BELTSVILLE, Md. -- Unless someone or something stops it soon, the mysterious killer that is wiping out many of the nation's honeybees could have a devastating effect on America's dinner plate.Honeybees don't just make honey; they pollinate more than 90 of the tastiest flowering crops Americans have.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.About one-third of the human diet comes from insect-pollinated plants, and the honeybee is responsible for 80% of that pollination, says the U.S. Department of Agriculture.Even cattle, which feed on alfalfa, depend on bees. So if the collapse worsens, people could end up being "stuck with grains and water," said Kevin Hackett, national program leader for the USDA bee and pollination program. "This is the biggest general threat to our food supply."While not all scientists foresee a food crisis, noting that large-scale bee die-offs have happened before, this one seems particularly alarming.U.S. beekeepers in recent months have lost one-quarter of their colonies -- about five times the normal winter losses -- because of Colony Collapse Disorder.The problem started in November and seems to have spread to 27 states, with similar collapses reported in Brazil, Canada and parts of Europe.Scientists are struggling to figure out what is killing the honeybees, and early results of a study this week point to some kind of disease or parasite.Even before this disorder struck, U.S. honeybees were in trouble. Their numbers were steadily shrinking, because their genes do not equip them to fight poisons and disease well and because their gregarious nature exposes them to ailments afflicting thousands of their close cousins."Quite frankly, the question is whether the bees can weather this perfect storm," Hackett said. "Do they have the resilience to bounce back? We'll know probably by the end of the summer."Experts from Brazil and Europe have joined in the detective work at the USDA's bee lab in suburban Washington."This crisis threatens to wipe out production of crops dependent on bees for pollination," Agriculture Secretary Mike Johanns said.

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