Mosquitoes flee from DEET-based insect repellent because of their intense dislike for the smell of the chemical repellent and not because DEET jams their sense of smell, report researchers at the University of California, Davis.
Their groundbreaking findings were published in the Proceedings of the National Academy of Sciences (PNAS).
“We found that mosquitoes can smell DEET and they stay away from it,” said noted chemical ecologist Walter Leal, professor of entomology at UC Davis. “DEET doesn’t mask the smell of the host or jam the insect’s senses. Mosquitoes don’t like it because it smells bad to them.”
DEET, the common name for N,N-diethyl-3-methylbenzamide, is the most common active ingredient in insect repellents. Developed by scientists at the U.S. Department of Agriculture and patented by the U.S. Army in 1946, DEET is considered the “gold standard” of insect repellents. Worldwide, more than 200 million people use DEET to ward off vectorborne diseases.
But DEET’s mode of action or how it works has puzzled scientists for more than 50 years. Scientists long surmised that DEET masks the smell of the host, or jams or corrupts the insect’s senses, interfering with its ability to locate a host. Mosquitoes and other blood-feeding insects find their hosts by body heat, skin odors, carbon dioxide (breath), or visual stimuli. Females need a blood meal to develop their eggs.
Leal said previous findings of other scientists showed a “false positive” resulting from the experimental design.
Source: University of California, Davis, USA