>
> >His comment  "mite treatments that kill a high percentage of mites,  lead
> to
> the mites building up restiance faster than a treatments that kills a
> smaller percentage."


Dennis was absolutely correct.  There are likely always a few resistant
mites in any population, or ones randomly occurring due to mutation.  Such
a mutation has a strong chance of being passed to her daughters due to
brother/daughter haploid/diploid mating.

An important point is that there is usually a cost in fitness for a mite to
have resistance to a miticide.

Let's look at the extremes Charlie.  If a treatment kills only 5% of the
mites, then there would be virtually no selective pressure for the
population to become resistant.

On the other hand, if the treatment kills 99% of the mites, there would be
STRONG selective pressure.  That 1% would have no competition, nor
outbreeding to dilute the trait.  Without competition, the offspring from a
single resistant female, in an environment where the treatment was applied
to all hives in an area twice a season would quickly dominate the entire
population, spread by robbing and truck transportation.  It only takes one
single resistant mite to do so, coupled with strong selective pressure
applied by beekeepers.

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

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