Surprisingly, only a small fraction of the more than 3,000 mosquito species are actually specialized in biting humans. Instead, most of them feed from a variety of different sources.
However, the Aedes and Anopheles mosquitoes are known for their preference for human blood and their role as intermediaries for disease transmission in humans. Aedes mosquitoes are associated with Zika and dengue fever, while Anopheles mosquitoes carry the parasites that cause malaria.
Some mosquito species not only show a strong preference for human blood, but they also seem to “discriminate” between individuals when choosing their meals.
Aedes and Anopheles mosquitoes are known for their preference for human blood.
Although this is just anecdotal, it has been supported by research. So why is this the case? What factors might influence mosquito blood preferences?
There are many explanations for this issue, but some seem more plausible than others.
Some people believe that blood type, having beautiful skin, sweating, and even consuming garlic or vinegar foods can influence mosquito biting rates in one way or another.
There are numerous anecdotes explaining this phenomenon, but they have little scientific backing.
Nevertheless, significant research efforts have been directed towards understanding mosquito biting preferences, primarily with the hope of controlling their behavior to manage human diseases.
Why Are You Bitten by Mosquitoes More Than Others?
However, it’s not that for these tiny “blood-sucking monsters“, one person’s blood tastes “better” than another’s. In a discussion at the 2014 TED conference (Technology, Entertainment, and Design) held in Vancouver, Canada, on March 19, microbiologist Rob Knight explained that bacteria or microbes on the skin produce different chemicals, some of which emit scents more attractive to mosquitoes.
Some people with thin skin or blood type O become preferred targets for mosquitoes.
All female mosquitoes need to feed on blood to nourish their eggs during reproduction. Some species will only feed on animals, while smaller species target humans. It is difficult to determine why mosquitoes can detect human blood and differentiate between specific scents. We only know that when searching for a meal, they will utilize a variety of special senses that function like a humidity and CO2 detector.
Mosquitoes can recognize up to 300 different chemicals that we emit into the air daily. With more than 3,000 different mosquito species, each has its inherent tendencies. For example, some species are quite aggressive, while others appear more docile. Some mosquitoes even specifically choose our legs as their location for “dinner.”
Previous studies indicate that most mosquito species prefer darkness, warm places, or areas with high CO2 concentrations. They are attracted to movement and alcohol vapors when we drink. Some people with thin skin or those with blood type O become preferred targets for mosquitoes. And notably, they are fond of sweat.
Billions of bacteria live on the skin, making up a tiny fraction of the total 100 billion bacteria residing on and within the human body. However, they play a crucial role in producing body odor. Without these bacteria, human sweat would not emit any scent.
Some people have more attractive scents to mosquitoes than others
However, the types of bacteria on one person are very different from those on another. Knight explained that while our DNA is 99.9% identical, most individuals share only about 10% of similar bacteria.
To illustrate how mosquitoes are attracted to certain types of bacteria on the skin, researchers asked 48 male volunteers to avoid alcohol, garlic, spicy foods, and to refrain from bathing for two days. These individuals wore pantyhose for 24 hours to collect a sample of unique skin bacteria.
Subsequently, the researchers used glass beads rubbed on the feet of the volunteers to capture the scent as bait for mosquitoes.
The result showed that 9 out of the 48 volunteers were particularly attractive to mosquitoes, while the scent of 7 other fortunate volunteers was completely ignored by mosquitoes. The “highly attractive to mosquitoes” group had a concentration of common skin bacteria that was 2.62 times higher; and the concentration of other common bacteria was 3.11 times higher compared to the “not attractive to mosquitoes” group. The less attractive group had a more diverse array of skin bacteria.
Some mosquito species prefer the scent of fresh sweat, while others favor the odors produced by long-term bacterial activity on the body. Overall, when you sweat and are not clean, you become a bigger target than ever for mosquitoes.
Researchers suggest that some people may have a natural scent that repels mosquitoes. However, there are still solutions for those with a natural attraction to mosquitoes, such as reducing beer consumption. People who drink beer are very attractive to these insects, according to researchers. But one thing they cannot change is their genetic makeup.
85% of the reason someone gets bitten by mosquitoes more relates to genetic traits.
It may sound unreasonable, but this is the result of multiple studies confirmed by scientists. 85% of the reason why someone is bitten more by mosquitoes relates to their genetic traits. The latest research on this was conducted and published in April by scientists from the London School of Hygiene and Tropical Medicine.
They selected 18 pairs of identical twins and 19 pairs of fraternal twins to participate in the study. This allows for standardization of conditions for the control groups, leaving only the possibility that attraction to mosquitoes comes from genetic factors.
The results were predictable. Jame Logan, the entomologist leading the study, stated, “Identical twin pairs have corresponding levels of mosquito attractiveness. However, this varies greatly among fraternal twin pairs. Therefore, the answer to whether someone is attractive or not to mosquitoes lies in genetics.”
Mosquitoes are the leading killers of humans.
This conclusion may steer all future research aimed at finding ways to prevent mosquito bites in a new direction. “If we understand how genes influence this, we can develop new mosquito repellents,” Logan said. This could provide a basis for addressing many terrible diseases for which mosquitoes are the leading killers of humans.
The best tool we have today for mosquito prevention is DEET, a compound developed by the military since 1952. However, unfortunately, it has been classified as a neurotoxin, albeit at a low level. Permethrin, an insecticide used to combat mosquito-borne diseases, is even worse. Recent reports have suggested it may pose a risk of cancer.
Therefore, research into why mosquitoes favor certain individuals is not merely to answer your simple curiosity. It represents an opportunity for us to overcome barriers in the fight against mosquito-borne diseases. After more than half a decade of using DEET and Permethrin, they have proven to be imperfect solutions. “The more we understand about what drives mosquito preferences, the more opportunities we have to design better strategies to protect the public,” concludes Richard Pollack, an entomologist and public health expert at Harvard University.
