> Spores remained viable in the alimentary canal for a period of at
> least 40,000 min. Viability was demonstrated through the growth of B.
> larvae colonies in solid yeast-starch medium. When fed to young honey
> bee larvae, these spores proved to be infectious and caused American
> foulbrood disease.

Unless there is more detail, this is a rather crude examination of the
question.  I'm not saying that the study is invalid, but that it is very
preliminary and the results appear binary, when there may well be a
continuum.

Potency of spores will deteriorate over time and under various
conditions.  Moreover there are various strains of AFB and bee strains
vary in larval resistance to infection.

Simply showing that infection is possible, does not show whether the
probability of infection is reduced or whether many more of the digested
spores are required than fresh spores.

It seems to be accepted now that AFB spores that are covered in wax and
propolis while aging in beehives are significantly reduced in potency or
at least likelihood to infect.  I recall debating this at length in an
atmosphere of total disbelief the past.

Many of these matters are not yes/no questions, but questions of
distribution, probability and time decay.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html