By Mark Ward BBC News website
|

The varroa mite has devastated bee colonies all
over the
world |
The US
is in danger of running out of honey bees to pollinate its almond
crop - the country's number one horticultural export.
February and March are the crucial months for almond growers, as
this is when trees blossom and need pollinating.
At this time of year, owners of commercial hives take their
valuable cargos to California, where almost 80% of the world's
almonds are grown, to service the blossom.
Annually the crop is worth more than $2.5bn and a lot of jobs
depend on a good harvest, explains Dan Cummings, one of the
directors of California's Almond Board and head of its bee task
force.
Currently about 222,000 hectares are under production to grow
almonds. Mr Cummings expects this to grow to 330,000 hectares over
the next five years.
But, said Mr Cummings, that growth presented a real problem.
"Roughly two-thirds of the bees in the US need to come to
California for almond pollination," said Mr Cummings. "Beekeeping in
the US is very much migratory."
Hive mind
The danger is that as the demands of almond growers for healthy
hives grow, America will simply not have enough commercial colonies
available to travel. Bees travel from as far away as North Carolina
to California just so they can be used at the key pollination
season.
"Last year we were a little short," said Mr Cummings.
Already, he said, demand for colonies was driving up the price
that beekeepers charged for renting out their colonies.
Mites stunt bee growth and make them vulnerable
to disease |
In
2004, beekeepers could get, on average, $54 for every hive they sent
to almond groves in California. Last year, prices peaked at about
$85, and in 2006 there are reports of owners charging more than
$150.
To make matters worse, American bees are suffering a resurgence
of debilitating attacks from the varroa mite. These tiny parasites
stunt the growth of bees, sap hive resources and slowly kill off the
colony.
Unfortunately, said Mr Cummings, bee colonies badly affected by
varroa typically collapsed at about the same time as almond trees
came into flower.
While chemical treatments can help manage the problem, many
pesticides have been so widely used that some mites have developed
resistance.
Finding a better way to manage mites had become a pressing
problem, said Mr Cummings, because of the tight relationship between
the health of beehives and the size of the almond crop.
Chemical control
American beekeepers are now turning to a British development to
help them tackle resistant varroa mites.
Developed by Vita Europe, the thymol-based treatment is derived
from thyme, and vapours from oil extracted from the herb have proved
useful in killing the varroa mites.
Dr Max Watkins, technical director of Vita Europe, said: "Thymol
works in a very different way from traditional pesticides which
target specific points on the nervous system."
By contrast, he said, thymol has a much wider effect on varroa
physiology.
In tests, thymol had been able to knock out more than 90% of the
mites in a colony, said Dr Watkins.
"It's a little more difficult in theory for something to become
resistant to that," he added.
Dr Watkins explained that thymol tended to knock out both
resistant and non-resistant varroa mites, so beekeepers could use it
in rotation with established treatments to keep the numbers of
parasites under control.
Vita's anti-varroa treatment is now undergoing certification in
the US.
Although certification will come too late for the 2006 almond
pollinating season, Dr Watkins expects it to be in wide use to
prepare bees for the 2007 crop.