The question on the table here on SANET is about
insecticides/miticides of the class Spinosad, and their use in
organic ag systems.
It seems to me that the discussion here is missing some important
points.A much greater tragedy than "undermining" a Dow product
(Chuck's concern) would be using it without full due consideration of
the bigger picture.
Mode of action
Spinosad is a neurotoxin (a nerve agent). Its mode of action is to
hyperexcite the nervous system of the arthropod that ingests or
touches it, until the creature perishes (rapidly). It is an
acetylcholine and nicotine activator. This MOA appears in Dow's own
materials on its Spinosad product, "Conserve."
Given that acetylcholine in nerve cells is highly conserved
evolutionarily (meaning it arose early in the history of life and is
shared by "higher" organisms), I'd think that the discussion of
neurotoxins in sustainable and organic ag systems would be somewhat
broader and more cautious than I've been reading here.
Spinosad is a new chemical class of insecticides, developed in the
90s, registered with the EPA for use in the past few years. Their
active ingredient is synthesized from /Saccharopolyspora spinosa/, a
rare actinomycete (an order of filamentous soil fungi that includes
various antibiotic-producing organisms).
Spinosyn A and spinosyn D are fermentation-produced metabolites of
Apparently in 1982 a vacationing scientist found this actinomycete in
the soil of a former rum distillery in the Caribbean. One is given to
guess that this scientist was prospecting for organisms, since it's
unlikely that it simply jumped in her/his suitcase on its own nor
that the scientist was poking around the old plant looking for a date
with Captain Morgan. I doubt anyone on that island will see royalties.
Dow developed the (legal term) "novel process" for synthesis, and it
claims the metabolites formulated as insecticides are biological pest
controls with the "punch" of a synthetic insecticide.
Biological control, IPM, impacts
That seems to me to take the concept of biological pest control a bit
far afield. If you have to pirate a rare organism from another nation
then involve the research and development resources of a
multinational agrochemical corporation in synthesizing metabolites
from it, I'd say that's stretching the term.
And where did this idea come from, that the idea of biocontrols is to
quickly and wholesale OBLITERATE "undesirable" species in an
agroecosystem? How is this more intelligent an approach to biosystem
management than offered by earlier generations of neurotoxin
pesticides? It is said that nature abhors a vacuum; once you create
such a vacuum, what will rush to fill it? What willl it require of
the manager, other than to keep spraying to maintain the vacuum?
Certain people consider Spinosad a good product for controlling
caterpillars, leafminers, leaf beetles, fruit flies, thrips, and
sawflies. It is fast-acting--organisms die in a day or two after
ingesting it or coming into contact with it, with no recovery. I
haven't been able to track down where it was tested or the protocols
yet, but it is said in many of the marketing materials, and
reiterated elsewhere, that Spinosad "does not significantly affect"
ladybugs, predatory mites, and green lacewings.
I haven't found anything about its impacts on, say, the /Collembola/
(the countless members of thousands of species of tiny wingless
insects so crucial for healthy soil). Do we now define as
"sustainable" those systems whose soil arthropods have been
obliterated? Do we now define as "sustainable" any system that has a
few ladybugs and lacewings running around topside, while the soil has
been purged of all but a few desirable mite species?
The impact on mammals, birds, and predatory beneficials is reported
as "very low," but I'm guessing this refers to the toxicologically
defined impact, which can overlook many serious/crucial biological
I'd be interested in hearing about research on this aspect of
Spinosad formulations. Until I see that, my assumption is that the
manufacturer did the LD/LC research sufficient to get the product
approved by the EPA.
My first question upon reading the marketing materials for these
pesticides (which includes nearly all information you find at the
nursery and on the Web) is, how can Spinosad/spinosyns distinguish
between a "pest" caterpillar and, say, the caterpillar of a native
It affects nicotine and acetylcholine, and so unless these toxins can
discern species, anyone with nerve cells, of any species, is going to
be affected somehow if they ingest or absorb it. What forms will
those neurological effects take, when they are not overtly,
statistically significantly "lethal"? (Like hyperactivity, confusion,
aggression, or disabled focus.)
My second question involves impact on other species. The LC50 for
honey bees is reported at around 12 ppm, and thus the label
discourages applications "where bees are foraging." Tell me please,
where are bees are NOT foraging? Far as I can tell, they're
everywhere flowers are, when there are flowers. The last thing that
the remaining, highly stressed populations of these humble
pollinators need at this point is more people spraying them dead. Or
messing with their ability to navigate, communicate complex
information like food locales, or calmly, cooperatively work in their
Spraying at night is an easy out, yet the half-life of the Conserve
formulation of Spinosad is given in the manufacturer's information as
up to fourteen days. What this says to me is that there can be
effective residues for easily a month.
Third, since applications include tree fruits, cotton, nuts, and
vegetables, I'd certainly like to know what effects (food) residues
have on mammalian systems at different times of year (since
U-distributed low-dose biological effects in mammals seem to relate
to season), alone and in combination with other chemicals.
