> However this overlooks the mechanism of nosema's effect on the hive.

This is an excellent point.  I have been wondering whether such an effect 
occurred in the French sunflower fields.
the colony collapses that were blamed on Gaucho occurred at the same time 
that French bees were invaded by N ceranae.
Sunflower pollen is noted as being nutritionally incomplete to bees.
I've been wondering if nosema simply caused the massive colony deaths by 
exascerbating the problem of poor amino acid availability in the sunflowers.
Randy Oliver 

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