RE: AFB, Bailey states

Larvae are most unlikely to be affected, however, even by 10,000 or more spores, unless they ingest the spores within the first two of the five days they spend growing in open cells, i.e., almost five or six days at least before they are killed. Larvae younger than 24 hours old are most susceptible, and can be infected by 10 or fewer spores. The reason for the resistance increasing with larval age is unknown, but is clearly of great importance in the spread of infection. Colonies of some bee strains resist spread of infection better than others. One reason is that the increasing resistance with increasing age of larvae differs between bee strains.

There are further hereditary factors causing strains of bees to differ in
their ability to resist spread of infection. Adult bees of inbred resistant
strains detect diseased larvae mostly in their eighth or ninth day of larval
life, when they have died in their sealed cells but have not yet formed infective
spores, whereas adult bees of inbred strains especially selected for
susceptibility leave most dead larvae long after spores have formed.
The bees eventually clear almost all of these spores away from the colony:
the proventriculus removes ingested spores from food in the crop quickly
and equally efficiently in susceptible and resistant bees.

             ***********************************************
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