Mosquitoes are the natural enemy of beautiful summer evenings. No matter what you do, they find their goal. Their antennas can locate us from 50 meters away. Researcher Pie Müller knows what tricks they still have up their sleeve.
SRF knowledge: Mr. Müller, how do mosquitoes actually find their victims?
Pie Müller: With a whole range of sensory organs. With their antennae, mosquitoes perceive the CO₂ that we exhale at a distance of up to 50 meters. When they get a little closer, they detect our body odor with their antennae. Smells are important, even though mosquitoes don’t have a nose.
From about half a meter to a few centimetres, body heat and humidity also play a role, as does the sense of touch and taste once they have landed. Mosquitoes can taste with their feet, just like flies.
What Makes Mosquito Sprays Repellent To Mosquitoes?
To this day we do not know exactly why these funds work. We know they work, but we don’t know the exact mechanism in detail. Our analyzes show that they land briefly despite the spray, but then fly away again (see video).
If you don’t know how it works, how do you find active ingredients for the sprays?
There are two approaches. Either the principle of home remedies: one builds on natural substances whose effects are traditionally known and develops them further. Or you can test large collections of active ingredients. Thus, by trial and error, one finds molecules that have a deterrent effect.
How do you study the sensory perception of mosquitoes?
There are different methods. Take electrophysiology, for example: it can be used to measure where the nerve signals occur when a certain stimulus occurs. Or we can turn off certain genes and then see what’s no longer working. That’s how we get to the bottom of things.
Why are some people more likely to be victims of mosquitoes than others?
The myth of “sweet blood” is wrong. But evidence shows that some people are more attractive to mosquitoes than others. This has something to do with body odor, for example, or with body temperature: the warmer, the more attractive.
We know that pregnant women become more attractive to malaria mosquitoes.
Diet plays a role – lots of alcohol attracts mosquitoes. We also know that pregnant women become more attractive to malaria mosquitoes. We are still groping in the dark as to why this is so.
Are mosquitoes differently aggressive in different regions?
There are around 3,600 species of mosquitoes worldwide. Some only bite humans, some only bite animals, and some are not picky between humans and animals.
Mosquitoes that specialize in humans are particularly effective at finding humans. If they are active during the day and are therefore easier to spot, they probably prefer to bite shorter but more frequently. That looks more aggressive. In Switzerland we know about 40 species. Here, too, there are those that only sting people.
Mosquitoes are proverbial flyweights and can still pierce our skin. How do you do that?
Mosquitoes have a sophisticated biting device that consists of different elements. One of them has teeth on the bottom, a kind of jigsaw. The skin is thus cut rather than punctured. Other elements spread the skin while another needle taps the blood vessel and sucks the blood like a straw.
The interview was conducted by Thomas Kobel.