Each year, more than a million bumblebee colonies are imported by countries across the globe to pollinate a variety of crops, with the UK alone importing between 40,000 and 50,000. Although the colonies are said by the global suppliers to be disease free, a recent study in the Journal of Applied Ecology has found that more than three-quarters of those imported into the UK each year are riddled with parasites.
Bees and disease
Scientists purchased 48 commercially produced bumblebee colonies, each containing up to 100 bees, from three different European suppliers during 2011 and 2012, and screened each one for parasite DNA. The results showed that an alarming 77% of the colonies were infected with parasites, a situation which has serious implications for the health of the UK’s native wild bees and honey bees, many of which are already suffering severe declines.
“These parasites will undoubtedly be spilling over into wild and honey bees and very probably having negative effects on them,” said lead researcher Professor William Hughes, from the University of Sussex. “It is no great leap to think that damage is already being done.”
The results of the study revealed that the imported bumblebee colonies carried several different parasites, five of which were found in the bees themselves and three in the pollen provided by the suppliers as food. These parasites included three main bumblebee parasites (Crithidia bombi, Nosema bombi and Apicystis bombi), three honey bee parasites (Nosema apis, Ascosphaera apis and Paenibacillus larvae), and two which infect both bumblebees and honey bees (Nosema ceranae and deformed wing virus).
With the decline of pollinating insects in the UK in recent years, food producers are becoming increasingly reliant upon imported bees.
“Over a million colonies are imported globally – it’s a huge trade,” said Professor Hughes. “A surprisingly large number of these are produced in factories, mainly in Eastern Europe. We couldn’t grow tomatoes in this country without these bumblebees. We sought to answer the big question of whether colonies that are being produced now have parasites and, if so, whether those parasites are actually infectious or harmful.”
The potential impacts on native wild bee and honey bee species could be extremely severe, from harming the bees’ ability to learn, which is vital for finding food, to killing them outright. In Argentina, native bee species are already being driven to extinction as a result of imported parasites, and the authors of the recent study are recommending that urgent action is required in the UK to improve the effectiveness of disease screening and to close damaging loopholes.
Call for action
Scientists are calling for authorities to strengthen measures to prevent the importation of parasite-infected bumblebee colonies, by introducing proper colony checks upon arrival in the UK. While there are strict regulations in the UK regarding the import of non-native bumblebees, including ensuring that the colonies are disease free and are only kept in hives from which the queens cannot escape, no such regulations apply to imported colonies of native bee subspecies.
Bees and other pollinators are responsible for the production of three-quarters of the world’s food crops, but heavy pesticide use, rising disease, and starvation due to habitat destruction are all contributing to worrying declines in many species.
“The introduction of more or new parasite infections will, at a minimum, exacerbate this, and could quite possibly directly drive declines,” said Professor Hughes.
Earlier this week, the EU voted to successfully suspend the use of fipronil, a common pesticide, due to the serious risk it poses to bees. Currently used in more than 70 countries, this insect nerve agent will be banned from use on corn and sunflowers in Europe from the end of 2013.
Tonio Borg, European Commissioner for Health, said, “In the aftermath of the restriction on use of neonicotinoids, I pledged to do my utmost to protect Europe’s honey bee population, and today’s agreement with member states not only delivers on that pledge but marks another significant step in realising the commission’s overall strategy to tackling Europe’s bee decline.”
Find out more about honey bees on ARKive.
Kathryn Pintus, ARKive Text Author