I just found this.
Asian Parasite Killing Western Bees - Scientist
SPAIN: July 19, 2007
MADRID - A parasite common in Asian bees has spread to Europe and the
Americas and is behind the mass disappearance of honeybees in many
countries, says a Spanish scientist who has been studying the phenomenon
for years.
The culprit is a microscopic parasite called nosema ceranae said Mariano
Higes, who leads a team of researchers at a government-funded apiculture
centre in Guadalajara, the province east of Madrid that is the heartland
of Spain's honey industry.
He and his colleagues have analysed thousands of samples from stricken
hives in many countries.
"We started in 2000 with the hypothesis that it was pesticides, but soon
ruled it out," he told Reuters in an interview on Wednesday.
Pesticide traces were present only in a tiny pro****tion of samples and
bee colonies were also dying in areas many miles from cultivated land,
he said.
They then ruled out the varroa mite, which is easy to see and which was
not present in most of the affected hives.
For a long time Higes and his colleagues thought a parasite called
nosema apis, common in wet weather, was killing the bees.
"We saw the s****es, but the symptoms were very different and it was
happening in dry weather too."
Then he decided to sequence the parasite's DNA and discovered it was an
Asian variant, nosema ceranae. Asian honeybees are less vulnerable to
it, but it can kill European bees in a matter of days in laboratory
conditions.
"Nosema ceranae is far more dangerous and lives in heat and cold. A hive
can become infected in two months and the whole colony can collapse in
six to 18 months," said Higes, whose team has published a number of
papers on the subject.
"We've no doubt at all it's nosema ceranae and we think 50 percent of
Spanish hives are infected," he said.
Spain, with 2.3 million hives, is home to a quarter of the European
Union's bees.
His team have also identified this parasite in bees from Austria,
Slovenia and other parts of Eastern Europe and assume it has invaded
from Asia over a number of years.
Now it seems to have crossed the Atlantic and is present in Canada and
Argentina, he said. The Spanish researchers have not tested samples from
the United States, where bees have also gone missing.
Treatment for nosema ceranae is effective and cheap -- 1 euro (US$1.4) a
hive twice a year -- but beekeepers first have to be convinced the
parasite is the problem.
Another theory points a finger at mobile phone aerials, but Higes notes
bees use the angle of the sun to navigate and not electromagnetic
frequencies.
Other elements, such as drought or misapplied treatments, may play a
part in lowering bees' resistance, but Higes is convinced the Asian
parasite is the chief assassin.
Story by Julia Hayley
REUTERS NEWS SERVICE
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