- A new study could answer the question: What do mosquitoes detect and how do they detect it?
Image of a mosquito of the Aedes aegypti species. / Pixabay
Mosquitoes are a nuisance because of their buzzing and biting sounds, but they are also the most deadly animals for 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 scents. Now researchers are finally figuring out how they do it, reports IFL Science.
A new study published in Nature could answer the question: What do mosquitoes detect and how do they detect it?
"We dove into the mosquito brain and asked, 'What can you smell? What's lighting up your brain? What's firing your neurons? And how does your brain fire differently when you smell human versus animal scents? ?'" 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 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 in high resolution. 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 the compounds alone are not attractive to mosquitoes, so determining the exact ratios of the attractive compounds is a challenge.
The team used the scent of 16 humans, two rats, two guinea pigs, two quail, one 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.
We asked them not to take a bath for a few days, then they undressed and lay down in a Teflon bag.
"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 of these odors, they designed a clever system to inject the genetically modified mosquitoes with an odor into the imaging setup area.
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 all that contrary.
"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, and 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 by human odor and likely originate from unique human skin lipids rather than sweat.
Overall, this collaborative research can help the development of new repellents, allowing us all to enjoy the nice outside air without the fear of these nasty bugs stealing our blood.