti mosquitoes, while one — Native coconut and vanilla body wash — seemed to decrease it, probably because mosquitoes don’t like coconut oil.