Veganwolf.com
Honeybees under attack on all fronts
The New
Scientist February 16, 2009
http://www.newscientist.com/article/mg20126954.600-honeybees-under-attack-on-all-fronts.html
Honeybees
under attack on all fronts
By Debora MacKenzie
THE world's
honeybees appear to be dying off in
horrifying numbers, and now consensus is
starting
to emerge on the reason why: it seems there is no
one cause.
Infections, lack of food, pesticides
and breeding - none catastrophic on
their own -
are having a synergistic effect, pushing bee
survival to a
lethal tipping point. A somewhat
anti-climactic conclusion it may be, but
appreciating this complexity - and realising
there will be no magic
bullet - may be the key to
saving the insects.
A third of our food
relies on bees for
pollination. Both the US and UK report losing a
third
of their bees last year. Other European
countries have seen major die-offs
too: Italy,
for example, said it lost nearly half its bees
last year.
The deaths are now spreading to Asia,
with reports in India and suspected
cases in
China.
But while individual "sub-lethal stresses" such
as infections are implicated, we know little
about how they add
together. The situation should
become clearer in the next few years as the
US
government, the EU and others are pouring money
into bee research.
The UK, for example, has
doubled its annual research budget, allocating
£400,000 a year for the next five years.
On top of that, the UK
National Bee Unit will get
£2.3 million to map the problem. This money is
urgently needed, says Peter Neumann of the Swiss
Bee Research Centre in
Berne, who runs COLLOSS, a
network of researchers studying colony loss in 36
countries. "We don't have the data to assess the
situation in Europe,
never mind the world," he
says.
The main stress facing bees is the
varroa mite, a
parasite from Siberia that has now spread
everywhere but
Australia. Mite infestations
steeply reduce bees' resistance to viral
infection. Worryingly, the mites are developing
resistance to the
pesticides used to control
them, forcing beekeepers to use methods that are
often less effective.
French and German beekeepers blame their losses
on insecticides called neonicotinoids - but
France banned them 10 years
ago and its bees are
still dying. Neumann suspects a wider problem,
citing experiments showing that agricultural
chemicals that are safe for
bees when used alone
are lethal in combination. "Farmers increasingly
combine sprays," he says. They also leave few
flowering weeds, depriving
bees of essential
nutrients from different kinds of pollen, he
adds.
Meanwhile viruses may cause a syndrome dubbed
colony collapse
disorder (CCD) in the US, in
which adult bees abandon their hive, leaving
the
healthy queen and young bees to die. Diana
Cox-Foster of Penn State
University in University
Park, where the syndrome was first identified,
says viruses, including one called IAPV,
duplicate the symptoms of CCD
in her greenhouse
studies. There is no IAPV or CCD in the UK, says
Mike
Brown of the National Bee Unit, yet bees are
still dying.
At the root
of the vulnerability to these
stresses could be the way breeding has
affected
the bees' genetic make-up. By being highly
selected for
calmness and honey production,
honeybees have lost other useful
characteristics,
says Francis Ratnieks of the University of
Sussex, UK.
In research to be published in the
journal Heredity, he describes a way to
breed for
"hygienic" bees that, unlike most commercial
bees, clear out
infected young and can resist
varroa mites.
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