"Obviously this can be a problem with any treatment but just how many OA (sublimation) treatments are the bees likely to tolerate? "

I have seen claims that only one treatment is acceptable as more will damage the bees.  And, other claims that many are fine.  The best actual data I have seen was provided on Bee Source a year ago.  An individual had a hive with sky high mite counts.  He did an OAV and dropped a thousand or two.  He counted every single mite dropped.  He repeated after a few days and dropped about the same number.  To make a long story short he hit that hive with OAV until the mite drops finally came down.  It took something like 12 treatments!  This was in the fall.  Sept/Oct if I remember.  I am doing this from memory so do not quote my numbers.  If you want solid numbers go do a search and find his posts.  I do not know if the colony survived the winter or not.  But, he saw no obvious negative effects from all those treatments.

In my experience I would not expect the hive to survive the winter.  When I have treated high mite counts it took a good two months after full treatment with apivar was finished for DWV symptoms to go away.  So, even thou he got the mite counts down I would still expect residual viruses to kill the hive by spring.

I am also interested in Nancy's experience this year with EFB.  Are mites weakening the bees enough to allow EFB to be a bigger problem than in the past?  I have had EFB in from 5% to 20% of my nucs every year for the last four years now.  At the time I make nucs the colonies I use to make the nucs are pretty near zero in terms of mites.  I hear lots of people who say they have never seen EFB even once.  With only one exception it has always been in nucs for me.  But, this year I had one production hive that had it.  Is it an issue of queen genetics?  It has been shown that requeening a EFB hive with Minnesota Hygienic bees will not stop the problem and I run MH queens.  Are they particularly prone to EFB?  Nancy's experience sounds a lot like what I have been seeing.  I have found terra highly effective and if I treat with terra per the label I do not see the problem come back that year in that nuc.  So, it is easy to deal with at least until I run out of terra formulated for bees.

Dick

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