I apologize if this has already made the complete rounds, but I couldn't
find a satisfying resolution in the archives, nor from the most recent
thread on this substance.
Spinosad is an insecticide from Dow Chemical that is approved as USDA
Organic. The old trade name was "Success" and the new one reformulated for
USDA organic certification is "Entrust Naturalyte." It is highly toxic to
bees and is for use on fruit and vegetable crops. However, the Dow
literature as well as the product label state that the product poses no harm
to bees if allowed to dry on the applied area.
Some searching reveals that there are two pieces of research that Dow used
to make the above assertion to the USDA during petitioning and on their
product label:
1. Mayer & Lunden, Effects of "Success" on Honey Bee Forging and Mortality
When Applied to Blooming Apples, Proceedings of the Western Orchard Pest &
Disease Management Conference, 1998 (I have a copy of this that I cannot
redistribute due to copyright restrictions)
2. Bisbari, Mayer & Bret, Determining Re-entry Intervals for Pollinators
Following Spinosad Applications, Proceedings of the Western Orchard Pest &
Disease Management Conference, 2000
(http://entomology.tfrec.wsu.edu/wopdmc/2000PDF/4-CHEMICAL/Chemical%2000-9.p
df)
The former comprises one study and the latter comprises four separate
studies. All used Todd dead bee traps and forager counts per time per area
to assess mortality and morbidity during time intervals before and after
they applied the insecticide in to nearby Apple, almond, citrus and alfalfa
in bloom. Of the five studies in total, if accurate, four show that
nighttime application of Spinosad results in insignificant mortality in bees
that return to the hive after foraging treated crops, and insignificant
brood reduction after 10 days. One of the five studies demonstrates a
daytime three-hour drying period with similar results. They also applied
Sevin, a "conventional" pesticide to a control field as a positive standard,
with significant mortality after application.
My questions for this list are:
- Are any of you familiar with Todd dead bee traps? Information on the web
is sketchy and I have never had to count my dead bees that carefully. As
far as you can tell, were these reliably designed experiments?
- Wouldn't conditions have to be just right to be certain of sufficient
drying to not kill bees? What if it is cloudy, or a little cool? What if
the insecticide goes back into solution with morning dew or a light rain?
The Dow literature indicates the product remains potent in solution for a
long time (hundreds of days). It seems to me the experiments chose optimal
conditions for showing that Spinosad is harmless, and that many potential
conditions exist in the real world in which this product would be deadly for
bees in the application area.
- The product label for "Entrust" (http://www.cdms.net/ldat/ld62B023.pdf)
doesn't even mention nighttime application, instead suggesting the
three-hour drying period to avoid affecting bees.
Any other thoughts on the diligence of the research and nature of this
product? Doesn't agriculture like this just lead to pest resistance anyway?
Jeremiah Wilton
Seattle, WA
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