A pleasant summer evening in the fresh air can easily turn into a nightmare because of mosquitoes – once one of them has feasted on human blood, an invasion cannot be avoided. True, mosquitoes do not feast on everything, and among more than 3,500 species of these insects, only a few “hunt” for people. Only females drink blood, since they need it as a source of protein for eggs. Interestingly, when biting, insects pierce the skin of the chosen “victim” with their needle-like proboscis, as a result of which the affected area of skin can begin to itch and swell. Moreover, in many countries of the world, mosquitoes are carriers of dangerous diseases. But even if the bite is not associated with the risk of contracting malaria or another infection, itching and swelling in the affected area of the skin can cause discomfort for several days. But is it true that mosquitoes don't suck the blood of everyone, but carefully choose their victims? Let's find out!
If you feel like you're getting bitten by mosquitoes more often than others, you probably are! Image: d.newsweek.com
Contents
- 1 Choosing a Mosquito
- 2 Carbon Dioxide
- 3 Blood Type
- 4 Temperature
- 5 Bacteria on the Skin
- 6 Who Doesn't Get Bitten by Mosquitoes?
Choosing a Mosquito
The first studies on mosquito preferences were conducted back in the 1970s, and their results showed that these blood-sucking insects really do prefer some people over others. One scientific paper even suggested that about 20% of people are more attractive to mosquitoes. However, the reasons for this choice of insects are only partially understood, and they are quite contradictory.
Thus, some scientists believe that there are several factors that turn a person into a kind of “mosquito magnet”, including exhaled carbon dioxide (CO2), odor and body temperature. And anything that can somehow change these factors affects mosquito preferences.
The results of several scientific studies have shown that mosquitoes do have preferences regarding what they land on and what they feed on. Image: i.natgeofe.com
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Their opponents, in turn, argue that although mosquitoes rely on these universal factors, the choice of the most “tasty” person depends on more specific combinations. The main factor, however, is the carbon dioxide (CO2) that we exhale – it is by its plume that insects navigate, determining the location of victims. But first things first.
Carbon dioxide
Humans, like almost all other animals, exhale CO2, heat and moisture, which initially attracts mosquitoes, whose females detect the carbon dioxide (as well as other human skin odors) using highly sensitive nerve cells. A study published in the journal Plos One suggests that the more CO2 a person exhales, the more mosquitoes are attracted to them.
Mosquitoes react to CO2, using it to determine the location of the victim. Image: upload.wikimedia.org
People with a higher body mass do seem more attractive to mosquitoes and midges, as they emit more CO2, the article says.
Blood type
The results of a number of studies have shown that mosquitoes prefer blood type 0(I). The authors of the work, published in the Journal of Medical Entomology, found that one species of mosquitoes prefers to feed on blood type I compared to others, but a significant difference was observed only between groups 0(I) and A(II).
Recall that the AB0 system— a method of dividing blood into four groups by antigens – was introduced by the Austrian doctor Karl Landsteiner in 1901. 0(I) — the first — the most common blood group; A(II) — the second; B(III) — the third; AB(IV) — the fourth — the rarest.
The second group doesn't seem the most delicious to mosquitoes. Image: www.trulynolen.ca
Other studies have also confirmed that people with blood type A are less attractive to mosquitoes. And people with blood type A are hunted by almost twice as many blood-sucking insects. Fortunately, people with blood type A are much less likely to get severe malaria, which is carried by mosquitoes.
While some studies confirm the existence of a certain correlation between blood type and mosquito preferences, it is worth considering the limitations of these studies, experts note.
Temperature
It is believed that mosquitoes are more likely to land on people whose body temperature is higher than others, regardless of the reason. This conclusion was reached in the early 20th century by Frank Milburn Howlett, a British scientist working in India, when he noticed that mosquitoes always hovered around a hot teapot during tea drinking. As an experiment, he filled a gauze bag with insects and placed it next to a test tube of hot water.
When the steam from the test tube reached the insects, they were “attracted” to the side of the sac that was closer to the hot air. Howlett also noted that mosquitoes probably do not drink the blood of cold-blooded animals. Since then, many scientific studies have shown that mosquitoes do rely on heat and the carbon dioxide we exhale, but temperature is not so clear-cut.
Mosquitoes choose warmer “food”. Image: scx2.b-cdn.net
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Temperature itself is one of the most important factors affecting the life of insects. High temperatures, for example, can have a detrimental effect on their physiology, which is why many insect species have developed various strategies to avoid “overheating.” So, they may seek fresher habitat or regulate water loss, but even such hematophagous mosquitoes face the problem of heat stress with every «meal».
To understand, in To what extent mosquitoes are exposed to heat stress while feeding, the authors of a study published in the journal Current Biology found thatmosquitoes can lower their body temperaturewhile feeding.
This mechanism probably protects the insect itself, as well as the microorganisms living in it, from overheating. It turns out that mosquitoes really do choose warmer “food”, as a result of which they cool down.
Bacteria on the skin
Another interesting reason why you may be the one who attracts mosquitoes is the millions of bacteria that cover your skin. Yes, human skin is home to vital bacteria (microbiota), which probably influence the choice of blood-sucking insects. For example, a study published in the journal Plos One examined a species of mosquito called Anopheles gambiae, which carries malaria.
The authors of the article found that people with a large number of bacteria on their legs were very attractive to mosquitoes. At the same time, subjects with a higher microbial diversity seemed less attractive to mosquitoes.
Bacteria on human skin may attract mosquitoes. Image: i.natgeofe.com
The microbiome on your skin is influenced by your genetics, age and immune system, which we can't really do anything about. But the products you use to cleanse and moisturise your skin can also have an impact, so it may be worth avoiding antibacterial soaps if you want to protect yourself from insect bites, the authors of the article write.
Beneficial microbes also influence the chemicals we secrete. For example, human sweat itself is odorless until bacteria take hold of it, converting the compounds in sweat and sebum into volatile compounds, some of which attract mosquitoes, while others repel them.
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Who doesn't get bitten by mosquitoes?
As you can see, there are many reasons why mosquitoes bite you (or bite you less than others), but there is still much to be learned about mosquito preferences. Some researchers believe that there are even genetic predispositions to attract mosquitoes, but which ones are still unknown. Moreover, according to one interesting theory, mosquitoes actually bite everyone, some people just don’t notice the bites because they don’t react to them. And indeed, if your skin doesn’t itch or swell, it doesn’t mean you haven’t been bitten.
A mosquito can bite anyone, but the reaction may vary. This partly depends on the type of bite, the type of mosquito, our immune system, and also on our behavior — whether we brush the insect away or ignore it, — experts say.
But even if you are a real magnet for mosquitoes, you should not resign yourself to your fate, because there are effective measures to protect yourself from insects. Thus, experts recommend wearing light-colored clothes, since dark colors attract mosquitoes, while orange and yellow, on the contrary, repel them.
Mosquitoes carry many dangerous diseases. Image: hysses.com
You should also not neglect insect repellents that are applied to the skin, but alcoholic beverages, especially beer, should be avoided – the results of one small study showed that people who drank beer were much more attractive to mosquitoes.
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You should also pay attention to plants such as basil, lavender, lemon thyme and marigolds – mosquitoes, as a rule, do not like to appear near them. Well, if all the above tips do not help, try to stay close to people that mosquitoes like – this way you will definitely be bitten less.