- Reptile Conservation Resources, Inc

Note from Frank - This article reminds us again of our need to realize how all of our actions with nature are interrelated and how all of the ramifications of any action affecting the natural world must be considered:


Disease spread to wild bumblebees from commercially bred bumblebees used
for pollination in agriculture greenhouses may be playing a role in the
mysterious decline in North American bee populations, researchers said
on Tuesday [22 Jul 2008].

Bees pollinate numerous crops, and scientists have been expressing
alarm over their falling numbers in recent years in North America.
Experts warn the bee disappearance eventually could harm agriculture
and the food supply.

Scientists have been struggling to understand the recent decline in
various bee populations in North America. For example, a virus,
Israeli Acute Paralysis Virus, brought from Australia has been
implicated in massive honeybee deaths last year [2007] — see ProMED
archives below.

Canadian researchers studied another type of bee, the bumblebee, near
2 large greenhouse operations in southern Ontario where commercially
reared pollination bees are used in the growing of crops such as
tomatoes, bell peppers, and cucumbers.

The researchers first observed that the commercial bumblebees
regularly flew in and out of vents in the sides of the greenhouses,
escaping from the facilities.

The researchers then devised a mathematical model to predict how
disease might spread from this “spillover” of runaway commercial bees
to their wild cousins. The model predicted a relatively slow build-up
of infection in nearby wild bumblebee populations over weeks or months
culminating in a burst of transmission generating an epidemic wave
that could affect nearly all wild bees exposed. The model also
predicted a drop-off in infection rates as you get further from the

The researchers then sampled wild bumblebee populations around the
greenhouses, catching bees in butterfly nets, holding them in vials,
and taking them back to a laboratory to screen for pathogens,
including testing their feces.

The patterns that had been predicted by their mathematical model were
borne out by studying the wild bees, they said. Most of the parasites
in the wild bumblebees were found to be at normal levels except for
one intestinal parasite known as _Crithidia bombi_ that is common in
commercial bee colonies but typically absent in wild bumblebees.

The researchers found that up to half of wild bumblebees near the
greenhouses were infected with this parasite. “All of the different
species of bumblebees that we sampled around greenhouses showed the
same pattern: really high levels of infection near greenhouses and
then declining levels of infection as you moved out,” said Michael
Otterstatter of the University of Toronto, one of the researchers.
“It was quite obvious that this was coming from the greenhouses and
it was a general adverse effect on the bumblebees,” Otterstatter
added in a telephone interview.

He said the parasite weakens and often kills bees. The “spillover” of
disease from commercial colonies may be a factor in the decline of
bee populations in North America, he added.

The study, published in the Public Library of Science journal PLoS
ONE, is available at

[Byline: Will Dunham]

Posted by Frank - July 28, 2008

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