Summer is on the way, and in many parts of North America that means dealing with annoying mosquitoes at home and in campgrounds. Why some people are so attractive to the tiny blood suckers could be because of the soap they use.
The pesky insects are drawn to people who use soaps such as Dial, Dove and Simple Truth but are put off by coconut-scented brands, including Native, say scientists at Virginia Tech.
Mosquitoes may fly towards or away from specific aromas once they get a whiff of human skin.
Senior author Dr. Clement Vinauger said: “It’s remarkable 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.”
Theories abound for why some people are mosquito magnets while others get off bite-free.
Co-author Dr. Chloe Lahondere explained: “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.
“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.”
A series of experiments found soap-washing impacted mosquitoes’ preferences depending on types.
Chemicals emitted by four human volunteers were analyzed both before and an hour after they’d scrubbed with Dial, Dove, Native and Simple Truth. Odor profiles of the soaps themselves were also characterized.
Each participant emitted their own unique odor, some of which were more attractive to mosquitoes than others. Soap-washing significantly changed these and not only by adding floral fragrances to the mix.
The tests were carried out using female Aedes aegypti. Like all mosquito species, only females drink blood. Bites from A. aegypti can transmit dengue, yellow fever, chikungunya and Zika.
Effects of exhaled carbon dioxide (CO2)—another important cue for mosquitoes—were excluded by conducting them on fabric that had absorbed the participants’ odors.
HUMANS CAN’T SMELL CO2, which we and other animals exhale. Mosquitoes can. It boosts females’ activity—making them explore surrounding space in search of a host.
Vinauger said: “What really matters to the mosquito is not the most abundant chemical, but rather the specific associations and combinations of chemicals, not only from the soap, but also from our personal body odors.
“All of the soaps contained a chemical called limonene which is a known mosquito repellent but in spite of that being the main chemical in all four soaps, three out of the four soaps we tested increased mosquitoes’ attraction.”
The study reported in iScience identified four chemicals associated with mosquito attraction and three with repulsion, including a coconut-scent in American Bourbon and a floral compound used to treat scabies and lice.
They were combined to create and test attractive and repellent odor blends—which had strong impacts on mosquito preference.
Vinauger said: “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.
“I would choose a coconut-scented soap if I wanted to reduce mosquito attraction.”
He now plans to expand the results and find some general patterns or rules by testing more soap varieties and many more people—and explore how soap impacts mosquito preference over a longer period of time.
Vinauger said: “We’re very curious to look at the time course of this effect—so for example, if you take a shower in the morning, does it still matter to mosquitoes in the evening?”
I know how to avoid getting bit, I take my wife along as they love her.
Only four people involved in the study? This is bogus.
And all 4 probably work for big coconut. The coconut lobby is very powerful. In the old days, sample size was pretty important for a study to hold any (coconut) water.
What about blood type? There have been studies that indicate they are attracted to O+ and tend not to be attracted to A+/A-
I would think if that’s true, the study on scent would include that.
I’m willing to try anything because mosquito bites can effect me for weeks. Coconut it is.
I’m blending up a Pina Colada, removing my shirt (TMI) right now and putting on coconut sunscreen. I too get infections that last for weeks from the little buggar’s bites. I thought it was only me. Good luck.
Also eating bananas makes you sweat an attractant to mosquitoes.
I wonder if coconut scented sunblock had the same effect…?
Now this research is the kind that I would be happy for my federal income tax to support mightily!