Aaron asked about temperatures for killing AFB spores.
 
The following reference is one that you might start on:-
 
Thermal Resistance of Bacillus Larvae Spores in Honey by Eleanor J. Calesnick and Jonathan W. White Jr.  J. of Bacteriology Vol 64, 1952. pages 9-15.
 
As listed before I am currently involved in work on looking at heat treatment to kill AFB spores in beekeeping equipment.   The one thing we have found to date that it is not a simple answer.  Wet heat will kill spores in a very short time.  Lab trials showed a total kill on J agar plates of 1.5 X 10,000 in 30 minutes at 100 degrees centigrade.  A number of 5 X 10,000 took 35 minutes at 100 degrees.  At 110 degrees, spore numbers of 5 X 10,000 took 30 minutes.
 
When using a dry heat in the lab and using a higher number of spores, it was found that after 6 hours at a number of 3.6 X 1,000,000,000 there as no vegetative growth when cultured.  Raise the number to 6.5 X 1,000,000,000 then there were some growth when cultured.  Raising the number to 13 X 1,000,000,000 again gave cultures.
 
We also carried out some trials in a commercial timber drying kiln at 110 degrees and seeded 80 sites on bee boxes and we got 8 sites to give a vegetative growth after testing.  We had 6 controls outside the kiln which all gave vegetative growth after testing.
 
We are continuing with this trial so hopefully we will have more results at a later date.  In summary, AFB spores can be killed very easily in a wet condition but in a dry condition it is much harder.  In the timber drying kilns we were able to use steam but this still is regarded as a dry condition as the Equilibrium Mositure Content (EMC) within the hive is still very low.
 
I hope this is of some help, Aaron.  It probably raises more questions than it answers.
 
Trevor Weatherhead
AUSTRALIA