One thing I recall from listening to Dr. Peng quite some time back was that the dosage window between OTC toxicity and ineffectiveness for prevention of AFB in pupae is quite narrow.  Additionally, the window in time for brood infection is also narrow.

Considering that, and the widely varying OTC doses and application methods used by beekeepers, it seems odd that obvious toxic effects on hives or brood has not been widely observed in the field, if at all.  At the same time, effectiveness in disease prevention has been commonly observed.  Something must be mitigating or buffering the dosage to individual larvae to optimal levels.

This, together with the questions as to amount, timing and methods of pesticide contact in the real world as well as bee age at the time of contact make for a very complex set of potential conditions.

Studies such as this attempt to isolate factors, but in doing so, should, IMO, be certain that the artificial conditions and situations presented and observed have some real-world meaning and are not outside the range of possibility.

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

Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm