BEIJING, April 17 (Xinhuanet) -- Studies have proven mobile phone usage does not cause brain cancer, but now some experts claim mobile phone radiation may be responsible for a drastic -- and so far unexplained -- decline in the number of honeybees.

    Beekeepers worldwide have reported increasing incidents of "Colony Collapse Disorder," a phenomenon normally evident between late summer and early spring as older bees die and hives fail because only the queen and worker bees too young to forage for pollen and nectar remain.

    The United States has been particularly hard-hit by CCD. Earlier this year 24 states reported  "heavy losses," and hives in Greece, Italy, Poland, Portugal, Spain, and the UK have also been affected.

    Experts have suggested harmful pesticides, increased solar radiation, falling queen fertility, and use of unauthorized bee treatments are possible causes of CCD. Now, German researchers at Landau university have found mobile phone signals can interfere with bees' "navigation systems".

    The scientists placed cordless-phone docking units that emit electromagnetic radiation into beehives. They discovered that "in some cases, 70 per cent of bees exposed to radiation failed to find their way back to the hive after searching for pollen and nectar," according to The Telegraph.

    "There is so much being said about CCD in America and [radiation] hasn't been mentioned. Until someone does a large study, it is hard to be sure," said Brian Dennis of the UK's Bee Improvement and Bee Breeding Association."

    (Agencies)