The Plight of the Bumble Bee Affecting Plants Too
28 July 2006
Wild bees and the flowers they pollinate are disappearing together in Britain and the Netherlands, researchers have announced.
It is not clear which started to disappear first, the bees or the flowers, but the trend could affect both crops and wild species, the researchers report in a recent issue of the journal Science.
"We were shocked by decline in plants as well as bees. If this pattern is replicated elsewhere, the 'pollinator services' we take for granted could be at risk," Dr. Koos Biesmeijer of the University of Leeds in Britain said in a statement.
"And with it the future for the plants we enjoy in our countryside."
Biesmeijer and colleagues looked at species surveys from hundreds of sites and found that bee diversity has fallen in 80 percent of them since 1980. They said many bee species are declining or have become extinct in Britain.
The number of different species of pollination-dependent wildflowers has declined by 70 percent.
"In Britain, pollinator species that were relatively rare in the past have tended to become rarer still, while the commoner species have become even more plentiful. Even in insects, the rich get richer and the poor get poorer," said Stuart Roberts of the University of Reading, who worked on the study.
"We looked at plant changes as an afterthought, and were surprised to see how strong the trends were," added Bill Kunin of the University of Leeds. "When we contacted our Dutch colleagues, we found out that they had begun spotting similar shifts in their wildflowers as well."
Field scabious © Malcolm Storey 2001
Field scabious (Knautia arvensis) provides pollen
and nectar to a wide range of insects. The
scabious bee, Andrena hattorfiana, raises her
young exclusively on pollen from this plant.
Studies show that both species have recently
declined in Britain and the Netherlands. Field
scabious is still common, but much less so than
several decades ago. In addition, grazing and
early cutting of hay meadows makes that field
scabious often does not reaches the flowering
stage. This may be a major cause of the
decline of the scabious bee.
The absence of the bee may also play a role in
the decline of the plant. The bee has been
shown, in a Swedish study, to be a more
effective pollinator of field scabious than other
bees and hoverfly visitors. The good news is
that adequate habitat management can help
the declining bee and its food plant.
Pollinators are essential for the reproduction of many wild flowers and crops. Co-author Simon Potts (of the University of Reading) said: “The economic value of pollination worldwide is thought to be between £20 and 50 billion each year.”
In Britain, where bee diversity has fallen and hoverflies have at best held steady, there have been declines in 70% of the wildflowers that require insects for pollination. However, wind-pollinated or self-pollinating plants have held constant or increased.
The research can’t tell us whether the bee declines are causing the plant declines, or vice versa, or indeed whether the two are locked in a vicious cycle in which each is affecting the other. It’s also not clear as of yet what the ultimate causes of the declines are, although land use change, agricultural chemicals and climate change may be important factors. The researchers hope to clarify these issues with follow-up studies.
Meanwhile in Scotland, a sniffer dog has been hired in a bid to save endangered bumblebees from extinction. For the next five weeks, Quinn, a specially trained springer spaniel, will roam the remote terrain of the Outer Hebrides, tracking down colonies of the insects.
The project has been launched by the Bumblebee Conservation Trust.
The group want to find out how many rare bumblebees are left in the UK and what can be done to protect them. Quinn, a former stray, was trained at the Defence Animal Centre in Melton Mowbray, Leicestershire.
But while most of his canine colleagues have been taught to hunt for drugs and explosives, cop dog Quinn has been taught to nose out bee nests.
He will be guided by his handler Joe Waters, a student at Southampton University who is investigating the ecology of bumblebees. He said Quinn's training had involved acquainting him with the smell of an old bumblebee nest before hiding it and getting him to retrieve it.
He said: "The main aim is to discover bumblebee nest density for the whole range of species on the island and compare this with the diversity of habitats at present."
In the US, bees are responsible for pollinating up to one-third of the food supply, yet they have been dying off in alarming numbers for almost two decades. Faced with such detrimental foes as parasitic mites, pesticides, and urban development, bees are at a formidable disadvantage in our modern world. But since crops are so dependent on the work of these tiny creatures, beekeeping has become a big business, and maintaining effective hives is practically a competitive sport. Honeybees, even as they dwindle in number, are the most dependable source of pollination, carrying much of the burden to sustain our agricultural needs.
