Volatile Odorants Confuse Mosquitoes

Brief exposure to a blend of odorant molecules can knock a mosquito’s CO₂-sensing neurons out of whack and interfere with the insect’s ability to find its next meal, according to a report (Nature, DOI: 10.1038/nature10081). Female blood-feeding mosquitoes use exhaled CO₂ as a sensory cue to find their victims. Compounds that interfere with this sensing system could be a way to reduce disease transmission by diverting mosquitoes. Anandasankar Ray of the University of California, Riverside, and colleagues found that exposure to 2,3-butanedione activates CO₂-sensing neurons in three mosquito species—Anopheles gambiae, A. aegypti, and Culex quinquefasciatus. In the cases of A. gambiae and A. aegypti, a one-second pulse is enough to reduce the insect’s response to CO₂ for more than five minutes. The researchers found that a cocktail of 2,3-butanedione, 1-hexanol, 1-butanal, and 1-pentanal was effective at even lower concentrations than 2,3-butanedione alone. In a greenhouse experiment in Kenya, exposure to the odor blend reduced the number of C. quinquefasciatus females that entered a hut and were caught in CO₂-baited traps.