American farmers face a make-or-break summer as the honeybee population struggles to recover from a mysterious killer that threatens to destroy crops and deplete the nation’s dinner plates.

Officials at the US Department of Agriculture (USDA) say that unless the species manages to shake off the shadow of Colony Collapse Disorder over the coming months, the public could find itself “stuck with grains and water” as fruit orchards and vegetable fields go unpollinated.

The phenomenon, which causes bees to desert their hives en masse and disappear to die, has wiped out a quarter of America's 2.5 million honeybee colonies, which typically contain about 30,000 bees each, in six months.

“This is the biggest general threat to our food supply,” Kevin Hackett, leader of the Department of Agriculture’s bee and pollination programme, said. “The question is whether the bees can weather this perfect storm. Do they have the resilience to bounce back? We’ll know probably by the end of the summer.”

The Government is being lobbied to provide urgent new f u n d i n g for research into the causes of CCD, also known as Marie Celeste Syndrome, which has also wreaked havoc in Brazil, Canada and parts of Europe. There have been anecdotal cases of die-offs in Britain, though there is disagreement over whether CCD is to blame.

Concerned by the implications – one third of the human diet comes from flowering crops, and honeybees are responsible for pollinating about 80 per cent of them – a House of Representatives subcommittee has held hearings and the office of the Vice-President, Dick Cheney, has been briefed.

Federal, state and private resources are being ploughed into studies, and task forces and working groups have been established to pool expertise. Scientists from Europe and Brazil have joined in a study led by the USDA’s bee research laboratory in Washington to step up the hunt for clues.

Significant losses are already being felt by honey producers. Officials fear that the bee population is now at a dangerous tipping point and crops worth $15 billion (£8 billion) – including alfalfa, which provides crucial fodder for the $4.5 billion dairy industry – are ultimately at risk of failure.

“If the bees do not recover, or their numbers don’t grow and they are in a weakened state, we could see a worst-case scenario, ” Jeff Pettis, the top bee scientist at the USDA, said.

James Doan, a beekeeper in New York, moves his bees around the country according to demand from farmers, who rent the hives so that crops such as watermelons, apples, strawberries, broccoli, almonds and cucumbers can be pollinated.

He lost 3,300 colonies – about 100 million bees, worth $200,000 – to CCD between September and March. “If we can’t get this problem under control in the next three or four months, if I go back into winter facing these kind of losses, I can’t continue. Our bankers will tell us, ‘Sorry, that’s it,’ ” he said.

With the problem now affecting 27 states, he said: “I’m getting calls by the hour from growers who can’t find bees. And no honeybees equals no fruit and veg.” Among the factors that have been studied are the Varroa mite, which has been found to afflict hives with fatal consequences. It is considered a “stress factor” that may make bees more susceptible to CCD, but not the sole culprit.

Max Watkins, research director of Vita, the world’s largest honeybee health company, and member of a scientific group on bee loss in Europe, said: “Scientists all over Europe are trying to find out the cause; if it’s not Varroa, what is it?” He added: “It will be sorted out eventually, but it’s going to put a lot people out of business.”

Sheri Brothers, farm manager at Island Grove Agricultural Products near Gainesville, Florida, said: “Growers are concerned for the future. Our pollination season is in February, so we’re in the middle of harvest and summer is when we watch the bee population ahead of next year’s season. We’ll be watching them real close.”

The buzz

— Theories on disappearing bees:

— Hive infestation by mites, amoeba and other pests

— Radiation from mobile telephone masts

— Poisoning from pesticides

— Global warming

— Contamination from genetically modified crops

— Harmful waves from power lines

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