> The neonics are a big gray area not black & white.
>

If you substituted "pesticides" for neonics, I would agree.

A cursory search of "imidacloprid nectar" gives a number of studies that
address some of Kim's questions. As Peter said, there is plenty of data out
there. But they still do not answer the question of what, if anything, is
happening long term to the bees.

I realize I am on an "application" kick mainly becasue of Stan's comment on
soil injected effect on his bees compared to seed treated.

He also was concerned about the half life of Imid in the soil. I was not,
but that was based on seed treatment. I can understand his concern with
soil injection.

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114

Is a study on different application methods. Telling in the study is that
seed treatments "found mean concentrations from 2 to 3.9 ppb in pollen
[12]<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114#pone.0039114-Cutler1>
–[14]<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114#pone.0039114-Krupke1>and
from 2.2 ppb to 3.0 ppb in nectar
[12]<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114#pone.0039114-Cutler1>,
[13]<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114#pone.0039114-Bonmatin1>.
Two studies using radiolabeled imidacloprid applied to sunflower seed under
more controlled conditions found concentrations of 3.9 ppb in pollen and
1.9 ppb in nectar
[15]<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114#pone.0039114-Schmuck1>and
a concentration of 13±13 ppb (mean ± sd) in pollen "

Then they studied drip and soil "spray" and had very interesting results in
that they were inconsistent! In general nectar and pollen concentrations
were higher than seed treatments, but  they varied by year. In some cases
the concentrations were much higher (up to 30ppb) but in others they were
lower but still higher than seed treatments. The researchers did not know
why.

Add that "the highest rate we found for a seed treatment with imidacloprid,
for corn in Northern Europe - 95 g AI/ha,
[29]<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114#pone.0039114-Schnier1>,
was one-third the lowest labeled rate for soil application of imidacloprid
on squash, 281 g AI/ha
[30]<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039114#pone.0039114-CDMS1>and
27% of the lowest rate of imidacloprid used in this experiment (358 g
AI/ha)."

So application methods make a difference.

Plus, application amounts are different (as Stan noted) depending on the
crop.

Problem solved? No. In almost all cases the levels of Imid in nectar and
pollen were in the 10-15ppb area for other than seed treatments (2.5- 5x
higher than seed treatments). As Randy noted, that still is not a smoking
gun. But we are getting into the area of potential problems.

So where does that get us?

We know that there is a difference between seed treatments and other
application methods with seed treatments the most benign (benign is a
relative term since we are talking about pesticides). We also have valid
field observations with canola and other crops (like sunflowers) that are
seed treated and seem to have no effect on bees, and this is over a long
period. That is it. Beyond that is conjecture.

My guess is that this will settle out over amounts used in different
applications (other than seed treatments) and time of application. Even
then, I think that it will not come close to solving the problem and bee
deaths will continue to pesticides, and not the neonics alone as some
suggest.

I have learned a lot on this list about pesticide issues. Some thing
staggered me, the application of fungicides at bloom on almonds and
learning that the fungicide also has an "insect growth regulator" as a nice
add on. Just picture that being picked up in pollen and stored in hives to
be fed over a long period. Forget the neonics and their "cumulative effect"
when you have a colony dwindler stored in your hive right at the time of
maximum build-up for a successful year.

It would be interesting to see any correlation between almond growers and
beekeepers who lose colonies. One interesting comment in one of the many
"bees are all gone" documentaries was the observation about, I believe,
"Paramount" almond growers. That they are considered the most bee friendly
grower and bees seem to do well after pollination. They emphasize that they
do not spray anything during bloom.

That would make a revealing study: almond grower vs beekeeper success.

Bill Truesdell
Bath, Maine

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