> If I  have to bet I say that mites adapt faster to bees than bees to  mites.
> Why?  There is a lot more genetic variability with bees with multiple external mating by queens compared with brother:sister mating among  mites.

Resistance mechanisms are not driven solely by mating and the
resulting genetic recombination. Much evidence is building to prove
that organisms can develop heritable resistance as a response to
attack. This is in direct contradiction to classical models of
evolution and genetics. This field is rapidly changing and the concept
of epigenetic evolution is poised to explain a great deal we couldn't
before. The following refers to bacterial resistance to antibiotics
but it would no doubt apply to insect resistance to pesticides. I wish
I had time to boil it down a little, maybe someone else can do it.

QUOTED MATERIAL

We present data strongly supporting the conclusion
that evolution can occur without mutation. A
model to explain the observed evolution of antibiotic
resistance is illustrated. Within an isogenic population
of E. coli there is random variation in the expression
levels of genes, creating phenotypic variation.

Epigenetic variation shows an element of heritability. Some
cells with elevated expression of genes conferring antibiotic
resistance survive antibiotic selection, as do sufficient
progeny to allow colony formation.

The cells with increased expression of resistance genes in
turn show variation in expression levels, but now under
selection and therefore with sustained elevated levels,
allowing selection of still higher degrees of resistance.

Serial exposure to rising concentrations of antibiotic
results in cells with higher resistance than possible with a
single round of selection

It is interesting to note that many examples of
epigenetic inheritance between generations
have been reported in metazoans as well, including
paramutation in plants, the FAB-7 DNA element in
Drosophila, and RNA-mediated epigenetic inheritance
in the mouse. It is reasonable to suppose that
such mechanisms generating heritable phenotypic variation
could provide the substrate for the action of natural
selection.

-- 
Epigenetic inheritance based evolution of antibiotic resistance in bacteria
Mike Adam, et al
http://www.biomedcentral.com/1471-2148/8/52

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