>Can you comment on how other researchers compute efficacy and if there

> is an agreed method or if varying methods are used.


I've seen a number of methods--there are tradeoffs involved in all!  I'm
not sure that there is yet standardized agreement.  Juanse referred to the
Coloss Beebook, which discusses mite population estimation, but we will
have to wait for Beebook III for standardized methods for efficacy testing.

The book mentions that efficacy can vary depending upon season--I also
observe this.  Also may vary with temperature, colony size, proportion of
sealed brood, etc.

One can compare mite drops to see whether application of a miticide causes
increase mite mortality for x period of time, but this may not tell the
whole story.

One major issue is whether a treatment has a delayed effect.  For example,
if a treatment suppresses the mating success of mites, then one might not
see an immediate result, but would see a longer-term suppression of mite
levels.

Then the question is how to estimate the actual number of mites in a hive
at any time.  One can shake all the bees off all the combs and wash them.
 I've done this, but it is a waste of bees' lives, and tedious (even more
so if sugar shaking of the entire colony population is then performed).
 Then one must estimate the number of mites in the sealed brood, which is
difficult because the distribution is often so patchy.

Then there is the issue of direct vs indirect methods of measurement.
 We've been through this before, and we clearly disagree.  Any measurement
of mite fall is an indirect measurement, depending upon many variables, and
can vary greatly from day to day, despite the actual mite population or
infestation rate of the adult bees being relatively constant over the same
period.

 There are also potential problems if one uses a miticide to attempt to
cause all remaining mites in a hive to drop (a process that would take a
minimum of 13 days).  For example, in a protocol recently sent to me for
review, the researcher planned to use the same miticide for the clean up
drop (to determine remaining mites in the colonies) as the miticide being
tested, which I find fault with.

To me, the bottom line is to determine the final effect of any treatment
upon mite population growth over time.  I prefer to measure after at least
three mite reproductive cycles (about 51 days).


-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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