Devastating diseases are killing off vast numbers of bees across the country, threatening major ecological and economic problems. Honeybee colonies have been wiped out this winter at twice the usual rate or worse in some areas.

Honeybee colonies in Britain have been wiped out this winter
Honeybees account for 80pc of all pollination

The losses are the result of either Colony Collapse Disorder (CCD), a disease that has already decimated bee populations in the US and parts of Europe, or a new, resistant form of Varroa destructor, a parasite that attacks bees.

Experts fear that, because honeybees are responsible for 80 per cent of all pollination as they collect nectar for the hive, there could be severe ecological problems with flowers, fruit and crops failing to grow.

The pollination carried out by bees is worth £200 million to Britain's farmers each year. However, the total contribution by bees to the economy, including profits made from the sales of food, is up to £1 billion.

In London, about 4,000 hives - two-thirds of the bee colonies in the capital - are estimated to have died this winter.

The normal winter mortality rate is about 15 per cent. John Chapple, the chairman of the London Beekeepers' Association, who has lost the populations in 30 of his 40 hives, said:"It's frightening. The mortality rate is the highest in living memory and no one seems to know what's behind it."

In 23 of Mr Chapple's hives, no trace was left of the bees - a characteristic commonly associated with CCD. Officers from the National Bee Unit at the Department for Environment, Food and Rural Affairs (Defra) in Sand Hutton, near York, are investigating the cause of the population slump.

They fear that, with many beekeepers yet to check their hives after the insects' winter quiescence - a form of hibernation - the extent of the problem may deepen. So far, almost 30 per cent of hives inspected by the unit have been lost, twice the normal winter loss rate.

In Worcestershire and Hereford, of the 20 hives checked, only one had survived. In West Sussex, more than 80 per cent of the colonies had been lost. In Cambridgeshire, the figure was more than 50 per cent.

A spokesman for Defra said:"It is too early in the year to reach any conclusions. Some individual beekeepers have experienced large losses, others none. Any beekeeper who has concerns should make contact with the local bee inspector."

However, a source at the unit said:"People are only just starting to check their colonies but we are already hearing of losses. We're concerned. We think the losses are going to be higher." The British honey production industry provides more than a fifth of annual honey sales - up to 6,000 tons and is worth between £10 million and £30 million. Last year, Britons consumed more than 34 million jars of honey, compared with 31 million the year before. A spokesman for Tesco, the supermarket chain, said it would monitor the situation.

Beekeepers fear that cuts in Defra's funding for bee research - from £250,000 in 2004 to £180,000 next year - have left them vulnerable. They plan to meet this month to discuss the new threats.

Tim Lovett, the chairman of the British Beekeepers' Association, said:"There's been an inexorable decrease in investment in beekeeping research. The work going on is pretty limited. All this green chat from the Government is about recycling but there is not half enough being done for something that actually has a serious role in the environment."

In the 1990s, the honeybee population was badly affected by Varroa destructor. As well as almost eradicating Britain's wild swarms, many bee-keepers were put out of business and membership of the BBKA halved from 16,000 in 1990 to 8,000 a decade later. Chemicals were eventually developed to treat the condition, leading to a revival in the number of hives.

Norman Carreck, a bee­scientist, said:"For 10 years we have been rather complacent and thought Varroa was easy to deal with. Suddenly we're finding it isn't as easy as we thought." In the US, 50 per cent of honeybee colonies have been destroyed by CCD, while hundreds of thousands have been wiped out in Spain.

Bee-keepers in Poland, Greece, Croatia, Switzerland, Italy and Portugal have also reported heavy losses. Meanwhile, scientists at universities in Southampton and Stirling who are concerned about declining numbers of wild bumblebees - which also aid pollination - are to use dogs to search for colonies in Scotland and Hertfordshire this year.