Scientists make major discovery in war against mosquitos – and it could be the key to a bite-free holiday
WHY some people are mosquito magnets could be down to which soap they use in the shower, according to new research.
The pesky insects are drawn to people who use certain soaps, suggesting picking the right soap can help us steer clear of the critters that leave an itchy bite.
Mosquitos were drawn to those who used Dove or Simple Truth but were put off by coconut-scented brands – including Native, say scientists.
They fly towards or away from specific aromas – once they have got 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.”
Avoiding the blood suckers this summer may hinge on making the right choice of attire to cover your skin, said the team at Virginia Tech in the US.
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 analysed both before and an hour after they’d scrubbed with Dial, Dove, Native and Simple Truth.
Each participant emitted their own unique odour – 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.
Effects of exhaled carbon dioxide (CO2) – another important cue for mosquitoes – were excluded by conducting them on fabric that had absorbed the participants’ odours.
Humans can’t smell CO2, which we and other animals exhale with each breath. Mosquitoes can.
It boosts females’ activity – making them explore surrounding space in search of a host.
Dr 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 odours.
“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.”
Knowing what lures the hungry pests also opens the door to developing better repellents, traps and other methods to keep them at bay.
Dr Lahondere said: “We know ratios of chemicals are extremely important for determining whether mosquitoes are attracted or repelled.
“Changing the ratio of the same exact chemicals can result in attraction, indifference, or repulsion.”
The study 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 odour blends – which had strong impacts on mosquito preference.
Dr 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.
Dr 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?”
HOW ELSE TO PREVENT BITES
Mosquitoes are found everywhere in the world but they thrive most in hot and humid places.
A bite is relatively harmless, albeit very itchy.
But in some countries, there is the risk of getting bitten by a mosquito carrying malaria, dengue fever or yellow fever.
These can have serious consequences.
Mosquitoes which transmit Zika, dengue and chikungunya infections bite predominantly during the daytime and at dusk, while those passing malaria bite at night.
If you are travelling somewhere far, seek advice from your local GP, practice nurse or a travel clinic, ideally four to six weeks in advance of your trip, to get advice, the Government says.