Honeybees in the U.S. have developed widespread resistance to the antibiotic tetracycline, likely as a result of decades of exposure to preventive antibiotics in domesticated hives, a new study has found. In tests conducted on bees in several countries, scientists from Yale University say they identified eight tetracycline resistance genes in U.S. honeybees that were largely absent in bees found in places where the antibiotics are banned. In the U.S., the use of oxytetracycline — a compound similar to tetracycline — has been common since the 1950s to help prevent outbreaks of “foulbrood,” a bacterial disease that can devastate honeybee hives. “There’s a pattern here, where the U.S. has these genes and the other [countries] don’t,” said Nancy Moran, a lead author of the study published in the journal mBio. The authors warn that the treatment meant to prevent disease and strengthen honeybee hives in the U.S. may have actually weakened the bees’ ability to fight off other pathogens.