I started reading the mail from the bottom up, for a change, so, please,
Reimund, excuse me if I repeat this to Joel.
 
Dr. Rothenbuhler made research about the relationship between the
cleaning behaviour and resistance to AFB. His work was published in
English in 1958, 1964, 1967 and 1975. A digest of this accomplishment in
genetic improvement appears in the book edited by Dr. Tom Rinderer: "Bee
 Genetics and Breeding" (1986)in chapters 6 and 16. It contains
references.
 
I just wanted to pass on a very simple (I think) procedure to test the
cleaning behaviour, that was given to me. Prevention is better than
treatment and cheaper too.