>It seems like the quantity

> that affects us is the ratio of the half life of the miticide and the
> time between treatments?


You are exactly right Blair.  Could be back calculated from the
registrant's data on residues after one application, compared to residues
after multiple years.

Judging from comb analyses that I've seen, coumaphos and fluvalinate appear
to have very long half lives in beeswax.  Some comb analyses showed
surprisingly high residues of these products.

On the other hand, commercial beekeepers have used amitraz continually for
quite a few years.  Residues in their combs of DMPF currently run about 100
ppb (USDA 2012 survey).

I have the results at hand from a beekeeper's cell starter brood frame.
Amitraz and DMA were non detectable, DMPF was at 217 ppb.

The above results suggest that with repeated application, DMPF residues
could indeed build up.

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

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