This is an interesting discussion.  However I get the feeling that people want to tie dying hives 
to immediate presence of nosema and to a lesser extent, the presence of nosema to CCD.  
However this overlooks the mechanism of nosema's effect on the hive.

Nosema's vegetative stage infects the gut thereby decreasing absorbtion of nutrients - more 
importantly - amino acids (protein building blocks).  Higher infection, less absorbtion and vice 
versa.  But with lots of the right pollen with good quantities of the right amino acids, bees are 
still able to absorb enough (or nearly enough) of the right protein building blocks - even with 
quite high infections.  But poor pollen sources (or pollen lacking one or more essential amino 
acids) may cause a light infection to be a significant problem.   

Good protein bees live longer.  Work done by Graham Klienschmidt in Australia in the 70s 
directly correlated raw crude protein levels of bees to lifespan.  From memory, good protein 
(50%+) and workers lasted 6 weeks on a flow.  Poor protein (less than 40%) and that didn't 
make it to 3 weeks with obvious implications for hive populations, winter bees, time to rebuild 
populations etc.  (Doug Somerville has continued to build on this work and I highly 
recommend becoming familiar with these concepts.  Look at 
http://www.rirdc.gov.au/reports/HBE/05-054sum.html) 

Bees without enough protein sources to feed brood are able to mine the protein in their own 
bodies to feed brood, so a short dearth of protein (or even a specific amino acid missing from 
the presently available pollen) can be overcome and hardly a hiccup is seen in the hive 
population as low protein bees give way to high protein bees once good protein sources 
become available.  Likewise a short term nosema infection can present minmal effect on hive 
populations as long as the oncoming generations are able to receive sufficient protein of the 
right sort.

The point here is that the collapse of the hive is not due to the immediate ravages of infection 
but rather the premature death of an entire genaration of bees (due to a greatly reduced 
longevity from poor protein levels) that may be one or more generations removed from the 
cause - and here we are talking nosema but it could be poor pollen source.

By the time this happens, the nosema infection may be mostly history........ and insignificant 
enough to be overlooked as the smoking gun.

Regards,
Peter Bray

PS  It would be very interesting to test the raw crude protein levels of bees that are left after a 
CCD diagnosis.
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