Ron Bogansky said:" Dewey Caron reported that resistant colonies that were
then treated
> with Check-Mite had the greatest level of mite kill in the first 2-3
> days of application. I realize that the idea of treatment length is
> to get at mites that are still in brood cells when they emerge.

> why not use the strip for a shorter period of time killing most of
> the mites and knowing that there will still be some infestation,
> but reduced?  This could be timed with a period of minimal brood
> production".

There seem to be 2 points to remember:
1 In his classic study in 1987,  Ritter split colonies into an artificial
swarm and a parent.  He found 47-92
mites in the swarms and 2500 to 2900 mites in the old brod nests. So killing
out phoretic mites at a time when there is any sealed brood would be very
ineffecive.
2  When I apply miticides are applied to artificial swarms (part of my
standard method for managing my Long Deep hives)  the drop does virtually
cease after 3 days.  The strips could come out, but I leave them for 3 weeks
before transfering them to the (queenless) 'parent ' end of the hive, where
all the sealed brood has now emerged.  This is against the manufactuer's
guidance to leave in for 6 weeks and makes me uneasy.  The standard guidance
assumes a colony with brood. I have tried to get guidance from Vita and from
DEFRA on how strips should be used with broodless swarms but no deal.  The
additional testing is not worthwhile - so we are on our own.  The point to
consider is that while +% of mites will drop early, it is those who have
developed some degree of resistance (maybe a thicker cuticle) that get only
a sub-lethal dose. Given longer exposure , they might drop.  So shortening
the exposure time, even though mite drop has ceased, may accelerate the
development of resitance.  If however resistance has already been developed
due to groos abuse by only one beekeeper (as in UK) and the spread of fully
resistant mites in inevitable, is there any point in still being so careful?
I frankly do not know - but to use 2 sets of strips for a divided hive would
certainly double the price.

Jim has asked: "Once one starts doing things like making up one's own
pesticide label
instructions, where does it all end?"   Unhappily, we can guess, based on
experience of everyone dreaming up their own varooa poisons without
sufficent knowledge of biology.  Dead colonies, contamination of comb, a
growing reputation for beekeepers as a dangerous lot of idiots.
Manufacturers have been required to test their products fully - we can
expect to get the claimed results.
only if we use products  in accordance with instructions.  The problem
arises however if the instructions don't apply to the particular
circumstances. What if the label says: apply a splint before binding up the
wound - and u are in the midst of a desert of sand?  Difficult one.

Robin Dartington

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