Read our COVID-19 research and news.

Aaron Joel Santos/Aurora Photos

Ghost peppers are saving U.S. grasslands—by scaring off hungry mice

Conservationists trying to restore the United States’s grasslands kept running into a problem: As soon as they planted the seeds meant to bring back native flora, hungry mice would gobble them up. In an effort to deter the rodents, biologists tried coating the seeds with capsaicin, the active ingredient that gives chili peppers their signature fiery taste. It worked: Dusting the seeds with chili powder reduced the number of seeds consumed by deer mice by 86%, researchers report in Restoration Ecology.

The hot discovery required some trial and error. One big challenge was finding a chili powder that would deter the mice but not prevent the seeds from germinating. Another was finding a coating that wouldn’t weather away after a few months outdoors. After 4 years of laboratory and field experiments in Montana’s Missoula Valley, researchers found a workable recipe. A powder made from the Bhut jolokia, or ghost pepper, from India—considered to be one of the world’s hottest chilis—did the trick.

The scientists suggest their findings demonstrate how natural plant defense compounds—such as capsaicin—can be used to aid restoration efforts.

*Correction, 8 August, 10:50 a.m.: The story described capsaicin as nontoxic. It is not. The story has been corrected.