Finally, I have serious questions about the evolutionary effects of
taking a novel soil organism restricted to one small part of the
world and synthesizing it into compounds to distribute and use widely
as biocides. Isn't this, basically, the situation humans now face
with antibiotics (synthesized from common soil organisms)? I'll say
more below about the antibiotics angle. In brief, Spinosad strikes me
as a novel antibiotic--one that targets not other microbes, but
"higher" organisms (things with neurons).
For anyone who hasn't awakened to the population dynamics of the
antibiotics issue yet, read anything by the public health journalist
Laurie Garrett, and a dip into Jared Diamond's work wouldn't hurt
Thoughts on the marketing
Dow is clearly marketing their Spinosad formulations to people who
want to kill, and kill fast and big--none of this wussy biological
stuff that takes time and attention. But what about the fact that a
system cleared of certain arthropods is now a vacuum for others?
Sounds to me like a prescription for constant spraying.
I read, in the mid-90s, one of the resident nozzleheads at the
UW-Madison, who wrote in a newsletter, "[The spinosyns have] low
mammalian toxicity and low nontarget toxicity that, combined with
relatively low use rates, should result in minimal safety concerns."
My first thought was, "relatively low use rates"? What does that
mean? Ten times a year? Twelve? Two?
Dow is also marketing Spinosad formulations for residential lawn care
and golf courses. Residential lawns already use 10 times per acre the
pesticides of farms. One of the selling points of Dow's "Conserve" is
that it doesn't leave a nasty old visible (clay) residue. So your
kids can crawl in it, and you won't even see it. Contact neurotoxins
you can't easily detect? That's progress?
In its marketing materials, Dow repeatedly compares Spinosad to Bt.
My guess is that this is an effort to put their synthesized
neurotoxic metabolites on the same level--in consumers' minds--as the
highly trusted perennial friend of organic gardeners everywhere, Bt,
an actual organism (spore).
Bt formulations contain the organism itself, not ingredients
synthesized via anaerobic breakdown by other organisms in a
proprietary, undisclosed process. Bt is highly selective in its MOA
and target organisms. Yet in this way it is possible to build on
existing consumer trust in and market for an organic-approved
product, while eroding clear thinking about and observation of the
natural history of what's unfolding with the new product. All you
have to do is fling some stuff around about "resistance management,"
and, what, all other critical thinking ceases?
And PR (advertising posing as news or science) gets around. Here's a
concatenation of truth, ignorance, confusion, and poor grammar from
the Home and Garden Television Network. It starts off with
misinformation and never gets better:
Saccharopolyspora spinosa is a biological control
made from a fermenting process. Used to control a wide
range of leaf-eating insects such as caterpillars, sawfly
larvae, thrips, Colorado potato beetles and fire ants, this
insecticide attacks the insects' nervous system,
causing paralysis within one hour. And even better,
Saccharopolyspora spinosa is not harmful to beneficial
bugs in any way. Mix Saccharopolyspora spinosa with
water and spray the solution to plant foliage.
SOURCE: Gardening by the Yard, episode GBY-709, "All Natural Pesticides"
I've heard similar misinformation and confusion in the aisles of
various nurseries/garden shops where I eavesdrop. And the catalog of
Gardens Alive! repeats the drumbeat that spinosyns are like Bt.
Well, yeah, and a dog is like an umbrella if you hold it over your
head and push its ribs out far enough on a rainy day. Organisms and
synthesized metabolites are not the same thing, unless we've decided
to do away with sense altogether.
If Spinosad is like anything, it's like antibiotics--microbial
suppressants derived from soil organisms. Except that Spinosad
formulations "higher" organisms, organisms that have, as we do,
On organic farms
In my mind this all would raise serious questions for Spinosad's use
on organic farms. I won't use this stuff here. I can't afford organic
certification, but if I could, I wouldn't, not even if the cutworms
were carrying the house away. (Which in fact is the slugs' job.)
Even beyond the concerns I've listed above, I'd hate to be in the
pickle of having to suppress my or others' later observation or
research on the effects of Spinosad formulations, because
observing/admitting these effects would give the PR arm of some
multinational agrochemical company an example with which to discredit
organic standards. "Well, they certified the stuff for use! And they
were wrong! See? It's *all* hogwash! The standards mean nothing!"
Not that that isn't already happening in the Empire of the Least
I was under the impression that at least one Spinosad formulation,
Entrust 80 WP, meets the USDA/NOP organic standards. I thought its
approval for use came out of a consideration of its inerts, not its
When some of us got in this gig, in Ancient Tymes when Ford was
pardoning Nixon, the idea was to farm without things like
neurotoxins. Not how to develop ones whose impacts could be
justified so long as they were better than earlier ones, or you
didn't look at certain other difficult stuff.
There are no incentives I know of for finding out that one's huge R&D
project is not cost effective when balanced against actual effects
(rather than the far simpler test, risk of lethal dose). A pesticide
product that combines shock-and-awe with the feel-good qualities of
organics probably tests pretty well in the focus groups, and that
would be incentive enough.
Thanks for listening.
Home office: 360-459-5683
Home office fax: Same as above, phone first for enabling
The First Rule of Holes is that when you are in one,
you should stop digging. --Molly Ivins
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