WASHINGTON (AP) - A survey of beekeeper shows that winter hit U.S. honeybees hard with the highest loss rate yet.

  

The annual nationwide survey by the Bee Informed Partnership from several universities finds that nearly 38% of honeybee colonies died this past winter, about 9 percentage points higher than the average winter loss.

  

University of Maryland's Dennis vanEngelsdorp, president of the bee partnership and co-author of the survey, says beekeepers had been seeing fewer winter colony losses until now.

  

He calls Wednesday's results troubling.

  

Bees pollinate $15 billion worth of U.S. food crops. One-third of the human diet comes from pollinators.

  

For more than a decade, bees have been in trouble with scientists blaming mites, diseases, pesticides and loss of food.