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Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
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Sun, 19 Sep 2010 10:00:32 -0600
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> Randy & I have seen virus issues in hives with low varroa loads but only 
> in my case in the last decade and healthy strong hives (sitting on the 
> same pallet) are unaffected.

This is quite common.  It seems that there is a combination of factors 
involved.  Maybe just the genetics of that particular hive and the virus, 
but probably more factors combine IMO.

> However the discovery of widespread nosema ceranae (NC) and NC replacing 
> nosema apis was big news. In fact most of us consider the discovery of NC 
> in our bees very helpful in keeping healthy bees.

Do we know for sure how long nosema ceranae has been around in North 
America?    Last I heard, the earliest date was being pushed back a decade 
or decades.

Back in the '70s, nosema was being identified as a huge burden for honey 
bees, costing beekeepers fortunes and fumagillin feeding was recommended. 
The we had decades where Nosema was undetectable in many outfits.  I gave 
away my last two big bottles in 2003 because I had no  detectable nosema.

Something is going on.  Why has nosema suddenly become a problem again?  I 
think there has to be a co-factor at work.  People have been unable to 
replicate the Spanish work although nobody questions the rigour of the 
Spanish work.

> Control mite levels and nosema ceranae spore levels is a first step in my 
> opinion to keeping healthy bees.
    and
> When hives are over varroa threshold they are *in my opinion* impossible 
> to save.
    and
> The key point here is that yes, there were high varroa levels but not 
> significantly higher than what you'd expect to see. And the symptoms were 
> different from what you would expect to see with varroa levels that high.

OK.  What are the thresholds are we discussing here?  Can we put numbers to 
them or just speak very generally?  I understand that the threshold depends 
somewhat on location and time of year as well as other factors, but I'm more 
comfortable if writers at least attempt to use metrics.  Where they don't, I 
have less confidence in what is being written.

My understanding is that anything over about 6% phoretic, measured while 
there is normal brood in the hive is the divide between a hive that may be 
saved easily by a chemical strip and a hive that may be beyond saving, 
depending on conditions.  Of course these measures are not cut and dried, 
since the thresholds are about probabilities over time and there are 
exceptions, especially in the short run.

6% is 18 mites in 300 bees and we see this from time to time in our 
inspections during the brood season.  In Alberta, we try to stay well below 
that level and use one or two percent as thresholds, depending on time of 
year and the range we see in yards.  Anything approaching 5% is cause to hit 
the panic button.

> the problem of bee decline has not been solved. Bees are declining in many 
> locations throughout the world. Sometimes the cause and treatment is 
> obvious, sometimes not.

We have not discussed this much here.  The talk of worldwide bee decline is 
widespread and motherhood issue, but I am not very convinced that the 
reported declines are not local and/or an artefact of the sampling reports 
and the need of various people and organisations to achieve various 
political and funding agendas.

Looking at just the honey bee: If the honey bee is threatened worldwide, 
then why do we have surpluses of honey on the world market?  The decline in 
numbers of bees under management in the USA is strictly related to 
economics, changing work environment and social expectations,  and loss of 
places suitable for bee yards.  In other countries, the numbers are 
increasing, sometimes drastically.

> I think folks are making a big mistake belittling the work that is being 
> done. Before, everyone was lamenting the lack of money being spent on bee 
> research and now they are belly aching because we still haven't found out 
> what they want to know.

There is a difference between belittling and criticizing.  Also, personally, 
I cannot belittle or criticize work because it is not being well 
communicated and because we are not getting hard facts, just vague 
descriptions.  In  fact I am criticizing that very lack of good and 
precisely criteria. 

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