I've been looking through Randy Oliver's articles/posts re. Nosema ceranae on Scientific Beekeeping as well as this LIST-SERV for references to managing Nosema ceranae by freezing comb.  No luck thus far (I must be blind). Deep-freezing "food combs for at least 24 hours" is recommended by Wolfgang Ritter in his Bee Culture article of 25 May 2015 - "Practical Beekeeping: Beekeeping with the 'New' Parasite." http://www.beeculture.com/practical-beekeeping-beekeeping-with-the-new-parasite/ 

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." Can any of you corroborate the freeze kill part of this with scientific data or direct experience?  In any event I find the management recommendation a bit imprecise. What does "at least" 24 hours mean empirically? Does it mean that x% of the spores are killed in 24 hours but one must freeze in a domestic freezer for 72 hours in order to kill 100% of the spores?  What does the "majority" of spores mean? 75%, 90%? I am reluctant to recommend  freezing comb as a management tool based on this kind of imprecision. Your thoughts, please?

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