Mosquitoes are a nuisance because of their buzzing and pecking sounds, but they are also the deadliest animals to humans, due to the transmission of different viruses and parasites.
Some species of these flying killing machines feed exclusively on humans, but to be such a successful feeder, they must have evolved precise targeting mechanisms to distinguish between human and animal odor. Now researchers are finally figuring out how they do it, collect IFL Science.
A new study published in Nature could answer the question: What do mosquitoes detect and how do they detect it?
“We dived into the brain of the mosquito and asked, ‘What can you smell? What lights up your brain? What is activating your neurons? And how does your brain activate differently when you smell human scent versus animal scent?’”Carolyn McBride, an assistant professor of ecology and evolutionary biology and neuroscience, said in a statement.
This is how the experiment was done
The team created mosquitoes Aedes aegypti genetically modified 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 Obtain high-resolution images of the brain. The researchers then fed human- and animal-scented air to the mosquitoes through a wind tunnel to determine what attracted the insect’s attention.
Human odor is made up of many different compounds, and these same compounds are also present in most mammalian odors, but in different proportions. Previous research has found that compounds by themselves are not attractive to mosquitoes, so a challenge is to determine the exact proportions of the attractive compounds.
The team used the scent of 16 humans, two rats, two guinea pigs, two quails, a sheep and four dogs to stimulate the mosquito’s appetite. 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 grooming salon and collected clipped dog hair.
“For the human samples, we had a lot of great volunteers”said study author Jessica Zung. “We asked them not to bathe for a few days, then they undressed and lay down in a Teflon bag»adds the researcher. Once they recovered all these smells, designed an intelligent system to insufflate the genetically modified mosquitoes scent into the imaging setup area.
mosquitoes
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 the opposite turned out.
“When I first saw the brain activity, I couldn’t believe it, only two glomeruli were involved”said Zhilei Zhao, a member of the research team. “That contradicted everything we expected, so I repeated the experiment several times, with more humans, more animals. I just couldn’t believe it. It’s so simple»Zhao added.
Through experiments, it was determined that mosquitoes detect two chemicals (decanal and undecanal), which are enriched with the human scent and they probably originate from lipids unique to human skin rather than sweat. In general, this collaborative research it can help the development of new repellants, allowing us all to enjoy the pleasant outside air without the fear of these nasty insects stealing our blood.
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Reference article: https://www.20minutos.es/noticia/4996706/0/ciencia-descubre-como-localizan-mosquitos/
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