How human-biting mosquitoes track us down so effectively isn’t currently known, but it matters, since they don’t just make us itch. They also carry dangerous diseases such as Zika, dengue, West Nile virus and malaria that can be deadly.
In fact, stopping these pesky insects in their tracks could save up to half a million lives lost to those diseases each year.
“In each of those cases where a mosquito has evolved to bite humans — which has only happened two or three times — they become nasty disease vectors,” said Carolyn “Lindy” McBride, an assistant professor of ecology and evolutionary biology at the Princeton Neuroscience Institute in New Jersey.
That’s why she wants to understand how they find and target humans.
Mosquitoes can smell us
“Mosquitoes mostly choose what to bite based on odor,” said McBride, whose lab focuses on the Aedes aegypti mosquito species that evolved to bite humans specifically.
Only female mosquitoes suck blood since they need it to produce their eggs. Knowing how a potentially disease-carrying female mosquito sniffs out a person, while ignoring other warm-blooded animals, is a key query.
Once that’s better known, much more effective repellents — or bait to lure mosquitoes away from humans — could be made, saving lives, said Christopher Potter, associate professor of neuroscience at Johns Hopkins University’s Center for Sensory Biology.
If scientists can control their sense of smell, “we can really control what these mosquitoes are doing,” said Potter, who studies another human-specific mosquito, Anopheles, which carries malaria.
Our odors are complicated
It’s not an easy question to answer, since any animal smell is made up of hundreds of chemical compounds mixed together in specific ratios.
Each time a hungry female mosquito flies by, it’s doing complex chemical math in its tiny brain, figuring out what’s a human, what’s dog and what’s a flower.
A library of smells
McBride’s lab team created a library of the chemical composition of animal odors. “That data set doesn’t really exist — so we decided to go out and collect it ourselves,” said Jessica Zung, a graduate student in McBride’s lab.
Zung has collected scent samples from about 40 different animals so far, including guinea pigs, rats, quail and more.
One common compound stood out
Comparing some of those to the 16 human samples, something jumped out. Decanal, a simple, common compound, is particularly abundant in human skin, Zung said.
Read More News: Understanding how mosquitoes smell humans could save human lives