DENVER -- Researchers in Germany may have found the cause of disappearing honeybees -- a worldwide problem that has also hit Colorado beekeepers hard.

The researchers are trying to determine what causes the collapse of colonies -- called Colony Collapse Disorder. Beekeepers have found many of their bees disappearing and the hives collapsing.

One beekeeper from the San Luis Valley reported he started the winter with 6,000 beehives and emerged with only 1,000. Other Colorado beekeepers have reported similar losses.

A German study shows that radiation from cell phones can disrupt bees' navigation systems. That keeps the bees from returning to their hives.

In some cases, 70 percent of bees exposed to radiation failed to find their way back to the hive after searching for pollen and nectar, according to the research by Landau University of Koblenz. Link to study (in German).

According to the study, radiation from cell phones disorients the bees and destroys their ability to communicate.

"When bees are exposed to signals from cell phones, they can't find their way. They get no nutrition and consequently die," said Dr. George l. Carlo, chairman of the Safewireless Initiative.

Colony Collapse Disorder has affected beehives in 24 states, including Colorado. Losses of 50 to 90 percent of colonies have been recorded. The loss rate is 40 percent in some Colorado's 30,000 colonies. Beekeepers said that many of their bees never return to the hives and the hives dwindle and die.

Bee pollination is valued at roughly $15 billion annually in the U.S., according to a report about Colony Collapse Disorder prepared for Congress. There are more than 2 million commercial bee colonies nationwide.

With cell phones spanning the globe, the theory could have major implications on agriculture. But scientists aren't passing final judgment just yet. Other theories range from global warming, dry weather, pesticides and toxins.

Regardless of what's causing it, the epidemic could trigger a big rise in food prices for consumers since honeybees are used to pollinate a third of the country's agricultural crops.