HAMPTON COURT PALACE, England -- First it was birds and now it is bees that are finding their numbers under increasing pressure from sources as diverse as habitat loss, insecticide use and changing weather patterns.

While many in the bird world are convinced that climate change is a major culprit for altering flowering times and therefore the relative abundance or lack of food sources, in the somewhat fustier apiarian world, the jury is out. Many, though, are willing to allow that climate change is likely to be a factor.

Honeybee colony losses have been 30 to 40 percent in the United Kingdom in the recent past and more than 60 percent in the United States.

The implications are not just potentially less honey. Bees are nature's top plant pollinators and are therefore economically as well as ecologically crucial.

Environmental campaign group Friends of the Earth has calculated that if all bees were wiped out in the United Kingdom -- not a likely event despite the multiple sources of attack -- it would cost the country £1.8 billion a year ($2.81 billion) to hand-pollinate food crops in their place. And that leaves out the value of the resulting biodiversity loss. Apply that calculation globally, and the picture is hair-raising.

Many blame neonicotinoid insecticides -- a new type of insecticide related to nicotine that attacks the nervous system of the insects and is deemed less toxic than organophosphates -- although not everyone agrees. Some scientists complain that experiments to date have been restricted to laboratories and do not replicate the real world.

The spotlight has also recently swung onto the varroa mite, which is omnipresent in honeybee colonies but seems to become a major threat when those bees have been weakened and made vulnerable by some other factor.

"Varroa is probably the single most important thing affecting honeybee populations. If you talk to French beekeepers, they will tell you that pesticides killed their bees. But it is pesticides and varroa. If you talk to the Spanish bee researchers, they will tell you that a gut parasite is killing their bees. But it is the gut parasite and varroa," said Norman Carreck, science director of the International Bee Research Association at the University of Sussex.

'The wrong weather at the wrong time'

But one fact that bee experts all agree on is that while bees, particularly honeybees, are very adaptable creatures in normal circumstances, they are highly vulnerable to extremes of weather, particularly downpours and flooding.

"Weather has a huge impact on honeybee survival. What seems to be happening is that we in the U.K. are getting more extremes of weather at either end of our normal range. Whether that is due to climate change is an interesting question," Tim Lovett, director of public affairs at the British Beekeepers' Association, said last month at the annual Hampton Court Flower Show about 10 miles southeast of central London.

"The wrong weather at the wrong time can be very bad for bees," he added. "One of the major causes of loss among honeybees in the spring is starvation. There are suddenly thousands of new mouths to feed. If they wake early and the plants are still asleep, then there is trouble. Likewise, if the plants wake early and the bees are still asleep and miss the first flush, then there can also be trouble."

Botanist Sandra Bell at the world-renowned Kew Gardens in London said flowering times have advanced by several weeks over the past half-century. While it is hard to pin that on climate change, it is certainly one of the effects to be expected, according to the models.

There are about 25,000 bee species globally. A U.N. Environment Programme report released last year notes that bees pollinate 70 percent of the world's top 100 staple food crops. It cites a combination of factors such as pesticides, insecticides and habitat loss for the dramatic declines in bee numbers around the globe.

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