[Animals] Why are we a mosquito magnet and what can we do to avoid it?

[FNX Magokiler]

Mosquitoes love Kim Zarins. The predilection for insects by Zarins, an English professor at Sacramento State University (United States), is so extreme that her 18-year-old son likes her to go outside with her because it serves as a decoy and "he knows it will be around." saved," says Zarins.

Now, mosquito magnets like Zarins are helping scientists determine what attracts these thirsty bloodsuckers. Along the way, there is new hope for relief.

Beyond being a simple nuisance, mosquitoes can transmit devastating diseases such as Zika, dengue, malaria and West Nile disease, and are responsible for more than a million deaths a year. And although historically they have been more common in tropical climates, mosquitoes carrying pathogenic organisms have expanded their range as the planet warms, including parts of Spain (as recently happened with the tiger mosquito) or the United States.

Mosquitoes use various signals to locate their targets. Scent distinguishes people from other animals, and some mosquitoes have evolved to seek out our unique scent. From a distance of up to 60 meters, they follow the columns of carbon dioxide that we exhale with each breath. As they get closer, they smell the odors emanating from our feet, armpits, and skin. At about 15 meters, they begin to see us as dark silhouettes against the light. Finally, pools of heat guide them to the most suitable places to perch, while the taste receptors in their paws help them decide where to bite.

(Related: Tiger mosquito: Why is it dangerous and what to do if it bites you?)

What mosquitoes like to smell
"It's very surprising how good mosquitoes are at detecting us," says Diego Giraldo, a neuroscientist at Johns Hopkins University (Baltimore, United States) and co-author of a new study that characterizes the human odor profiles that attract Anopheles gambiae, a African mosquito that transmits malaria.

 

 

The work demonstrates, for the first time, that mosquitoes can discriminate between multiple people in a large, spacious setting the size of an ice skating rink. Previous investigations used much smaller cameras and pitted one person against another.

The stage used in Giraldo's experiment was connected to eight tents by air ducts, which channeled the odors of the occupants of each tent onto a heated black disk located in the experimental space. The infrared cameras captured the movements of the mosquitoes that landed on each disk. Throughout the experiment, mosquitoes were four times more likely to land on the disk associated with the subject who attracted more mosquitoes than the subject who attracted fewer. "This shows that, even in complex situations with multiple odor sources, mosquitoes seem to prefer some people more than others," says Giraldo.

Next, the researchers identified the chemicals in each subject's olfactory profile using an instrument capable of separating the gases in the sample into their components. "Human odor, however, is incredibly complex," says Stephanie Rankin-Turner, a chemist at Johns Hopkins University (United States), who also worked on the study. In human odors, "there are a lot of chemical compounds that no one had classified before." To narrow the field, the researchers focused on chemicals known to make up human odor.

Their analysis discovered 15 airborne compounds that were present in the odors produced by all subjects. But it was the concentrations of these substances that determined the likelihood of mosquitoes biting them. "If there is a compound that mosquitoes really like and a person releases a lot of it, it can increase its attractiveness to mosquitoes," Rankin-Turner says.

 

https://www.nationalgeographic.es/animales/2023/06/por-que-somos-iman-para-mosquitos-como-evitarlo