>
> >Re. N. ceranae, Ritter says that "[a]fter 24 hours of frost, the majority
> of spores are dead, while Nosema apis maintains its pathogenic power for
> longer."


I first learned about the susceptibility of N ceranae to cold shortly after
its discovery in the U.S.  I had sent fresh spore samples to Dr. Rob
Cramer, who refrigerated them over the weekend (as one would do for N apis
spores).  He was surprised that they became inviable after even short
refrigeration.

Drs. Ingemar Fries and Eva Forsgren later wrote a paper in Swedish (Nosema
ceranae fungerar inte som Nosema apis) on their testing.  After a week of
freezing, they couldn't infect bees with spores of ceranae, although apis
spores remained infective.

That said, Dr Frank Eischen later told me that there were infective spores
of ceranae on combs that had been in inheated sheds in the Midwest over
winter.

So, N ceranae spores appear to be more susceptible to cold, but some may
still survive.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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