Neonicotinoids under review.

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Queen Bee
Nov 8, 2008
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From a BEE-L thread.

From Eric Mussen's Newsletter

Neonicotinoids Under Review

This spring the California
Department of Pesticide Regulation (DPR)
decided to request more information on the
effects of the uses of the nitroguanidine
class of neonicotinoids. Specifically, they
wish to see information on imidacloprid,
clothianidin, thiamethoxam, and
dinotefuran. As you may know, imidacloprid is marketed by a very large
number of companies. Since the original
patent belonged to Bayer CropScience, their
company will be presenting data to cover the
other distributors. This review will cover
282 different pesticide products registered to
50 different registrants.

The decision to request this review
was based on an "adverse effects disclosure"
pertaining to imidacloprid. There were
twelve residue and two combination residue,
honey and bumble bee studies of imidaclo-
prid use on a number of ornamental plants.
The two triggering items were "high levels
of imidacloprid in leaves and blossoms of
treated plants, and increases in residue levels
over time."

The bits of data that were coming in
demonstrated that residues of imidacloprid
in the blossoms of treated trees could
exceed, in one case by twenty times, the
LC 50 for a honey bee, which is estimated to
be ? 185 ppb. An LC 50 is the lethal concen-
tration that would be expected to kill 50 of
100 bees consuming that dose.

The major concern relates to
pollinator exposure, so the following uses
were exempt from this examination:

1. gel or impregnated strips
2. termiticides
3. rodent flea control products (field)
4. pet spot applications
5. ant and cockroach baits
6. premise pest control
7. manufacturing use products.

DPR hopes to obtain residue
analyses on nectars and pollens of treated
agricultural crops that require pollination.
DPR also is going to require results from
studies designed to determine the
consequences of having residues in the diets
of various stages of honey bee development.

US EPA also has a review docket for
imidacloprid under way. In an attempt to
better ensure a "level playing field" for the
neonicotinoid class as a whole, EPA will be
looking at the rest of the neonicotinoids in
fiscal year 2012.

I have reviewed enough published
information on neonicotinoids and honey
bees to know that the findings are going to
come in many shades of gray, not in black
and white.