Hi Everyone,

>I think my post commented on an understanding I have that when V.D.
becomes
>resistant to fluvalinate it is only a very short step to resistance
to
>amitraz.  (If I didn't say that, that is what I meant to say.)
>
>What say you, Zachary?

Lloyd,
This is quite possible, but perhaps not because the two chemicals are
in the
same class (they are not), but because of generalized increase of
detoxification enzymes available (see my post today re three
scenarios).

One of them is that amitraz might have been used for a quite awhile in
US.

Zachary Huang


One thing I have not seen mentioned here is that amitraz is a synergist
for pyrethiods.  This clearly suggests that there is an interaction
between the two classes and pyrethoid resistance very likely includes at
least partial resistance to amitraz.  This would explain the appearance
of amitraz resistance along with the spread of pyrethoid resistance in
North America and Europe.
Another thing I have not seem much in this discussion is that one
cannot easily switch away from a treatment that bioaccomulates in the
beeswax so in most cases the mites are being exposed to fluvalinate and
coumaphos at the same time - lower levels of fluvalinate but it is still
there in the hive environment to continue to select for resistance.
This is a clear advantage of treatments that don't accomulate in the wax
- there is a time between treatments that the mite population is not
being exposed to the treatment.  Yes this allows the mite population to
rebound more quickly but it also greatly reduces the selection for
resistance thereby slowing the appearance of resistance.

FWIW

blane


******************************************
Blane White
MN Dept of Agriculture
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