Commercial beekeepers in the US lost one third of their honey bee colonies last winter, according to a survey conducted by the US Agricultural Research Service (ARS).
It is the fourth consecutive year of heavy losses for beekeepers, who reported a 29 per cent loss in 2008/9, 35.8 per cent in 2007/8 and 32 per cent in 2006/7.
In total, just over 60 per cent of beekeepers reported losses in excess of what they consider acceptable, which is generally a loss of around 14 per cent.
Colony collapse unlikely
The losses have previously been blamed on a phenomenon known as colony collapse disorder (CCD), where bees disappear from the hive leaving it with no or few adult honey bees, but still a live queen. No dead bees are found in the hive which has made it difficult so far for researchers to discover more about the causes of the collapse.
In this latest survey, researchers said it was not possible to identify via the interview-based survey whether the losses were cases of CCD.
Of the 4,000 beekeepers who responded to the online survey - representing around 20 per cent of the country's estimated 2.46 million colonies - only 5 per cent though that CCD was the major cause of their losses.
Instead, they blamed the losses on starvation (32 per cent), weather (29 per cent), weak colonies in the fall (14 per cent), parasitic mites and poor queens (10 per cent).
Francis Ratniek, the UK's only Professor of apiculture, said the main honey bee regions in the US had experienced very poor weather during the winter, which may explain the high numbers of losses attributed to starvation as bees are unable to go out and forage for food.
He said the continued heavy losses were likely to lead to rises in the cost of pollination services. In future, said Ratniek, only a few high-value crops, such as the California almond crop, may be able to afford to use commercial beekeepers to pollinate their crops.
Results from a survey of British honey bee colonies is expected later this month.
Information on colony collapse disorder
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