America’s bees are in trouble. Since colony collapse disorder (CCD) hit the U.S. in 2006, the country’s beekeepers have reported an average annual hive loss of 30 percent, reports Modern Farmer.

CCD is not just a critical issue for bees, but for the agricultural system. One-third of America’s food depends on bees and the industry is responsible for $15 billion in increased crop value annually.

Honeybee breeders across the nation are looking to hardy, resilient bees they call “survivor stock” as an important step toward solving the problem of CCD. A host of factors likely play a role in CCD, including habitat loss, some use of agricultural chemicals and an array of pests and diseases.

While there is no standard definition for “survivor stock,” longevity and natural pest resistance are key, plus a variety of other characteristics. Commercial beekeepers and the growing number of so-called “hobby beekeepers” are working to find a solution to CCD.