> Right, in fall that might not be too high, but in early spring a hive with
a level like that might have a difficult time building up. I don't know how
many of those 12% (approx 2400 mites) would still be there in spring.

I guess we don't know that and personally I would not be comfortable with
that high a level in many hives.

> What would be high level in March? What about April? Without figures to
compare how can one say it is high or low? Is 12% high in Spring, or can you
skip a Spring treatment with this level?

Currie did work on this in Manitoba.  Once there is a significant amount of
brood, the 12% phoretic measured in the broodless period becomes about 2%
phoretic, apparently.  (I am deducing that from the fact that 2% in
september has been shown to be 12% at the end of October after all the brood
hatches) Adony is not entirely satisfied with this and thinks we need to
replicate the work here in Alberta on a larger scale to try to narrow down
the thresholds.

> You detected zero mites. We assume that there are mites, though, but we
don't have any idea how many, right?

Yes, but I have a very good idea from previous tests and I have posted the
details here in this thread, and the parent threads.  We did drops at
various times throughout the past year and think we have a pretty good
handle on the levels.  They are much lower than we would have anticipated,
and that is one reason we went looking for resistant mites in this last
pass.

> I would think 12% would be a pretty high level in April and would warrant
some sort of Spring treatment to prevent a crash in mid-summer. I had one
yard of 16 that was not treated all year (2001). August levels were 2 to 30
( approx. 1 to 10%). By October, they all crashed. Not one was strong enough
to winter.

Absolutely.  12% phoretic with brood in the hive is well above our
threshold.  Frankly, we don't like to see more than 100 mites in even one
hive in a yard when doing a 24 hour Apistan drop. (But we have sometimes --
apparently with no ill effect).

> IPM is *not* wait until they get till 50% and then treat.

Again, we have different persectives.  You are thinking about individual
hives, we are thinking about individual yards.  In 2,400 hives one or two or
100 individual hives (think hot spots) might get to that level due to errors
in treatment, susceptibility,  or other factors without putting the whole
outfit at risk or even justifying immediate action.  However, if we are
aware of this, we are likely to initiate action.

> IPM (as I have been taught it) is about determining safe levels of pests
and treating with whatever means necessary if these levels are exceeded.

That is exactly what we are doing.

allen
http://www.internode.net/honeybee/diary/