I was very interested in Tom Culliney's information on toxicity of
fluvalinate (Hi, Tom!).  As most of you would be aware, fluvalinate is not
only used in Apistan; it is also an insecticide which is used in horticulture
and agriculture on a range of pests, including aphids, thrips, whitefly,
and leafroller.  It has a residual effect, while at the same time being "soft"
on many predator and pollinating insects.  It does, however, have a high
toxicity on predator mites.
 
In New Zealand, fluvalinate is approved for use on kiwifruit for leafroller,
up to and including flowering, but not after.  Because it is so "bee safe",
its use has greatly reduced bee kills during the early stages of pollination
of the crop (when adjacent orchards come into bloom at different times).
The Kiwifruit Pollination Association, a beekeepers' group in New
Zealand, recommends the chemical to kiwifruit growers.
 
The problem, though, is at the end of the bloom period.  Growers here
must use other, less "bee safe" insecticides at this time because (I have
been told) no tolerance levels have been established for fluvalinate on
food.  Since almost all New Zealand kiwifruit is exported, and chemical
residues of any kind are a major issue in maintaining access to overseas
markets, growers here are strictly audited to ensure that fluvalinate is
not applied after petal fall.
 
As a result,  because of the staggered bloom period between kiwifruit
orchards, we still experience bee deaths at the end of flowering. As you
can imagine, beekeepers in New Zealand would dearly love to have
fluvalinate registered for post-blossom on kiwifruit.
 
As Tom points out, fluvainate has  low mammalian acute toxicity (LD50 -
5150mg/kg oral, >2100mg/kg dermal) and no apparent oncogenic,
teratogenic, or adverse reproductive effects.  So the mystery is why
haven't tolerance levels been established for the chemical?  Does
anyone have any further information on why tolerance levels in foods
have not been established for fluvalinate?  Is it just a matter of the costs
involved in establishing such tolerances, or is there some other issue
involved?