With rising temperatures and the return of mosquitoes, one of the most repeated ideas every year also returns: that some people are bitten more because they have “sweet blood”. Recent research points in another direction and suggests that the choice of victims begins long before the bite, with visual and chemical signals that insects detect in the environment.
A study published in March in the journal , led by researchers at MIT and the Georgia Institute of Technology, created a three-dimensional model to predict how mosquitoes fly when searching for a human target. The work focused on females of the species Aedes aegypti and was developed based on controlled experiments and tens of millions of records of its flight paths.
What attracts mosquitoes anyway?
The main conclusion of the study is that mosquitoes do not choose people because of some characteristic of their blood that they would only discover after biting. According to researchers, what guides the approach is the combination of visual cues, such as the contrast of a dark target, and chemical cues, such as carbon dioxide released by breathing. Furthermore, insects do not seem to follow each other: they react individually to the same stimuli and end up converging at the same point.
The model identified three main patterns. When there is only one visual target, mosquitoes make a quick pass and move away if they find no further signs. When they detect carbon dioxide, but without a clear visual target, they slow down and stay in the area looking for the source. When both signals appear simultaneously, they adopt an orbital flight around the target, remaining close and preparing for landing.
In tests with a human volunteer, the researchers also tested the effect of clothing color. The participant entered an observation chamber wearing different colored clothing, including combinations of black and white, while infrared cameras recorded the insects’ movements.
The results, cited by the same source, showed a much greater concentration of trajectories close to dark areas, reinforcing the idea that visual contrast helps transform a person into a more appealing target.
Clothes can weigh more than myth
The does not say that you just need to change your shirt to stop being bitten, but it does show that dark clothing can increase visual attraction, especially when it is accompanied by the release of carbon dioxide. In the case observed by the researchers, the largest clusters were formed around the head and shoulders, areas associated with breathing and where this species usually concentrates its approach.
This helps you understand why two people in the same location might not be approached in the same way. The difference will not be, at least at first, in a supposed “sweet blood”, but rather in the way in which each body becomes more or less visible and detectable to the mosquito, through breathing and the contrast created by clothing.
What this work allows us to conclude
The researchers themselves emphasize that the model could be extended to other factors, such as heat, humidity and odors, to improve traps and control strategies. In other words, the color of clothing and carbon dioxide alone do not explain the entire behavior of these insects, but they appear in this study as two of the most important signs for the initial phase of their approach to humans.
There is also an important note: the work focuses on Aedes aegyptia species associated with the transmission of diseases such as dengue, yellow fever and Zika, and does not allow us to automatically conclude that all mosquitoes behave identically.
Still, the research published in Science Advances offers a more solid and quantitative explanation for an everyday phenomenon that has long been explained based on myths.
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