Hi Joe,
I understand the limitations of mite drop counts.  However, in this study, 
the only measured variable was mite drop.  So why measure it if you're going
to discount it?

A higher mite drop every year for four years in a row means more mites.
What some seem to be missing is that the author counted mite drops while he 
treated with Apistan.  Unfortunately, he didn't count for a full brood 
cycle, which would have gotten most of the mites in the colony.  His counts 
weren't an illustration of the bees cleaning out the mites due to small 
cell--it was an approximate measure of the mite infestation level at the end 
of the season!

Clearly, in this study his small cell colonies built up more mites each 
year.

However, upon looking at the data again, the 2006 counts do imply that small 
cell may have suppressed mite buildup somewhat.  Even though there were more 
mites in the SC colonies, they hadn't received an apistan treatment the year 
before.  Again, I'm not discounting an effect due to small cell, but this 
study doesn't really tell us much, other than that his SC group had higher 
mite levels each time he dropped the phoretic mites off with Apistan.

>This lengthening of the phoretic period, (arguably the highest risk period 
>for varroa)
Data by Martin and others would not support this.  Phoretic varroa have very 
low mortality.  Mites emerging with bees have extremely high mortality.


> Relying on mite counts alone  IMHO is a failure to properly
assess a colony, which is of course (as we all know) should be based
on ’over all performance’.
The point I'd like to make is that the bees that can tolerate mites (Apis 
cerana and the Africans) rarely allow the mite level to exceed a 2% 
infestation on the adult bees.  So depending upon the type of mite counts 
one makes (see my article in ABJ on comparison of various sampling methods), 
or at randyoliver.com), this level does have significance.  Colonies with 
very high mite levels are time bombs waiting for viruses to explode.

And Dee, I do understand about high mite drops in Sept being normal--I made 
that clear in my article on mite population dynamics.  However, in this 
experiment, the drops were not natural, they were accelerated by Apistan.


> culling colonies based on mite drop could perhaps be a selection against 
> two of
the known mechanisms for mite resistance; grooming behavior and brood
attractiveness.
I suggest that selection of breeder queens be made on performance first, and 
mite level second.  By mite level, I don't necessarily mean natural mite 
drop, unless you know how to interpret mite drop based upon seasonality. 
Far better to use accelerated mite drop with powdered sugar or oxalic, about 
mid August, in order to find which colonies allowed the smallest mite build 
up during the season, by whatever mechanisms.

By the way, did I ever tell you that I measured the cell sizes of the last 
feral that I picked up?  They ranged from 4.7 to 5.4 for worker cells.  The 
pupae in the smaller cells looked tiny!

Randy Oliver 

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