>In light of this conversation I'd love your input on this article re
current research findings. It seems to indicate that colonies are weakened
by chem load and then more susceptible to pathogens when exposed.

Andrea, one must be careful about making assumptions.  You apparently
assumed that the bees were more susceptible to pathogens after exposure.
The study didn't find that.  It only found that there appeared to be an
association between exposure to some pesticide residues, and a greater
prevalence of nosema infection in those bees that ate pollen containing
those residues.

One cannot assume that this applies to all pathogens (although this is
likely).  One cannot assume that the reason for the increase prevalence to
nosema was due to increased susceptibility.  The observed results could
have been due to the pesticide having a hormetic effect upon nosema,
causing it to replicate at a higher rate.

Now please don't misinterpret me!  The effect could well have been due to
depressed immune function.  All that I'm saying is that one must be careful
of assuming what were the mechanisms involved.

>I am also specifically interested in any insights you might have as to
> chems that enter waterways through runoff
>

Some aquatic species (notably the mayflies, caddisflies, and stoneflies)
are highly susceptible to water quality changes, including fertilizers,
sediment, temperature, pollutants, and pesticides.  Species diversity has
long been observed to decrease downstream from ag (or urban) runoff.
(FWIW, I have a background in sampling of aquatic inverts to detect the
effects of water pollution).

Unfortunately, a couple of new studies that have "made a link" between
decreased species diversity and exposure to imidacloprid were poorly
designed or interpreted.  So yes, one can safely assume that pollution in
ag runoff is tough on many aquatic species.  But I have yet to see anyone
take the time to do a good analysis of existing databases (such as that
from the Netherlands) to look for risk factors due to each individual
pesticide.  It is disappointing to me that researchers are focusing solely
upon imidacloprid, when there are so many other pesticides and pollutants
involved.

And Pete asked: >How often does this occur? According to the news media,
about one third of the hives do this every year.

Sudden colony depopulation with healthy-appearing brood present does not
occur as often now as it did from 2004-2008.  And even then, many
depopulations occurred during winter, when little brood was present.

 >And yet, I have only seen one photograph where the bees were gone and the
hive had large amounts of apparently healthy brood.

I have plenty of photos.  This is a problem--unless you have actually
observed colonies collapsing with CCD symptoms, it is hard to get your mind
around.  When you actually observe the rapid depopulation occurring, it is
mind blowing.  Dr.  Eric Mussen and I shared this experience together, and
will never forget it!

Pete, despite the fact that neither your nor Bob Harrison ever observed
"classic" CCD, those affected beekeepers had seen plenty of varroa/virus
collapses before, and could easily see the difference.  The bees in the
hive behave differently prior to the sudden depopulation.  It was a new
phenomenon in the experience of all that I have spoken with.

 >Whereas I have seen thousands of hives where the bees just disappeared,
leaving wrecked brood, mites, and obvious mite damage.

To be classified as CCD, there can be no signs of obvious mite damage.

Pete, it is unfortunate that you were not able to view my presentation in
New York last week.  I showed slides of the step-by-step progression of
sudden colony depopulation.

I still observe it each spring in February here in Calif.  N ceranae is
often associated.  We will have a much better understanding of the
phenomenon when Dr. Merav Galit finishes analyzing the data from last
winter's large-scale trial.


>What? What changed? How do we know this was not going on all along and
this is when it caught people's attention?

It has occurred historically, you know that!  Sudden colony depop with
brood present is a "traditional" symptom of high nosema infection.  In
addition, with the elevated presence of viruses in hives since the arrival
of varroa, colony depop has become more common.  It is clear to me, from my
inoculation experiment, that certain strains of those viruses can initiate
sudden colony depop.

The problem is, that the media refer to any form of colony morbidity or
mortality as "CCD."  This is a huge mistake, and leads to great confusion
on the part of the public.


-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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