> Chiesa (1991) was able to control V. jacobsoni in honey bee colonies with
> thymol without noticeable damage to the colonies at temperatures ranging
> from 5 to 9 C (41-48 F). However, Gal et al. (1992) found thymol
> applications deleterious to bees when temperatures reached 27-28 C (80-82
> F).
I have used thymol crystals at 30C without problems (but not often - 30C is
unusual here), but it should be remembered that I have fully open mesh
floors.
With lower temperatures I find that thymol works well in colonies with
plenty of brood, but is much slower to evaporate (or deliquesce) in colonies
with little brood. This is very noticeable with our bees (A.m.m.) as poor
weather in July can cause queens to go off lay temporarily. We seem to have
no problems using thymol on colonies returning from the heather moors in
September when the weather can be much cooler - these colonies normally
return with large areas of brood after the stimulation of working heather.
So in my view it is the warmth from the brood that makes all the difference.
Have researchers considered the varying effects of mesh floors, amount of
brood and the sub-species of bee?
Best wishes
Peter
***********************************************
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