Recent research

MANAGED HONEY BEES LINKED TO NEW DISEASES IN WILD BUMBLEBEES

Researchers have found that diseases commonly found in honey bees in the UK are now widespread in the wild bumblebee population, according to a new study published in Nature.

The team of researchers, including Dr Dino McMahon and Professor Robert Paxton, affiliated to Queen’s University Belfast (UK) and Martin-Luther-University Halle-Wittenberg (Germany) as well as the German Centre for Integrative Biodiversity Research at Halle-Jena-Leipzig, in collaboration with Dr Matthias Fürst and Professor Mark Brown from Royal Holloway University of London (UK) and Professor Juliet Osborne at the University of Exeter (UK), say the research provides vital information for beekeepers across the world to ensure that their honey bee management supports also wild bee populations. Professor Paxton said: “This is a very important finding for beekeepers, as controlling disease in honey bee colonies is vital to stopping the spread of disease within and between bee species. Wild bees are in decline on a worldwide scale.”

This research assessed common honey bee diseases to determine if they could pass from honey bees to bumblebees. It showed that deformed wing virus (DWV) and the fungal parasite Nosema ceranae - both of which have major negative impacts on honey bee health - can infect worker bumblebees and, in the case of DWV, reduce their lifespan. Honey bees and bumblebees were collected from 26 sites across the UK and screened for the presence of the parasites. Both parasites were widespread in bumblebees and even more so in honey bees across the UK.

Dr Fürst explained: “One of the novel aspects of our study is that we show that DWV, which is one of the main causes of honey bee death worldwide, is not only broadly present in bumblebees, but is actually replicating inside them. This means that it is acting as a real disease; they are not just carriers.”

The researchers looked also at how the diseases spread and studied genetic similarities between DWV in different pollinator populations. Three factors suggest that honey bees are spreading the parasites into wild bumblebees: honey bees have higher background levels of the virus and the fungus than bumblebees; bumblebee infection could be predicted by patterns of honey bee infection; and honey bees and bumblebees at the same sites shared genetic strains of DWV.

“Parasites are probably the major cause of honey bee losses,” said Professor Paxton. “Our novel data using high-resolution genetic markers have allowed us to trace individual strains of virus and show that their transfer between honey bees and bumblebees is on-going - right now, in the UK and possibly elsewhere in the world where honey bees are heavily infected with DWV.”

While recent studies have provided anecdotal reports of the presence of honey bee parasites in other pollinators, this is the first study to determine the epidemiology of these parasites across the landscape. The results suggest an urgent need for management recommendations to reduce the threat of emerging diseases to our wild and managed bees.

Professor Brown added: “National societies and agencies, both in the UK and globally, currently manage so-called honey bee diseases on the basis that they are a threat only to honey bees. While they are doing great work, our research shows that this premise is not true, and that the picture is much more complex. Policies to manage these diseases need to take into account threats to wild pollinators and be designed to reduce the impact of these diseases, not just on managed honey bees but on our wild bumblebees too.”

This study is part of the Insect Pollinators Initiative, joint-funded by the Biotechnology and Biological Sciences Research Council (BBSRC), Defra, the Natural Environment Research Council (NERC), the Scottish Government and the Wellcome Trust. It is managed under the auspices of the Living with Environmental Change (LWEC) partnership.

The full paper can be read at: http://www.nature.com/nature/journal/v506/n7488/full/ nature12977.html

FÜRST M.; MCMAHON D.; OSBORNE J.L.; PAXTON R.J; BROWN M.J.F. (2014) Disease associations between honeybees and bumblebees as a threat to wild pollinators. Nature 506, 364-366. DOI: doi/10.1038/nature12977

Bombus terrestris

PHOTO © JEFF HAYWARD 2013