James Fischer wrote:

> To me, it seems that it is not a question of "if" one should
> treat a colony, but instead, a question of "when", except in
> the unique and rare case of no detectable varroa at all.
> Clearly, the worst-case economic impact for a honey producer
> would be to not only spend money on treatment, but also be
> forced to pull a colony out of production to do so.

I hope I understand the question, so if I am far afield, please correct me.

"Economic threshold" is covered fairly well at
http://instruct1.cit.cornell.edu/courses/ipm444/test/NotesThreshold.htm

It is interesting that the term seems to be interpreted differently and
is not consistent. I did some searching and that was the article that
seemed to draw together the complexity of the issue of "economic threshold".

Most IPM applications I have seen are to not just treat the affected
field but to trigger application of pesticide to the entire crop. That
makes the system economical, since labor is generally the larger cost in
most enterprises.

So if you hit whatever threshold, it makes sense to apply the treatment
uniformly and not discretely to each section of a field, even though the
rest of the field may not be as infected with pests.

Generally, IPM uses limited samples to trigger response to a pest. It
can give skewed results, since the sample may not be uniform, so it
makes sense to treat all the crop. You do not want to come back over and
over again just to treat each affected area in turn.

Same with bees. In a large operation it would seem to make more sense
with limited sampling to treat all the colonies rather than discrete
colonies, unless you can show that there is no Varroa in a colony, which
is difficult.

One of the few things I learned from a statistics class was when one
fluorescent bulb went out in a factory (at about its normal life), it
was more cost efficient to replace them all than just the one, since the
others would be going out also. That way, you would do the same thing
the next time and actually be more cost efficient than a piecemeal
approach. Again, labor is the driving factor, not the cost of the bulb.

Bill Truesdell
Bath, Maine

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
-- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and  other info ---
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::