But it also says changed weather patterns -- possibly due to climate change -- are altering flowering times as well as causing droughts and floods.
The United Kingdom has about 250 species of bees, of which one is the honeybee, 25 are bumblebees and the remainder are so-called solitary bees, which, because they do not provide honey and are not as picturesque as the hairy bumblebees, are mostly under the research radar. But they all pollinate.
Debating the role of climate change
While the honeybee, whose hived colonies are managed and fed sugar water when the necessary nectar is absent, is adaptable enough and managed enough to survive despite significant losses, the same is by no means true of all the other bees.
And according to Gill Perkins, conservation manager at the Bumblebee Conservation Trust, while honeybees used to be the most numerous and therefore the most important plant pollinators, that is no longer the case.
She doesn't blame climate change. She blames intensive agriculture, noting the disappearance since World War II of 97 percent of the United Kingdom's wildflower meadows, which provided the mainstay of the bees' diet.
A report earlier this year from Reading University agrees with her lament at the loss of the country's former hay meadows but does not dismiss the impact of climate change.
"Climate change has had a notable impact upon the distribution of many wild bees, with several species such as the newly-arrived Tree Bumblebee migrating north in the past 20 years as the climate has started to warm," says the report, titled "The Decline of England's Bees."
"Climate change can also disrupt the timing of plant flowering or bee emergence, resulting in wild bees emerging before or after ample forage is available," it adds.
For the University of Sussex's Carreck, the fact that so little is known about the detailed implications of climate change for species that are seemingly ubiquitous and vital, but are nonetheless under attack, is an oversight that needs to be corrected.
"Solitary bees are often only around for a very short period in the year, and some of them are associated with particular plant species. So if, due to climate change, the plant flowers at a different time of year than it normally does, but the bee comes out at the same time as it normally does, and the two don't coincide, then clearly you have got a problem for both the plant and the bee," he said.
"We should give just as much attention to the common species which control major ecosystems. If a very common species declines by 50 percent, it is still very common. But it could be having a dramatic effect on some major ecosystem," he added. "So you need to consider both the very rare species and the common ones at the same time. We often neglect the very common things because they remain common, and we don't notice that they are considerably less common than they used to be."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500