Mosquitoes are the world's deadliest insects, responsible for millions of deaths and tens of millions of sick people every year.
They do this indirectly, by carrying viruses and other parasites that cause often deadly diseases like dengue and malaria. For this reason, finding a way to prevent bites is essential to saving millions of lives. But to do so, it is essential to understand how mosquitoes identify us.
Decades of research have taught us that they don't use a single stimulus, but a combination of information that activates different senses: the presence of CO2, for example, our smell, body moisture, and now, as documented by a study published in Nature, we can add another trick. Mosquitoes can find us by following the infrared rays emitted by our skin.
The mosquitoes used in the study are perhaps the most dangerous in the world, those of the Aedes aegypti species, also known as the yellow fever mosquito. These insects use a combination of stimuli to locate us, but we know that each of these stimuli, alone, is not enough for mosquitoes to find us. It is not enough for them to find us by sight alone, in some cases a slightly strong smell is enough to confuse their chemical identification system.
Knowing that these mosquitoes also use the heat emitted by our bodies, the team from UC Santa Barbara, California, set out to test their ability to detect infrared radiation, which can cover greater distances than direct heat.
The team divided mosquitoes into two groups, both exposed to a combination of heat, wind, CO2 and all the other elements these insects use to find us. One of the two groups was also exposed to an infrared source at 34°C (the temperature of the surface of our skin). Mosquitoes in this group doubled their efforts to find prey to bite.
It's the first time infrared has been found to have an effect on mosquitoes. Previous experiments have used it alone, never combined with other sensory stimuli. In other words, infrared by itself has no effect, but if you add humidity, scents and CO2, they become another element that mosquitoes use to figure out where to bite.
This new discovery could be used to devise new methods for preventing bites, which could save millions of lives.
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