Dr. Jochai Weiss, who worked for decades in extension work in Israel 
until the 1980s, presented a useful concept based on his experience: 
AFB is not a disease of the bees, but of the comb.  The main source of 
infective risk to a colony lies in the wax of brood cells since AFB 
produces very persistent spores which can accumulate to highly 
infective doses in brood cells.  Beyond this primary point 
source clearly other factors play supporting roles: hygienic removal by 
workers, incoming spores from robbed colonies, spores on woodenware, or 
treatment by antibiotics.  On the latter, Dr. Weiss insisted that 
treatment just masks temporarily the disease by interrupting the cycle 
of infection, yet the primary source of infection remains in the comb 
even after treatment.  Hence the effectiveness of burning comb.

The apparent reduction in AFB in the US in the last two decades is 
intriguing.  Some have speculated that it has to do with a major 
improvement in hygienic activity.  It is also possible that increased 
mortality from varroa (and mothing out of comb) is producing a lot of 
comb turnover, especially in operations with no treatment, which are 
likely the ones more prone to infection and robbing.

 

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