Mosquitoes have evolved to ensure that they can always smell humans

NEW YORK — Thanks to evolution, mosquitoes will always be pests that people have to deal with, a new study reveals. Researchers have found that receptors in mosquitoes’ antennae can detect the smell of humans. However, even when scientists remove those antennae, the pesky insects can still find us!

“Mosquitoes are breaking all of our favorite rules of how animals smell things,” says lead author Margo Herre, a scientist at Rockefeller University, in a media release.

In most animals, humans included, specific neurons in the nose can detect certain smells. When you lose one of them, you lose the ability to pick up the specific smell it reacts to.

“If you’re a human and you lose a single odorant receptor, all of the neurons that express that receptor will lose the ability to smell that smell,” adds senior author Leslie Vosshall from the Howard Hughes Medical Institute.

The research, published in the journal Cell, shows that this is not the case with mosquitoes.

The study found that the neurons used to find humans are stimulated not just by the human smell but by another chemical in mosquitoes called amines. Having more than one stimulant means that if one is destroyed the other can kick in to help find their target. This co-expression of receptors acts as a “fail safe” for mosquitoes.

Mosquito antenna with fluorescently labeled olfactory neuron
Mosquito antenna with fluorescently labeled olfactory neurons. (Credit: Rockefeller University)

By looking specifically at isolated nuclei, instead of the entire cell, scientists discovered how common this is in mosquitoes.

“You need to work harder to break mosquitoes because getting rid of a single receptor has no effect,” says Vosshall. “Any future attempts to control mosquitoes by repellents or anything else has to take into account how unbreakable their attraction is to us.”

“The result gave us a broad view of just how common co-expression of receptors is in mosquitoes,” says Olivia Goldman, another lead author of the paper.

This doesn’t just happen with mosquitoes. A research group, led by Christopher Potter at Johns Hopkins University, reports that fruit flies have the same ability.

“This may be a general strategy for insects that depend heavily on their sense of smell,” Vosshall concludes.

South West News Service writer Alice Clifford contributed to this report.

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