[Pollinator] Bumblebees infected with honeybee diseases

[Matthew Shepherd]

From: BBC News

http://www.bbc.co.uk/news/science-environment-26242960 

 

19 February 2014 Last updated at 13:14 ET 


Bumblebees infected with honeybee diseases


By Rebecca Morelle Science reporter, BBC World Service 


"The most likely explanation is that the honeybees are acting as the source
of the virus for the bumblebees"


Prof Mark Brown Royal Holloway, University of London 

The beleaguered bumblebee faces a new threat, scientists say.

Researchers have found that two diseases harboured by honeybees are spilling
over into wild bumblebees. 

Insects infected with deformed wing virus and a fungal parasite called
Nosema ceranae were found across England, Scotland and Wales.

Writing in the journal Nature <http://dx.doi.org/10.1038/nature12977> , the
team says that beekeepers should keep their honeybees as free from disease
as possible to stop the spread.

"These pathogens are capable of infecting adult bumblebees and they seem to
have quite significant impacts," said Professor Mark Brown from Royal
Holloway, University of London.

Around the world, bumblebees are doing badly. 

In the last few decades, many species have suffered steep declines, and
some, such Cullem's bumblebee (Bombus cullumanus) in the UK, have gone
extinct. 

Scientists believe that the destruction of their habitats - particularly
wildflower meadows - has driven much of this loss, but the latest research
suggests that disease too could play a role.

The researchers looked at two pathogens commonly found in honeybees and
found they can also infect adult bumblebees.

In honeybees, deformed wing virus (DWV) causes significant problems. Its
severity seems to be exacerbated by the presence of another widespread
parasite, the varroa mite, causing entire colonies to collapse.

Bumblebees do not carry the varroa mite, but the scientists found that those
infected with DWV had a dramatically shortened lifespan. The fungal parasite
has also been shown to have an impact on bumblebee longevity.

Prof Brown said: "A significantly shorter lifespan in the field would impact
on their ability to go out and collect food and look after other bees."

The researchers found the diseases were already prevalent among wild
populations.

Looking at 26 sites across Great Britain and the Isle of Man, the
researchers found that about 11% of bumblebees were infected with DWV and 7%
were infected with the fungus. By comparison, about 35% of honeybees carried
DWV and 9% had the fungus. 

"A geographical patterning provides us with the information that
transmission is occurring among these animals - they are sharing parasite
strains," said Prof Brown. 

"We cannot say it definitively, but because of the epidemiology, the most
likely explanation is that the honeybees are acting as the source of the
virus for the bumblebees."

The team suspects that the same pattern will also be found around the world
- and says that controlling disease in honeybee hives is vital to stopping
the spread.

"We have to, at national and international levels, support management
policies that enable our beekeepers to keep their bees as free of diseases
as possible," Prof Brown said.

"The benefits are not just to the honeybees, they are to the wild bees as
well."

The researchers also want to investigate whether neonicotinoid pesticides
are playing a role in problem. 

A recent paper in the Proceedings of the National Academy of Sciences
<http://www.pnas.org/content/early/2013/10/18/1314923110>  journal suggested
that the chemicals are affecting the immune systems of honeybees, making
them more susceptible to pathogens.

"If bumblebees were exposed to neonicotinoids and had the same effect, you
would expect the bumblebee viral load to be going through the roof. This is
something we are hoping to test later," said Prof Brown.

In the European Union, neonicotinoids have been banned for two years because
of fears that they may be harmful to bees. But the British government
strongly opposed the plan, rejecting the science behind the moratorium. Both
Syngenta and Bayer, which manufacture neonicotinoids, are now taking legal
action against the European Commission in an effort to overturn the ban.

 

 

________

 

Matthew Shepherd

Communications Director

 

The Xerces Society for Invertebrate Conservation

Protecting the Life that Sustains Us

 

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