Though falling bee numbers may seem a good thing to most people, thehard-working creatures carry out a myriad of important ecological tasks,writes Andrew Read.
Bees pollinate our crops, our native fauna - and our garden plants. Yet they are in decline in Ireland. Researchers have just been awarded funding to investigate.
"Pollinators provide an important ecosystem service for many of our agricultural crops. Apples and oilseed rape, for example, don't get pollinated unless bees are around to do it," says Dr Mark Brown. Last year he conducted a survey of bees in the Dublin area. "I'm really worried about the state of things," he says.
Some 71 species of solitary bees have been recorded in Ireland, and 20 species of bumblebees, according to Brown. "I've no idea if that number is still present," he says. In North America and some areas of Europe, bees are in decline, and some species have become extinct. "The UK has lost at least one species of bumblebee in the last 70 years," says Brown.
"In Ireland, species that used to be found all over are now restricted to the west, around Co Clare," he says.
Dr John Breen of the University of Limerick agrees. "There are certain species I'd have been familiar with across the whole of rural Ireland in the 1970s that are now much rarer. I think the diversity of bees is going down a lot."
"But we don't have good background data," says Brown. He is working to rectify that. He and Dr Robert Paxton at Queen's University Belfast have just been awarded a €283,000 grant to look into Irish bees. It is funded by the Higher Education Authority North South Programme for Collaborative Research Strand 1, one of a range of initiatives intended to increase cross-Border initiatives.
Brown's work in the Dublin area last year, funded by the Heritage Council, generated the first quantitative data for any bee species anywhere in Ireland, he says. "There are records of 16 species of bumblebee in the area, but despite sampling 1,100 bees over the whole season, we found only eight species, and of those, only four were common," he says.
The causes of the decline are hard to pinpoint, but are likely to involve changes in land use. "The increasing urbanisation around Dublin, the elimination of green space and especially rough ground are probably involved," says Brown.
"Habitats are disappearing more in the east than the west," says Breen.
"I imagine this must be having an impact on annual self-seeders like apple trees, where the plant needs to be pollinated," says Brown. "It must also be affecting plant biodiversity in urban areas, but there are no quantitative data," says Brown.
"It's a chicken-and-egg situation," says Breen. "If the plants disappear, so will the bees, and so the plants and so on."
Brown is planning survey work to collate data on bee abundance and distribution to combine it with data on land-use, rainfall and plant cover. "We want to say what's important for those species. We want to identify areas that are highly diverse.
"For certain species we might need to preserve a particular site, but for the majority of species, they can be managed with set-aside and controlling mowing and grazing regimes. This should be feasible in the context of the Common Agricultural Policy," he says. "But until we know what the animals need, we can't make any recommendations at all." In Ireland, there are no protected insect species except the marsh fritillary, he notes.
One outcome of the work might be the discovery of new species.
Together with Breen and Dr Andrew Bourke at the Institute of Zoology in London, Brown is using genetic techniques to determine whether a bee species found on the Aran Islands is a species unique to Ireland.
He and Paxton also want to know about the genetic status of the bees. "Are the rare species lacking genetic variability? That will impact on their evolutionary trajectory. Are they suffering higher levels of inbreeding depression?" he asks.
The importance of bumblebees is such that importing them is now a booming business, says Paxton. "Ninety-nine out of 100 tomatoes in supermarkets have been pollinated by bumblebees," he says.
There are about 80 strawberry and tomato growers in the Republic, all of whom are importing bumblebees for pollination, says Dermot Roughneen of Teagasc, the agricultural research and advisory authority.
"Importing bumblebees is big business," he suggests.
"We've sent 800 colonies into the Republic so far this year," says Daniel Flory from Koppert UK, one of the companies that exports bumblebees to Ireland from the Low Countries.
But Paxton cautions, "We don't know if the diseases of imported bees are specific to those bees, or whether they will affect the indigenous species."
Andrew Read is a research scientist at the University of Edinburgh and a British Association for the Advancement of Science Media Fellow on placement at The Irish Times.