Assuming that breeding in worker cells is a simple recessive trait, at any
one time, 25% of the population would have the ability to do so, 50% carry
it as recessive, able to be passed on, and 25% not have the trait. Since
current studies don't show that high a rate of worker reproduction (that I
have read), let's say it is a combination of several genes that allow this
trait to manifest. That leads to a much smaller number of mites being able
to reproduce in the smaller cells (note that cell size is probably
irrelevant, the trait may be the ability to reproduce faster or to reproduce
on the different nutrition available from a worker vs a drone).  So long as
a large number of mites exist that were bred in drone cells, there are
plenty of the dominant genes around to suppress the recessive ones, as the
hive will probably collapse before "worker mites" become the only ones left
in the hive, unless treated.  With only worker mites around, the beekeeper
is more likely to not treat, so long as they monitor mite levels. Killing
off 50% of the mites, selected randomly amongs those carrying dominant
genes, would result in a temporary increase in the percentage with the
traits for worker brood reproduction, but would not necessarily affect
future generation's percentages in the long run.

We know that mites will reproduce at levels high enough to kill the colony
if left alone and that they will do so on hives using all standard
foundation. Adding a comb of drone foundation just makes available a larger
area for the mites to reproduce, unless you can guarantee that no other
drone brood is laid elsewhere. That would seem to require replacing any
combs that have had drones previously laid around the edges, as those cells
will be stretched out somewhat, leading to future use as drone cells as
well.

All of which leaves out the arguments of: reduction in hive strength due to
comb being dedicated for drone production (if you want to replace easily,
you go to 9 frames per box, now you are removing another from production of
workers, leaving only 8), reduction in productivity from continual opening
of the hive to remove the comb, the labor intensive costs and the effect on
your back of removing those honey supers on a regular basis so you can keep
pulling the drone comb all summer (unless you put "standard" comb back in
during all honey flows).

I think the beekeepers that do this see a positive result -- "I removed
mites from the hive, I can see them" -- and confuse this with overall mite
population reduction. The two are not necessarily the same.  Until there is
reproducable research that shows multi-year mite control with this method
(no chemicals, but other IPM methods allowed), while maintaining honey
production (although not necessarily at the same level as with chemical
methods), I believe it to be a waste of time as a means of "control".

Karen Oland

-----Original Message-----
From: Frank I. Reiter
Let's
assume that only 50% of the drone brood in a hive is killed, and with it the
mites that were growing in it.  Let's say for the sake of argument that at
that time, 1% of the mites in brood in this colony were in worker brood.  By
killing 50% of the drone brood mites, you've doubled the percentage of the
next generation of mites that was born from worker brood.  Now do that over
and over and over....

If one accepts as plausible the hypothesis that mites born from worker brood
are more likely than those born from drone brood to be able to lay their
eggs in worker brood, then you are selecting for that ability any time you
kill any quantity of drone brood without killing an equal quantity of worker
brood.  The higher the percentage of drone brood you kill, the more
aggressively you are breeding worker brood compatible mites, no?