How do mosquitoes do to locate you?
In summer, avoiding being the target of mosquitoes often becomes a real nightcloth.However, according to a study published in the journal Current Biology, there is no need to fight: mosquitoes will spot you whatever happens.A team of researchers from the University of Washington and the Institute of Technology of California (United States), thus discovered that the mosquitoes associated three sensory channels to effectively track down their prey.
Thus, the latter would first detect the presence of their host thanks to the carbon dioxide (CO2) which it rejects when it breathes.They would then follow his track and then locate him with the naked eye.Finally, they would spot the hot areas of the body to determine the ideal place to sting.If these means of detection have been known for a long time, it is the first time that the operating mode of mosquitoes has been described.
Several senses analyze the environment simultaneously
To achieve this conclusion, biologists have introduced mosquitoes into a blower.In one case, they injected inside the machine of small CO2 plumes at regular intervals, in order to mimic the breathing of animals with hot blood, that mosquitoes target.In the other case, they injected ambient air, poor in CO2.In accordance with expectations, mosquitoes went to the CO2 source (even if it was 15 meters away), when it was abundant.
The researchers then determined if the mosquitoes used another sensory channel, namely the sight, to identify their victim.To do this, they kept the blower system with or not injection of CO2.Except that in a case, they placed a black object in the blower.This object, contrasting in relation to the rest of the decor, thus simulates the presence of an animal, or a human.After the tests, the biologists then noticed that in the presence of CO2, the mosquitoes spontaneously go to the dark mass.Conversely, they showed no interest in the dark object, when the CO2 concentration was low.
""What is interesting is that there is no CO2 near the object,"" explains Floris Van Breugel, one of the authors of the study in the Eurekalert newspaper.This means that they feel CO2, then leave the plume to fly a few seconds towards the object "".The observation is simple: as soon as CO2 is detected, the eyes of the mosquito take over in order to determine its origin.
The next step was to study the reaction of mosquitoes against a hot object (at 37 ° C) placed in the blower.Unsurprisingly, mosquitoes were more interested in the object at 37 ° C than an object at room temperature.More surprising on the other hand, this preference was present even when the concentration of CO2 was low.These two ways to track down the prey are therefore independent.However, according to scientists, the mosquito first uses its sight, because it sees the target before detecting its heat, which they spot when they are less than a meter from their prey.
A precise and tied operating mode
Following these experiences, the researchers were able to reconstruct the mosquito hunting strategy.Beyond 10 meters, the insect first detects its prey thanks to the CO2 which it rejects while breathing.Then, between 10 and 5 meters, they use their sight to identify dense objects, where the breathing could come.It is only when the mosquito is sufficiently close to his host that he then begins to perceive his thermal signature and the humidity that he gives off, ensuring that he targets a living being well, and not a rock.At less than 20 cm, this thermal signature allows the mosquito to identify the hottest, more irrigated areas.The insect then only has to get to the table.
With such a detection system, escaping mosquitoes is almost a feat.""Even if it was possible to retain his breathing indefinitely, another human who breathes nearby creates a CO2 plume which can lead mosquitoes close enough to you to see you, conclude the authors of the study.The best defense is therefore to become invisible or then camouflage oneself.However, even in this case, mosquitoes will always be able to locate you thanks to the thermal signature of your body.""
In short, if it is possible to neutralize one of the senses of the mosquito, it is, however, difficult to fuck them all.Some factors even multiply your chances of being spotted by a mosquito.Pregnant women are thus privileged targets: their bodies reject more CO2 than other people and has a greater blood circulation.
However, it is not only the heat, your shape or your breathing that a mosquito can detect.Indeed, more than twenty odors secreted by our skin would stimulate their smell.The presence, or not, of certain bacteria on our skin could participate in the development of this fume.A recent study even established a genetic origin for the unreasonable attraction experienced by mosquitoes for some of us.
