That irresistible scent: mosquito attraction to human odor in the absence of carbon dioxide

Mosquitoes that feed on humans transmit deadly diseases that affect hundreds of millions of people every year. Host-seeking females use a combination of carbon dioxide and skin odor cues to find human hosts. Even though whole skin odor is attractive by itself, specific compounds have not been identified that are attractive in the absence of a CO₂ plume. We use electrophysiology assays to identify a specific olfactory receptor neuron (ORN) class that responds to whole skin odor. From the human odor blend, we identify specific compounds that activate this ORN strongly. This response is conserved in both Aedes aegypti and Anopheles gambiae, even though these two species, both of major public health importance, are not closely related. We specifically suppress the activity of this ORN for hours by treatment with a reactive compound that is structurally related to known ligands. After treatment, mosquitoes show deficits in navigation toward human skin odor in a wind tunnel. This is among the first ORN classes shown to play a role in attraction to skin odor. The receptors expressed in this ORN are highly conserved, offering hope that compounds that affect their activity can be used in a new generation of economical and environmentally friendly lures and repellents for mosquito control.