OK, I'm still going through the paper.

From the paper: "1 ul of coumaphos (2 ug/ul)or τ-fluvalinate (3 ug/ul) in
acetone (or acetone alone for controls) was applied to the dorsal thorax of
each bee"

So the bees received topical doses of either 2 ug coumaphos or 3 ug
fluvalinate.  So how do those doses compare to actual in-hive doses if one
were to use CheckMite or Apistan strips?

Reed Johnson (2009) states:
"But how realistic are the dosages we used in this lab experiment? How
likely is it that a bee will contact enough of either compound from
Checkmite+ or Apistan strips to cause death? While real insight into this
problem would require chemical analysis of the bees, it is possible to get
an idea of the bees' exposure with a few calculations. Each Checkmite+
strip contains about 1.4 grams of coumaphos. Assuming that 10% of the
coumaphos present in the strip escapes from two strips in a hive of 20,000
bees over six weeks, that works out to a daily dose of 330 nanograms of
coumaphos per bee - enough to double the toxicity of tau-fluvalinate. If
similar assumptions are made about a pair of Apistan strips (each
containing 0.7 grams of tau-fluvalinate) in a similar hive for 8 weeks,
each bee would receive a daily dose of 125 nanograms - a dose insufficient
to change the toxicity of coumaphos."

So by Dr. Johnson's estimate, the researchers applied the products at about
10x the expected rate.  But even Dr. Johnson's estimate may have greatly
overestimated the field-realistic dose.  Cabras found that nowhere near 10%
of fluvalinate is actually released.  Cabras (1997)  Fluvalinate content of
Apistan(R) strips during treatment and efficacy in colonies containing sealed
worker brood.

One would expect that the companies that developed the products, or at
least bee researchers, would have simply measured the concentrations of
these miticides in the bees during treatment!  Pete, or anyone, do you have
any refs?

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

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