DNA detective work on honey has given a rare insight into the foraging habits of honeybees.
Scientists used genetic tools to discover which plants the pollinators visited in the countryside.
They compared this with a study from 1952, finding big shifts in the wildflowers available to bees.
In the 1950s, honeybees mainly gathered pollen and nectar from white clover. Today, there is not so much of this plant about, so they seek alternatives.
These include oilseed rape and Himalayan balsam.
And there are fears that honeybees and other vital pollinators are running out of food supplies as wildflowers disappear in hedgerows and fields.
“We’ve seen these major changes in the UK landscape and the honeybees have shown us that from their honey samples,” Dr Natasha de Vere, head of conservation and research at the National Botanic Garden of Wales, told BBC News.
She said the agricultural systems of today didn’t have enough nectar for pollinators, with much of the habitat for bees being grasslands, which are a “kind of green desert”.
“There’s nothing that really flowers within those pastures anymore, whereas in the 1950s, those pastures would have been full of white clover and other wildflowers as well.”
To come up with their findings, the researchers analysed hundreds of honey samples sent in by beekeepers up and down the country, following an appeal on the BBC TV programme Gardeners’ World.
These were analysed by DNA barcoding, where