In Alberta, we were suffering increasing winter loss the past few years. 
There were a number of possible explanations, but the most obvious were 
diminishing control of varroa, accompanied by apparently lower economic 
thresholds and increased incidence of nosema and higher spore counts in 
infections.

The response was to obtain a new approved treatment for varroa and recommend 
proactive feeding of fumagillin, accompanied by a completely voluntary 
extension program to put fieldmen in apiaries at crucial times of year to 
co-ordinate and  confirm procedures and to gather samples.  This created a 
treatment and monitoring feedback loop.  Nutrition is also emphasized and 
most beekeepers are applying patties in spring.

From all indications, this focused effort is working.  Beekeepers report 
having too many bees and are scouting around for anything they can find in 
anticipation of having to split.

Although, we might just be lucky, and maybe the improved survival has 
nothing to do with all that work, on the surface, this experience seems to 
prove the old saying that you make your own luck.

In regard the ongoing discussion, think that the following somewhat sobering 
snip from Randy's pages provide food for thought and may focus attention on 
the central questions.  See
http://www.scientificbeekeeping.com/index.php?option=com_content&task=view&id=54
for the full article.

--- begin quote ---

Notes from the 2008 ABF/AHPA & American Bee Research Conference

The Spanish team of Drs. Mariano Higes (pronounced Ee' hase, with a strong 
"h"), Raquel Martín-Hernández, and Aránzazu Meana gave compelling 
presentations detailing their investigation into Spanish colony collapses. 
They found N. ceranae to be the culprit.  The symptoms appear to be 
strikingly similar to CCD (however, it is clear that there are colonies 
collapsing in the US without detectable nosema).  Drs. Steve Pernal and Tom 
Webster independently presented  findings on treatments, and Dr. Judy Chen 
showed incredible graphics on the genetics and molecular biology of the 
beast, plus details of the progression of infection within the bee body.  I 
will discuss information from these, and other presenters elsewhere in this 
article, and cite them as "2008 Conf."

Genetically, N. ceranae appears to be cousin to N. apis, rather than 
sibling.  Evidence presented separately by Geoff Williams and Judy Chen 
indicate that ceranae  is more closely related to N. bombi (from bumblebees) 
or N. vespula (from wasps and some other insects), which helps explain why 
the European honey bee lacks resistance to it, and suggesting that it may 
spread to other bees.

Don't expect to diagnose nosema infections without a microscope--Chen and 
the Higes team both found that ceranae infection does not produce dysentery, 
swollen abdomens, a white gut, nor "crawlers" (although I find a few 
infected crawlers in my yards).

Higes and Meana explained that the pathogenesis of ceranae infection in a 
colony progresses through four stages:

Asymptomatic-the infection builds slowly the first year, goes unnoticed, but 
can be detected microscopically in foragers.

Replacement--The bees rally by rearing more brood, even through winter.

False Recovery-- This may occur the second summer, during which the colony 
rebounds somewhat.  However, in this phase the infection starts to move into 
the house bees.

Depopulation and Collapse--Finally, the bees "lose ventricular function" 
(they can no longer digest food), stop eating (and stop taking medicated 
syrup, or pollen supplement), and simply starve to death in the midst of 
plenty.  Most adults die far from the hive, leaving only a handful of young 
bees and the queen.

Colonies can collapse either during summer or winter, but the character of 
the infection differs.  During cold season collapse, most bees are infected, 
and spore counts exceed 10 million spores per bee.  Contrarily, under warm 
season breakdown, less than half the bees are infected, and spore counts are 
generally much lower.  Forager bees just die in the field, and the colony 
shows no symptoms other than dwindling away.

The Spanish researchers generally don't count spores, however.  To them, a 
colony is either "clean," with zero spores, or infected, and on its way to 
eventual collapse unless treated with fumagillin.  This knowledge makes 
accurate spore counting rather moot, and home diagnosis with a 'scope even 
easier.  When you first start finding spores at a low level, it means that 
you'd better start taking action, and don't expect the colony to deal with 
the disease by itself.  In subsequent correspondence, Dr. Higes asked me to 
make clear that the percentage of bees infected is of more importance than 
overall spore count.
 

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