Are you a mosquito magnet? It often seems the tastes of blood-sucking insects favor certain flavors of human over others, but now new research has uncovered that certain soaps can greatly increase and decrease your chances of being bitten by a mosquito.
“It's remarkable that the same individual that is extremely attractive to mosquitoes when they are unwashed can be turned even more attractive to mosquitoes with one soap, and then become repellent or repulsive to mosquitoes with another soap,” said senior author and neuroethologist Clément Vinauger in a statement.
That such a significant effect is seen taps into our unique odor profiles, something we’ve been working to cover up since antiquity, but while a good bubble bath might make us more appealing to our fellow humans, can it change the way biting insects see us?
While everything from blood type (O is very popular) to chemical compounds and cheese have been found to influence how strong a mosquito magnet a person is, mosquitoes are initially drawn in by the carbon dioxide we exhale. Body heat is probably important too, but once the mosquito gets closer, she will respond to the smell of a potential blood source’s skin.
We say she because it’s only female mosquitoes that suck blood as, being full of proteins and amino acids, it’s the ideal prenatal supplement for developing eggs. This is why female mosquitoes only drink blood when they’re developing eggs – the rest of the time they eat plant nectar like the males.
If they like to eat plant nectar, then is covering ourselves in botanicals going to make us more or less of a mosquito magnet? Four humans volunteered to find out by having their odor profiles defined both when unwashed and after they’d washed themselves with four brands of soap – Dial, Dove, Native, and Simple Truth.
“Everybody smells different, even after the application of soap; your physiological status, the way you live, what you eat, and the places you go all affect the way you smell,” says co-author and biologist Chloé Lahondère. “And soaps drastically change the way we smell, not only by adding chemicals, but also by causing variations in the emission of compounds that we are already naturally producing.”
The volunteers each had different odor profiles and some were more appealing to mosquitoes than others. Tests were conducted with live female mosquitoes using fabrics the humans had been wearing so that carbon dioxide exhalation didn’t influence the results.
Washing with Dove and Simple Truth made some of the volunteers stronger mosquito magnets compared to when they were unwashed, but Native soap had a more repellent quality. The researchers wanted to know why, so they analyzed the soaps’ chemical compositions and pinpointed specific ingredients that seemed to be associated with repulsion or attraction.
“With these mixtures, we eliminated all the noise in the signal by only including those chemicals that the statistics were telling us are important for attraction or repulsion,” said Vinauger. “I would choose a coconut-scented soap if I wanted to reduce mosquito attraction.”
The team now plan to test further soaps in the hopes of identifying key attractants and repellents that could help unfortunate mosquito magnets, and explore whether their influence changes throughout the course of the day.
The study is published in iScience.