>However in the early 1990’s racemic fluvalinate was replaced with tau-fluvalinate (having a single form) resulting in a 2-fold increase in toxicity of this material to honey bees.

This statement has been widely repeated, but I'm not sure if it is
accurate.  I checked with the company rep, Doug VanGundy, and he
explained that the formulation was always the tau form, and that the
only change was in the label to recognize the fact.

Here's a funny fact lifted from my recent article in ABJ, on the
subject of fluvalinate:

Curiously, the author of the EPA registration of the product  did not
appear to understand just how Apistan strips were to be used, as
evidenced by the following paragraph:
“However, an appropriate label statement is required to protect
foraging honeybees when the LD50 is less than 11µg/bee.  For
tau-fluvalinate, the acute contact toxicity study to honeybees
indicates that the LD50 is 0.2µg/bee.  This classifies tau-fluvalinate
as highly toxic to honeybees.  The impregnated strip formulation
[Apistan] is used in beehives to treat Varroa mites when bees are not
present.”
Apparently the author was unable to entertain the notion that
beekeepers would actually put the product into a hive of live bees!

Randy Oliver

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