Biologists have found substances by which mosquitoes recognize human smell

(ORDO NEWS) — American scientists have identified volatile molecules that allow mosquitoes to distinguish people from other animals, and showed how the tiny brain of insects recognizes the smell of the victim.

The vast majority of mosquitoes are generalists, ready to drink the blood of any suitable animal. However, some Aedes aegypti , carriers of a number of dangerous diseases, specialize specifically in humans, unmistakably finding their target. Scientists have already managed to identify receptors in the antennae of these insects, which allow them to recognize a person.

But what exactly are the volatile components that help distinguish human odors from other animal odors? And how exactly does the insect brain recognize them? The new work of biologists from Princeton University (USA), which they write about in the journal Nature , is devoted to answering these questions .

Carolyn McBride and her team have obtained a GM line of mosquitoes, which have been introduced genes for fluorescent proteins that are activated in neurons during their work. In addition, a laboratory setup had to be set up to monitor this activity in response to odors.

Finally, the scientists collected the odors themselves for research: 16 volunteers of both sexes were responsible for the human odors, and animal odors were obtained from rats, hamsters, partridges, sheep and dogs.

Experiments have shown that recognition of the smell of people in Aedes aegypti is extremely simple and effective. The “brain” of these insects contains 60 nerve ganglia, and at first, scientists expected to see complex patterns of their activity that occur in response to certain scents.

However, only two nerve centers were activated: one – at the appearance of any potentially interesting smell, including animals, and the second “confirmed” the presence of a person.

These scents are a complex mixture of dozens of volatile compounds that both humans and animals have, only in slightly different proportions.

By painstakingly sorting through such molecules one by one, the scientists showed that only two of them trigger the second “recognizing” ganglion in mosquitoes. These are two long-chain aldehydes, decanal and undecanal, which are especially rich in human odor.

Professor McBride and her co-authors have already patented an attractant formulation containing decanal to attract insects into traps. According to scientists, such traps, imitating the smell of a person, will help fight dangerous bloodsuckers, but at the same time they will be relatively safe for other insects.

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