Mosquitoes are a nuisance that buzzes and stings in summer, and they are also deadly animals for us, due to the transmission of viruses and parasites. In the first world they do not seem like something to worry about, but there are countries where thousands of people die because of these small insects.
Some species of these flying killing machines feed exclusively on humans, but to be so successful, they must have evolved precise targeting mechanisms to distinguish between human and animal scent.
Now researchers are finally figuring out how they do it, and a new study published in Nature may answer the question: What do mosquitoes detect and how do they do it? Here are some tricks for home.
“We got right into the brain of the mosquito and asked it: What can it smell? What lights up your brain? What activates your neurons? And how does your brain activate differently when you smell human scent and animal scent?“. They explain in a statement.
The team created genetically modified Aedes aegypti mosquitoes – vectors of Zika virus, dengue virus, yellow fever virus and chikungunya virus – using CRISPR-Cas9.
These transgenic insects had brains that lit up when active, allowing scientists to image the brains at high resolution. Then, the researchers supplied human- and animal-flavored air to these mosquitoes through a wind tunnelto determine what the insects liked.
Human scent is made up of many different compoundsand these same compounds are also present in most mammalian odors, but in different proportions.
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Previous research has found that the compounds alone are not attractive to mosquitoesso one of the challenges is to determine the exact proportions of the attractant compounds.
The team used scents from 16 humans, two rats, two guinea pigs, two quail, one sheep and four dogs to whet the mosquitoes’ appetites. The way they collected these samples was quite interesting.
For the sheep, they had a farm donate several fleeces, and for the dogs, they visited a hair salon and collected trimmed hair from the adorable dogs.
“For the human samples, we had a lot of volunteers.said study author Jessica Zung.We made them not shower for a few days, then they stripped naked and lay down in a Teflon bag“.
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Once they recovered all these odours, they designed a clever system to blow the odor away from the genetically modified mosquitoes in the area where the images were installed.
The mosquito brain has 60 nerve centers called glomeruli, and the team originally hypothesized that most of these centers would be involved in helping the mosquito find its next meal and distinguish human from animal scents, but it turned out to be the opposite.
Through the experiments, it was determined that mosquitoes detect two chemical substances (decanal and undecanal)which are enriched in human odor and likely originate from lipids unique to human skin rather than sweat.
Overall, this exciting collaborative research can help the development of new repellents more effective than the current ones.
George is Digismak’s reported cum editor with 13 years of experience in Journalism