John Keeley is a retired civil engineer who keeps bees to pollinate his orchards: cherries, apples, peaches, plums and chestnuts. “You can easily double your fruit-tree production just with bees,” he says. But this winter, he lost 12 of his 14 honey-bee hives. “In February, they seemed to be doing all right,” he says. “By March, they were all dead.”
He picks up a hive frame still thick with honey along the edges and gently puts his thumb and forefinger around a dead bee, curled stiff against the honeycomb. “See, they had plenty of honey to eat,” he says. “I don’t know what killed them.”
Like most beekeepers these days, Keeley doses his hives with a variety of treatments to keep the bees free of affliction: disease, mites and invasions by marauding animals such as skunks. But honey-bee populations are plummeting nevertheless. “We’re losing between 40 and 60 percent of our bee population annually in this country,” says Gordon Wardell, an entomologist based in Tucson. “The bee industry is right on the edge.”
Honey bees pollinate more than 90 cultivated crops, including avocadoes, cucumbers, watermelons, citrus fruit and, notably, almonds; California’s almond industry alone needs about half the country’s 2.5 million commercial hives for pollination every year. Honey bees are responsible for more than $20 billion in annual pollination value and one-third of the food we eat, from vegetables to oils to meat from animals that graze on pollinated forage.
Managed honey bees, such as Keeley’s, aren’t the only pollinators in the air. According to Michael Burgett, an entomologist based in Corvallis, Oregon, in the Pacific Northwest alone there are some 900 species of native bees. And plenty of plants, such as tomatoes, get along fine with mere wind pollination. But because modern agriculture demands high yields from densely planted crops, they need modern commercial honey bees, in massive quantities, in order to seize the day when the bloom is peaking.
Meanwhile, Antigua is in the middle of a significant honey production shortage that is expected to last for at least four years.
The problem is due to the Varroa or vampire mite that came to Antigua’s shores in the first quarter of last year.
Varroa mites are parasitic mites that feed off the bodily fluids of adult, pupal and larval bees. They can be seen with the naked eye as a small red or brown spot on the bee’s thorax and is a carrier for a virus that is particularly damaging to the bees.
Dr. Anthony Richards, chief government chemist and member of the Antigua Beekeepers Cooperative, said that the mite was discovered on Rat Island, through a regular surveillance for Africanised bees or "killer bees'.
It was estimated that the infected bees came in at Deep Water Harbour in a shipment of construction pipes. The parasite is said to have infected most areas of the world now and is consequently affecting honey production.
In the last year the bees have completely taken over Antigua while Barbuda is safe for the moment. Chief Extension Officer Sereno Benjamin described the situation as a massive problem that is very troubling.
One bee farmer, Kathy Knight, has estimated that by next year Antigua will have a shortage because the bees are just disappearing.
But Benjamin said that a shortage is already here. He related that when the agricultural department had wanted honey to be displayed at the Anglican food fair and to give to boat crews during the Antigua Sailing Week, there was a problem securing enough.
Prior to the Varroa mite problem, Antigua had an estimated 350 to 400 bee hives. That population is estimated to be severely depleted. Richards estimated that only about 20% of his stock has survived the parasites. About 50% to 80% is the usual rate of population destruction.
President of the Antigua Beekeepers Cooperative Alvin Langlais said that usually around this time of the year, the Cooperative usually has 5 barrels of honey in excess. Now they cannot find enough to fill their orders.
Many groups will be affected by the decimation of the honey bee population. Knight expects that the farmers will feel the shortage because the bees will not be there to pollinate their crop. “At one time there were no bees in our yard at Parham and after I brought in the bees we started to get a lot of sugar apples, a lot of citrus fruits just because of the bees pollinating the trees.”
Langlais agreed. He said that at present producers of melons and cucumbers have reported a significant decrease in their crop yields.
Hotels, supermarkets and restaurants are also expected to suffer because the Cooperative will be unable to fulfil their production expectations.
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