As soon as the beginning of summer is over, summer officially begins. And mosquitoes, one of the most hated creatures of mankind, are ready to start looking for this year's prey. When a group of people sit together, a mosquito's pet will be born. When the lucky one turns out to be yourself, you will think: why just stare at me and bite? Or can we not bite people and let the family's wealth and Mimi be bitten at the expense of others
You know what? Wearing black clothes is easier to attract mosquitoes
What we may not know is that many mosquitoes do not necessarily have to catch human bites, but will rush up if there is a blood source nearby. However, Aedes aegypti, our most hated "flower mosquito", has found another way and has evolved into a species that specializes in biting humans.
What exactly do they rely on to accurately target humans? A new study in nature found that this may be related to special odor molecules in humans.
Human odors are composed of dozens of different compounds, while the types of compounds in the odors of other mammals may be similar, but the proportion of various molecules is different. For example, the proportion of various seasonings in cooking is different, and the aroma is also different. The proportion of these compounds also creates a special human smell.
But how did Aedes aegypti identify specific molecules? The first thing scientists need to do is collect different odors for analysis and test the response of Aedes aegypti to them.
This is also the most interesting part of this study. The researchers collected the odors of many species such as humans, rats, guinea pigs, quails, sheep and dogs. Most of the odors of animals are obtained from their hair, such as wool donated by the farm, dog hair cut from the pet hospital... And scientists may have to put their hands in the system to attract mosquitoes.
According to Zhao Zhilei, the first author of the study and postdoctoral fellow in neurobiology at Cornell University, the researchers found that even the smell of human daily conditions is enough to attract Aedes aegypti, and mosquitoes are obviously more interested in human taste.
When they wanted to further analyze which compounds in human odor played a role, the researchers made a greater "sacrifice". The researchers didn't take a bath for a few days, then took off their clothes and lay in Teflon bags to collect the smell.
Dr. Zhao Zhilei explained: "in this way, the odor concentration is relatively high, so we can collect a large number of odors for experiments in a short time; in addition, artificial fragrances are often added to shampoo and shower gel, which may interfere with the experimental results."
Because the cotton, polyester or other fibers of clothes will also produce unique odor molecules and affect the actual data, this step must be naked.
In addition to collecting and analyzing odors, the research team also constructed special transgenic mosquitoes. Their brains, such as the olfactory bulb in the primary olfactory brain, emit fluorescence when activated, so that they can observe which neurons are activated when receiving odors.
Subsequently, the study began to test the response of mosquito brains to exposure to different compounds. They had expected that this precise distinction might require the use of most olfactory bulbs, but the results surprised the researchers.
Different odors activate different combinations of olfactory bulbs. However, among many olfactory bulbs, only two are involved in the process of screening human odor. No matter how many human or animal samples are used, the result is so simple.
One olfactory bulb responds to many odors, including human odors, and can guide mosquitoes in the direction of odor; The other olfactory bulb responds only to human odors, but weakly to other mammalian odors. Under this combination, mosquitoes will rush to humans without hesitation.
This olfactory bulb is particularly sensitive to two special molecules, decanal and undecylaldehyde. These two molecules are highly enriched in human odors and less in mammals. Our sebum and metabolism determine this, which makes us the target of Aedes aegypti.
By artificially synthesizing a mixture of the two molecules, the researchers sent it to the wind tunnel, and the mosquito also began to search for a host. Therefore, in theory, if some people have too many metabolites of sunflower aldehyde and undecanoaldehyde, they can easily become the target of mosquitoes.
"There are too few or too many aldehydes that mosquitoes don't like. So theoretically, mosquitoes can interfere with human bites by increasing or reducing the concentration of these two aldehydes in human odors. Of course, there is no mature method to specifically cover up these two molecules," said Dr. Zhao Zhilei
however! If you can't cover up the smell, you can also set up smell traps to catch mosquitoes, which is likely to bring a new generation of mosquito control technology! (looking forward to)
According to Dr. Zhao Zhilei, the study found that the mixture containing decanal in a specific proportion has a strong attraction to mosquitoes. At present, the research team has applied for a patent based on this, mainly using the mixture in mosquito traps to attract and kill mosquitoes. Before it is officially put into commercial use, field experiments need to be carried out to test whether it can also attract mosquitoes efficiently in the wild.
If feasible, it's like the blue light fly catcher seen in restaurants. Maybe there will be no mosquito trouble after installing a small device in the future.