Hello All,
quick answer:
Spores are viable on comb for *at least* 6 months to a year. Jerry Hayes 
quote from his January ABF "classroom". Jerry is a member of the CCD working 
group.

Not sure how long comb would need to sit for the nosema spores to not be 
viable on comb. I personally am now treating ALL deadouts from the season 
before with acetic  acid before adding bees.

I would guess spores exposed to sunlight  would  not be as viable as long 
but only a guess.

Radiating comb is too expensive in my opinion and acetic acid does as good a 
job in my opinion.(as far as nosema ceranae spores are concerned)
bob 

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