>In a given hive bees have 1 to a dozen  or so different sets of genes
>(depending on how many males the queen mated from) and the length of
> the generation before a new set of genes is created is 1 to 2 years.  With
>mites you can easily have several hundred different sets and the
>generation is 1-2 months.

Oh, why not...let's wade in.  This is in general true, but we must remember that neither North American honey bees nor North American mites have had the luxury of large founding populations.  Both have undergone what in genetics is termed a genetic bottleneck (the amount of genetic variation in the founding population is less than what was in the parental population, due to imports either intentional or unintentional, of a very limited amount of their native gene pool).  Therefore you can have 3 billion mites or bees that are genetically nearly the same due to sahred ancestry, and their effective population size is much smaller than their census population size.  Absolute numbers mean little unless the genetic variability of the organism is considered (which is why we have inbreeding problems in zoos for instance).  Because more bees have probably been imported than mites, bees may actually have a larger gene pool than the mites do.  (I am only speculating, I don't *know* whether or not the mites came from multiple introductions.)

Now, it *is* true that the mite undergoes many more individual generations than do bees, but what is more important is that both the bees and beekeepers are imposing very strong selective forces on the mites, and whichever set of genes survives our selection pressure is passed on to succeeding mite generations.  Basically speaking, by coddling our bees or any other monocultured 'crop' and trying to stave off their pests for them, we are reducing the selection pressure on the crop and increasing it on its pest.  In the end, if the pest is not eradicated, those genes in its gene pool that confer an advantage against our selection pressure will spread to all pest populations (of the same species) very quickly, while the genes that may be present in our crop that protect against the pest never have a chance to really become dominant, because the benefit of their presence is not allowed to be fully expressed.  So, the mites have the ability to evolve more rapidly, by nature of their short generation time and our selection pressures on them, but their currently probably very limited gene pool will retard that evolution until genes or gene complexes that confer an advantage are created through mutation, recombination or other genetic phenomena.  If those genes are already present, though, they will spread rapidly.

This is on purpose very simplistic, and anybody wanting to pick a fight over it, or wanting elaboration, please email me directly.

Martin Damus