Female mosquitoes, which can transmit deadly diseases like malaria and the West Nile Virus, are attracted to potential hosts by "smelling" the carbon dioxide they exhale, according to a recent study.
Carbon dioxide draws in the blood-sucking insects, making them capable of tracking people from a distance. However, once they get close to their host, they are drawn to skin odors and steer away toward exposed areas such as ankles and feet, according to recent research.
Scientists at the University of California, Riverside said the receptors in the mosquitoes maxillary palp that detect carbon dioxide are ones that detect skin odors as well, which explains why mosquitoes are attracted to skin odor -- smelly socks, worn clothes, bedding -- even in the absence of CO2.
"It was a real surprise when we found that the mosquito's CO2 receptor neuron ... is an extremely sensitive detector of several skin odorants as well, and is, in fact, far more sensitive to some of these odor molecules as compared to CO2," Anandasankar Ray, an associate professor in the Department of Entomology and the project's principal investigator, said in a statement. "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."
Until now, it was a mystery which mosquito olfactory receptor neurons - which detect different odors - were required for attraction to skin odor, according to a press release.
The researcher's finding - that the CO2-sensitive olfactory neuron is also a sensitive detector of human skin - is apparently critical not only for understanding the basis of the mosquito's host attraction and host preference, but also because it identifies this dual receptor of CO2 and skin-odorants as a key target that could be useful to disrupt host-seeking behavior and thus aid in the control of disease transmission.
Researchers said this information can be used to create better mosquito traps.
"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," Ray said.
