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Why Do Mosquitoes Bite "Tasty" Humans?

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The mosquitoes are coming! The mosquitoes are coming! For many, summer means hot days and backyard barbecues. But with all that fun in the sun comes the menace of mosquitoes, along with the itchy calling cards they leave behind. So why do some people get more of this undesirable attention than others?  Research suggests mosquitoes actually have discriminating tastes when it comes to their victims, choosing based on characteristics like scent and blood type [1] [2].

The Buzz About The Bite — Why It Matters

Illustration by John Block

Beyond the nuisance factor, mosquitoes are animal public enemy number one to humankind, killing more people each year than any other species. Females mosquitoes are the culprits (males don’t even have the equipment to bite humans!), causing millions of mosquito-borne diseases every year with a disproportionately heavy effect on developing countries.

These femme fatales might actual be choosing "tastier" targets, which is why it seems like certain people are stuck with more of those pesky bites. The first scent that the mosquito identifies is CO2 (human breath), which it can detect as far as 50 feet away. Research suggests the unique combination of chemicals that make up an individual's breath may play a role in repelling or attracting mosquitoes [1].

Differences in secretions on the human skin (like the ammonia and lactic acid in sweat) can also play an important role attracting mosquitoes to their victims [4]. Everybody has a body odor, but some people are lucky enough to have a combination of skin secretions that help mask the compounds mosquitoes love [5]. This kind of natural insect repellent has a very slight scent that people don’t notice, but mosquitoes do.

The Best Bug Bait — The Answer/Debate

Research points to blood-type markers — chemicals produced by people with specific blood types — as a determining factor for how mosquitoes pick out a tasty (human) snack. Type O blood is both a hot commodity for blood banks and an especially popular attractant for Asian Tiger Mosquitoes [6]. Mosquitoes also seem to like getting wasted. Drinking around a liter of beer has been shown to increase mosquito appeal by up to 15 percent, likely because skin odor may change ever so slightly when metabolizing a cold one [7].

For those especially high up on the mosquito menu, the real key to preventing bites is reducing exposure to the insects. This might seem especially difficult given the record numbers expected this summer, but there some easy fixes: Mosquitoes are less-than-picky about their habitats (what other insect chooses to brave the Arctic Circle?), so to reduce mosquito breeding areas around the home, remove any outside containers that can hold standing water (especially old tires), repair leaky outdoor faucets, and change the water in bird baths and pet bowls at least twice per week.

Even for the most stealth swatters, a good insect repellant can also make the difference for a less-itchy summer. DEET is the gold standard of repellants, but plant based options like soy, eucalyptus, and citronella can be effective natural options. Reducing time spent outdoors — especially in early morning and early evening hours when mosquitoes are most active — and wearing long pants and long-sleeved shirts can also help.

  • Mosquitoes have discerning tastes and will search out certain scents and blood types which are more attracting.
  • Mosquitoes are attracted to the CO2 in human breath and can detect it from 50 feet away.
  • Body odor can attract the pests but some people have a biological defense thanks to a combination of skin secretions.
  • Certain things attract mosquito populations such as standing water, types of blood (O is popular, for example), and drinking beer.
  • If braving the outdoors, make sure to stay covered and wear insect repellant when possible.

 

Originally posted July 2011. Updated May 2012.

Are you a mosquito magnet? How do you avoid the pesky pests during the summer?

 

Works Cited

  1. Allomonal effect of breath contributes to differential attractiveness of humans to the African malaria vector Anopheles gambiae. Mukabana, W.R., Takken, W., Killeen, G.F., et al. Department of Zoology, University of Nairobi,  Nairobi, Kenya. Malaria Journal. 2004 Jan 29;3(1):1.
  2. Landing preference of Aedes albopictus (Diptera: Culicidae) on human skin among ABO blood groups, secretors or nonsecretors, and ABH antigens. Shirai, Y., Funada, H., Seki, T., et al. Institute of Pest Control Technology, Ciel Foret, Murakami, Yachiyo, Chiba, Japan. Journal if Medical Entomology. 2004 Jul;41(4):796-9.
  3. Allomonal effect of breath contributes to differential attractiveness of humans to the African malaria vector Anopheles gambiae. Mukabana, W.R., Takken, W., Killeen, G.F., et al. Department of Zoology, University of Nairobi,  Nairobi, Kenya. Malaria Journal. 2004 Jan 29;3(1):1.
  4. Synergism between ammonia, lactic acid and carboxylic acids as kairomones in the host-seeking behaviour of the malaria mosquito Anopheles gambiae sensu stricto. Smallegange, R.C., Qiu, Y.T., Van Loon, J.J., et al. Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands. Chemical Senses. 2005 Feb;30(2):145-52.
  5. Interindividual variation in the attractiveness of human odours to the malaria mosquito Anopheles gambiae s. s. Qiu, Y.T., Smallegange, R.C., Van Loon, J.J., et al. Laboratory of Entomology, Wageningen University, Wageningen, the Netherlands. Medical and  Veterinary Entomology. 2006 Sep;20(3):280-7.
  6. Landing preference of Aedes albopictus (Diptera: Culicidae) on human skin among ABO blood groups, secretors or nonsecretors, and ABH antigens. Shirai, Y., Funada, H., Seki, T., et al. Institute of Pest Control Technology, Ciel Foret, Murakami, Yachiyo, Chiba, Japan. Journal if Medical Entomology. 2004 Jul;41(4):796-9.
  7. Beer consumption increases human attractiveness to malaria mosquitoes. Lefèvre, T., Gouagna, L.C., Dabiré, K.R., et al. Génétique et Evolution des Maladies Infectieuses, Montpellier, France. PLoS One. 2010 Mar 4;5(3):e9546.