One summer evening, just raising a glass is enough to see an unwelcome guest appear: the mosquito. Yet some of us seem to attract these insects much more often than our neighbors.
A Dutch team recently explored this difference in mosquito appeal by transporting thousands of these small insects to a music festival. The goal: to observe which human behaviors influence their choice and why some people become real bite magnets.
A real-world experiment
Researchers from Radboud University set up a mobile laboratory in shipping containers at the Lowlands festival site in 2023. Nearly 500 volunteers agreed to participate. Festival-goers filled out a questionnaire about their habits, then placed their arm in a special cage containing female
Anopheles stephensi mosquitoes.
The mosquitoes could detect skin odors without biting thanks to fine perforations. A camera recorded the number of insects attracted to each participant. The researchers then compared these results with the collected data.
The results revealed a striking fact: people who had consumed beer in the previous twelve hours attracted 35% more mosquitoes. Wine did not show a similar effect, indicating a particular link between beer and insect attraction.
Multiple factors highlighted
Beer wasn't the only factor correlated with mosquito interest. Individuals who had shared their bed the previous night also seemed more sought after. In contrast, a recent shower or applying sunscreen significantly reduced attractiveness.
Skin analyses revealed an increased abundance of certain bacteria, particularly streptococci, in highly attractive individuals. These microorganisms could enhance the body odors that guide insects.
Cannabis consumption showed a more modest association, but this disappeared when other parameters were taken into account. As for blood type, it played no role in the experiment, confirming other previous work.
Why does beer make you more attractive to mosquitoes?
Scientists propose several explanations. Alcohol consumption can increase body heat by dilating blood vessels. It could also alter skin odors perceived by mosquitoes. However, this doesn't explain why wine doesn't have the same effect.
These insects first detect the carbon dioxide we exhale. They follow this invisible cloud to its source, before orienting themselves toward body heat and chemical signals from the skin.
Once close, mosquitoes evaluate the composition of sweat and products from the skin microbiome. These combined signals determine the precise location where they will bite.
Article author: Cédric DEPOND