>>> I tried feeding the observation hive...
>>> but they were not interested in any syrup.
>
>> Not taking feed is classic of nosema cerana.
>
>Agreed.
>This is the simple answer, the one that fits the
>list of symptoms described.

Interesting, please produce reference material for ‘not taking feed is classic of NC‘.

I would like to suggest also, that we resist the urge to categorically ‘rule out’ other causes.  Therefore I am going to disagree with the ‘one that fits‘ comment, in favor of suggesting we adopt a more ambiguous “one of several” that may fit diagnosis.  

There are many reasons why bees sometimes wont take feed.

Maybe Grant can confirm or deny.  
But I will stick my neck out here and hope to confirm my statement by making a confident prediction. I believe the reason why the syrup wasn’t taken was because feeding wasn’t started during the early stages of this event.  ONLY after dwindling was under way, and stress observed in the colony was feeding started.  I will retract and yield to considering the N.C. analysis if Grant says ‘he has been feeding all along’ or ‘he has been feeding before dwindling and reduction of brood symptoms appeared‘. 

Why do I consider the timing of feeding important?

When colonies begin to fail due to any environmental influence, there begins a change, -stresses from the failing brood nest creates a stress of its own, this stress creates different stresses and so fourth, impacting colony functions, with the colony needing to constantly adjust division of labor as stresses accumulate.  Severely stressed and dwindling colonies can reach a point of disarray, where they can no longer mount an efficient and effective division of labor.  Colony functions once considered vital to the colony,  may no longer have the priority they once had, OR the  colony may lack the capability needed to perform them. 

Remembering the great Brother Adam, and I think Bevan also stated that a honeybee colony is a living organism.  A colony at this stage of decline is no doubt a distressed organism,  and distressed organisms do not function properly.  What do distressed and dying organisms do?,,, they end up needing to cut other functions and resort to keeping the heart and brain of the organism beating, which in honeybees is what?,,, "the brood nest".    IMO, it is not surprising that the bees in the observation hive ignored the syrup, because this was perhaps no longer determined by the colony to be a vital and necessary function.  Assuming here, that tending, feeding and keeping brood and queen warm would take priority over accessing the syrup, even if it means certain death to the colony.  Therefore, we must consider that this symptom has nothing to do with the cause of the event, and more to do with the ‘art of dying. 

I recall the devastating losses during the winter of 95-96 when we tried to save the last remaining colony in my operation by installing it in the OB hive the heated bee house.  The colony, was determined on keeping the broodnest heart and brain functioning, and it did not mount effective division of labor to access any syrup that we provided.  We resorted to feeding directly to the bees in the broodnest with an eye dropper.   

As Shepard wrote about ‘bi-directional selection’.   We must also be wary that symptoms can be ‘bi-directional’ in how we choose to interpret them. 

Best Wishes,
Joe


      

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