[log in to unmask] writes:

<agreeing that liquid nitrogen freeze method is the "best"  higienic
behaviour test method I wonder How far off are the other methods?  is there
a relation between the methods?>
 
We spent two years on this.  None of the other methods were reliable  
predictors.  Too many false positives, indicating colonies displayed  hygienic 
behavior when in reality they did not.  This is the reason we  developed a 
consistent method for EPA.    
 
Allen is also right, dry ice is not fast, specific, or cold enough.   You  
want a fast freeze, constrained to the test area(s) with minimal  damage to 
the comb.  You don't want to slice up the comb OR have a broad  area (cold 
in the middle, grading out to various degrees of freezing)  impact.
 
We recommend freezing circles of about 2-3 inches or 5-8 cm MAX.   Three to 
5 circles, spread over at least two frames is far better than one large  
circle.
 
Jerry         

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