Mosquitoes can detect their victims using infrared radiation

Mosquitoes: They Know How to Find Human Hosts

Male mosquitoes are harmless, but women They need blood for the development of eggs.. How they find their hosts has been studied for a century. During that time, scientists have discovered that there is no single sign which these insects trust.

“The mosquito we studied, Aedes aegypti, is exceptionally experienced For find human owners“, explained the study’s lead author Nicolas DeBeaubien, a UCSB postdoctoral fellow. He also assured that “this work provides a new look at how they achieve this“.

This type of mosquito is used Several signals to detect your victims from a distance. “These include CO₂ from our exhaled air, smellsvision, warmth (due to convection) of our skin and humidity our bodies,” said co-senior author Avinash Chandel, now a postdoc at UCSB.

However, this scientist warns that “each of these signals has limitations“Insects have poor eyesight and a strong wind or rapid movement of the human owner can change the tracking of your chemical senseSo scientists wondered whether mosquitoes could detect a more reliable directional signal, such as infrared light.

They can detect our heat from a distance of about 10 centimeters.

to some 10 centimetersThese insects can detect the warmth emanating from our skin. And they can directly sense the temperature of our skin after landing. These two senses correspond to two of three types of heat transfer: convection, heat transferred through a medium such as air, and conduction, heat through direct contact.

But thermal energy It can also travel long distances when converted into electromagnetic waves, usually in the infrared (IR) range of the spectrum. IR can heat up anything it touches.Animals like vipers can sense the infrared heat of warm prey, and the team wondered whether mosquitoes could do the same.

The researchers put female mosquitoes in a cage and measured them guest search activity in two areas. Each area was exposed to human odors and CO₂ at the same concentrations we exhale. But only one of them was also exposed to infrared radiation from source at skin temperature, about 34°C.

The source was separated from the camera by a barrier that prevented heat exchange by conduction and convection. Then they counted how many mosquitoes they started to feel, as if they were looking for a vein. The result was positive, as it doubled. Search activity of insects.

This means that infrared radiation This is the sense that mosquitoes use to find us.. And the researchers found that it effective up to approximately 70 centimeters“What impressed me most about this work was how strong the IR signal was,” DeBeaubien said.

Infrared radiation itself has no effect.

“But neither signal alone stimulates host-seeking activity,” said Denise Montell, a professor of molecular, cellular, and developmental biology. He added that infrared “only matters in the context of other signals, such as elevated CO₂ and human odor.” In fact, his team found the same thing in tests with infrared alone: it has no effect in itself.

Mosquitoes cannot detect thermal infrared radiation in the same way they detect visible light. the energy is too low to activate rhodopsin proteins which detect visible light in the eyes of animals.

electromagnetic radiation with a wavelength greater than approximately 700 nanometers (nm) does not activate rhodopsinand the wavelength of infrared radiation generated by body heat is about 9300 nm. In fact, no known protein is activated by radiation with such long waves, according to Montell. But there is another way to detect infrared radiation.

This expert noted that the infrared radiation of the Sun has other wavelength than the heat generated by our body, because the wavelength depends on the temperature of the source.

So the authors of the project thought that it was possible the warmth of our bodywhich generates infrared radiation, can collide with certain neurons of the mosquitoactivating them when heated, which would allow them to indirectly detect radiation.