CNN Update on Honeybee die-off

Scientists are struggling to figure out what is killing the honeybees, and early results of a key study this week point to some kind of disease or parasite.

BELTSVILLE, Maryland (AP) -- Unless someone or something stops it soon, the mysterious killer that is wiping out many of America's honeybees could have a devastating effect on the country's dinner plate, perhaps even reducing its people to a glorified bread-and-water diet.

Honeybees do not just make honey; they pollinate more than 90 of the tastiest flowering crops the country has.

Among them: apples, nuts, avocados, soybeans, asparagus, broccoli, celery, squash and cucumbers. And lots of the really sweet and tart stuff, too, including citrus fruit, peaches, kiwi, cherries, blueberries, cranberries, strawberries, cantaloupe and other melons.

In fact, about one-third of the human diet comes from insect-pollinated plants, and the honeybee is responsible for 80 percent of that pollination, according to the U.S. Department of Agriculture.

Even cattle, which feed on alfalfa, depend on bees. So if the collapse worsens, Americans could end up being "stuck with grains and water," said Kevin Hackett, the national program leader for USDA's bee and pollination program.

"This is the biggest general threat to our food supply," Hackett said.

While not all scientists foresee a food crisis, noting that large-scale bee die-offs have happened before, this one seems particularly baffling and alarming.

U.S. beekeepers in the past few months have lost one-quarter of their colonies -- or about five times the normal winter losses -- because of what scientists have dubbed Colony Collapse Disorder.

A quick experiment with some of the devastated hives makes pesticides seem less likely. In the recent experiment, Pettis and colleagues irradiated some hard-hit hives and reintroduced new bee colonies. More bees thrived in the irradiated hives than in the non-irradiated ones, pointing toward some kind of disease or parasite that was killed by radiation.