Mosquitoes Hunt by Smell

Jan. 13, 2014, 4:25 p.m.

Research done by scientists from the University of California (UC) shows that mosquitoes were biologically engineered by Mother Nature to particularly target human beings and other mammals by smell.


Suckers for skin odor

The researchers’ work, which was recently published in science journal Cell, reveals that the same neurons that mosquitoes use to detect carbon dioxide, called cpA, are also receptive to the smell of human skin. This explains why mosquitoes always seem to find their way to humans, while specifically targeting the exposed parts of the body. In fact, the receptors are so sensitive to the smell of human skin that mosquitoes end up hanging around worn clothes, beddings, and even unwashed socks.

According to the project’s principal investigator, Anandasankar Ray, the results were surprising. “For many years we had primarily focused on the complex antennae of mosquitoes for our search for human-skin odor receptors, and ignored the simpler maxillary palp organs.”

The researchers were able to test cpA activation by shutting down the neuron in the dengue-carrying Aedes aegypti through the use of chemicals. Afterwards, they observed how mosquitoes with neutralized cpA activity reacted to a dish of beads scented with human foot odor, and found that the mosquitoes’ attraction towards the dish was greatly reduced.


Scent shields

Thankfully, the study has also revealed a number of compounds that wreak havoc on these pests’ internal human detector. Out of half a million screened compounds, the researchers identified 138 that could either inhibit or activate cpA. Additionally, a good majority (85%) of these have already been deemed fit for use in flavoring, fragrances, or cosmetic products. Some of these compounds are even pleasant-smelling flavors, such as raspberry, chocolate, and mint.

The researchers named two particularly effective compounds for mosquito control. Ethyl pyruvate, a fruity-scented flavor agent in food, was identified as a strong cpA inhibitor, while the mint-scented cyclopentanone, used in flavoring and perfume, proved to be just about as effective as CO2 in luring mosquitoes.


Safer, cheaper, and more pleasant methods of mosquito control

"Such compounds can play a significant role in the control of mosquito-borne diseases and open up very realistic possibilities of developing ways to use simple, natural, affordable and pleasant odors to prevent mosquitoes from finding humans," according to Ray, an associate professor in the Department of Entomology at the UC. “Odors that block this dual-receptor for CO2 and skin odor can be used as a way to mask us from mosquitoes. On the other hand, odors that can act as attractants can be used to lure mosquitoes away from us into traps."

CO2 is currently the primary compound found in mosquito traps. However, the process of generating CO2 necessitates a complicated, impractical, and heavily resource-consuming process. These new findings open possibilities for safer and inexpensive ways of developing mosquito traps or repellents that would work just as well as today’s CO2 traps. — TJD, GMA News

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