Why Do Mosquitoes Bite Some People More Than Others?

The incessant buzz of mosquitoes is a sure way to ruin a warm summer evening. Some lucky individuals may escape unscathed, while others become an all-you-can-eat buffet. For those wondering what factors entice hungry female mosquitoes to selectively target someone, scientists have some evidence-driven ideas.

A combination of factors, such as carbon dioxide, heat, and skin odor entice mosquitoes. While general cues for warm-blooded animals are carbon dioxide and heat, mosquitoes use odors to distinguish between humans and animals. It turns out that mosquitoes strongly prefer human odors over animal odors.¹

Meg Younger, a neuroscientist at Boston University, noted that carbon dioxide sensitizes mosquitoes to the presence of other odors. “This difference in odor between people accounts for the difference between the attraction of mosquitoes to different people,” she said.

Decoding odor profiles and the corresponding behavioral preferences of mosquitoes is tricky.² “Human odor is composed of hundreds of different volatile chemical molecules that somehow signal the presence of a human,” explained Younger. An emerging theory postulates that the skin microbiome constitutes body odor. “Our skin is covered in bacteria that emit volatiles that vary from person to person.”

While scientists have scratched the surface of quantifying the blend of complex odors that guide mosquitoes, there is good evidence for other factors that entice mosquitoes: being hot and sweaty. Consumption of alcohol, pregnancy, and even malaria infections make a person more likely to be bitten due to increased emitted carbon dioxide and raised body temperatures.³

But don’t worry, mosquito magnets! Scientists hope to develop new repellants to camouflage these tantalizing scents so that pesky mosquitoes can bug off!

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Reference

1. Zhao Z, et al. Nature. 2022;605:706-712.
2. Giraldo D, et al. Current biology. 2023;33(12): 2367-2382.
3. Ellwanger JH, et al. Curr Res Parasitol Vector Borne Dis. 2021;1:100058.