>
>    It shouldn't surprise anyone that selection of bees for tracheal mite
>    resistance, in its detail, is not as simple as indicated>
 
>    We did several generations of selection (using the new bee mark and
>    retrieve method) and crossing in isolated yards, then tested the results
>    on a whole colony basis. (The simultaneous introduction controls to a
>    great extent, for Jerry Bromenshenk's concern about variation in time of
>    year: the host colony is what it is, for all lines. Ranking indicates a
>    difference in the line's susceptibility).
 
 
 That was an important test.
>    The mites in the host colony had a great choice in bees to infest, a
>    real smorgasbord. If a particular line was slightly unattractive, it
>    might be ignored (suggesting high resistance). In an individual colony,
>    however, mites don't have such a choice. (You might never eat mutton and
>    brussels sprouts at a smorgasbord, but you wouldn't go hungry if they
>    were all you had.. OK you get the point. I lost my appetite too).
>    Our observations of the correlation of "resistant" ranking of marked
>    bees, and relatively low mite populations in colonies, indicated that it
>    was a good measure. (Medhat Nasr did a larger test in Ontario and found
>    the same thing).
>
>    We haven't had the problem of great variability of tracheal mite
>    populations mentioned by Dr. Bromenshenk. Generally mite counts in
>    specific colonies changed on a trend which could be measured (and
>    distinguished bewteen colonies>
 
As per usual, Kerry has good information to convey.  His comment that
they went from monthly to 2 month surveys prompts me to say you will get
a much better idea of the dynamics of the mite by spacing out the surveys.
 
Also, if you do find resistance, mite levels should stay lower, and the
oscillations we saw should not be as great.  But I'm not talking about
resistant bees - far from it.  And, lots of folks in the NW thought they
had taken their hits and now had resistant bees, but the T-mite counts
over the last two winters indicates that is not the case.
 
The enormous swings we see were in our bees, Tucson bees, and you can see
the same in several published literature reports if you go to the raw
data and plot it.
 
So, I'm not convinced that one point in time surveys are of any use
unless you know you have resistant bees.  And, I think we really do have
more than one type of mite, but that's hard to prove.  Are your resistant
bees resistant to different strains of mite, or only to the one(s) in
your area?
 
Cheers
 
Jerry Bromenshenk
[log in to unmask]