Wild honey bees: Does their disappearance matter?
New research suggests there may be no wild honey bees living in England or Wales, but how much does their disappearance matter?
Despite the current international concern at the health of managed honey bee stocks, the existence - and potential benefits - of wild native honey bees is often overlooked.
Wild colonies would be of the UK's native honey bee subspecies Apis mellifera mellifera, also known as the European dark bee, surviving on their own in remote areas or in a range of cavities.
It has been suggested that disease wiped them out in the early 20th Century, yet across most parts of the UK there remain anecdotal sightings of colonies thriving without human intervention.
The humble honey bee
And the fact that unmanaged bees have not been eliminated is of interest to those working to protect honey bees. But no empirical studies have been carried out to clarify the situation.
Dr Catherine Thompson, from the University of Leeds, set out to investigate the persistence, genetic diversity and disease burden of wild honey bees in England and Wales.
She identified three remote areas at least 6.2 miles (10 km) from any known apiaries (Tywi Forest in Wales, Ennerdale Forest, Cumbria and the Kielder Forest in Northumberland) and sampled them using bee traps, lures and observations. No wild honey bees were found.
The author concluded that there are unlikely to be any large, remote colonies of wild honey bees remaining in England and Wales and, as a result, she turned her attention to feral honey bees - colonies living in the wild that are thought to have escaped from managed stocks.
To discover their significance Dr Thompson asked bee keepers to report unmanaged colonies of bees that had lasted for at least a year near to them. She sampled bees from feral colonies along with those from managed colonies in the same area.
Genetic testing between the managed and feral colonies showed close similarities (2.5% difference) which she suggested meant that the feral colonies were likely to be swarms from managed colonies.
The managed colonies were further separated into those that were treated for the varroa mite and those that were not.
Varroa mites (Varroa destructor) entered the country in 1992, and are considered to be the most destructive parasite in honey bees and a major cause of winter colony loss.
Dr Thompson found that the feral and non-treated managed colonies had a significantly higher level of Deformed Wing Virus (DWV), which is transmitted to bees by the varroa mite, than the managed colonies that were treated.
By returning to the feral sites every spring and autumn for the next three years she found those colonies with high levels of disease were unlikely to survive.
The results of Dr Thompson's pathogen burden study are due to be published in the journal PLoS One.
"This study is important because it shows bee keepers that they are ultimately responsible for honey bees", Dr Thompson told BBC Nature. "If they stopped looking after their bees it is likely there would be no bees left.
"It is beekeepers' responsibility to maintain healthy and good quality bees which means continue with a programme of research into honey bee health, honey bee genetics and the health of the landscape in which we keep them."
Tim Lovett from the British Beekeepers Association said the research reiterated his organisation's founding principles.
"Dr Thompson has underlined the importance of beekeeping in monitoring bee populations and the responsibility of being a beekeeper; to make sure bees are kept healthy and well provided for," he said.
He added that more research was urgently needed into effective solutions to varroa mites.
But the Natural Beekeeping Trust, who promote treatment-free beekeeping, say honeybees are capable of developing disease tolerance themselves, as evidenced in many of their non-treated hives.
"These varroa tolerant bees have not been bred by anyone," the trust's Gareth John said. "They have gradually appeared over the 20 years since varroa arrived in the UK. From where? If not in beekeepers' hives, then in wild bee colonies. Albeit that those colonies may at first have been escapees, they cannot all have died out or we would not have the varroa tolerant bees we now see."
Norman Carreck, science director for the International Bee Research Association, believes all bees are wild.
"The work shows that bees living in trees and those living in hives are a cross population," he said. "Bees living in hives are essentially wild because bees mate on the wing so it is very difficult for beekeepers to control their mating."
He also suggests the native European dark bee was never entirely eradicated and may have remained in certain parts of the country, albeit in a form more adapted to current conditions than the original bee.
And Mr Carreck advocates breeding from bees already found in a location rather than those brought in from elsewhere, pointing to recent European research which found that in experiments across 11 different counties, honey bees originating locally consistently outperformed imported ones in their capacity for survival.
The popularity of imported honey bees is blamed by some for diluting local strains of the dark bee and their adaptations to local conditions.
The B4 project in Cornwall is a local breeding programme which aims to preserve the Cornish strain of Apis mellifera mellifera, the Cornish black bee.
Following on from Dr Thompson's work, their own DNA research has shown that on average, managed colonies in the UK still contain 45% of the native sub species' DNA.
Andrew Brown, founder of the B4 Project, said: "Until we deal with the health of our own colonies there won't be wild bees. We need to reduce the onslaught of importation, work with what we've already got in an area and localise bee breeding."
But the challenge these programmes face is promoting the native bee to other bee keepers in their locality.
Dr Giles Budge, from the National Bee Unit at Fera (Food and Environment Research Agency), is a lead partner in a proposed 8 million euros research project funded by the European Union to produce so-called "smart bees" that could answer that problem.
The SMARTBEES project is currently in contract negotiation but hopes to bring together scientists from across 11 European countries to try to preserve the genetic diversity of honey bees by drawing out traits that bee keepers want to use.
The approach follows the success of German and Italian breeding programmes which have produced productive, gentle, low swarming and varroa tolerant bees that beekeepers across the world want to keep.
"The exciting and novel approach of SMARTBEES is that we will use established protocols, developed by internationally recognised honey bee breeding experts, and apply them to local honey bee populations across the UK. By developing the genetic potential of our native bees and encouraging favourable traits, our consortium hopes to facilitate 'conservation via utilisation'," Dr Budge told BBC Nature.
"Another novel aspect of this project is that we will work with local beekeeping communities to breed from the bees they already keep, rather than using centralised national breeding centres that could produce stocks that are poorly adapted to regional climatic conditions and foraging landscapes.
"The scale of our approach and the genetic and breeding know-how supporting the improvement effort is unprecedented in European apiculture and offers huge potential to produce more resilient honey bee populations in the future."
Hive Alive broadcasts on BBC Two, Tuesday 15 July 2014 at 20:00 BST.