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synthetic pyrethroids

The whole subject of synthetic pyrethroids contains within it all the
subtleties and paradoxes inherent in the larger topic of pesticides.
Consider:

Pyrethrins, derived from the pyrethrum daisy, have been used to kill (or
often stun) insects for thousands of years.  One of my books said 10,000
years but my guess is it wasn't more than 9,500.

They can kill soft bodied insects like aphis but not dependably.  Often
they stun the insects, who fall to earth.  The hope is that they can't find
their way back into the plant.  Pyrethrins also suffer(or benefit depending
upon your point of view) from a lack of persistence;  they degrade within a
few hours, a little longer if it's foggy or overcast.

One of the interesting ironies of pyrethrins is that their mode of action
is almost identical to DDT.  The last time I did any reading on the subject
that was still a point of confusion amongst scientists.  DDT, of course,
had other characteristics that made it pesticida non grata-it is fat
soluble and extremely persistent(a benefit or liability depending upon your
point of view).

There's even another historical link between pyrethrins and DDT.  During
World War II, fearing a typhus epidemic in Italy, the Allies put together a
program to prevent the spread of the disease.  They used DDT, an ultra-new
compound at the time and pyrethrins plus a campaign of public sanitation
meant to cut down on the insect carriers.  GI's were dusted with
insecticides. The program worked wonderfully.  But to this day advocates
debate whether DDT was the elixir or the pyrethrins or simply the increased
vigilance and attention to sanitation.

Sometime after the war scientists began trying to synthesize pyrethrins to
avoid the obvious cost of growing, harvesting and extracting the active
ingredient.  Thus were born synthetic pyrethroids.  Except that the
molecular form of the synthetic was not exactly the same as the natural
product.

Which makes synthetic pyrethroids either organic or *not* organic depending
upon how you define the word.

They are also slightly different in efficacy.  They persist a bit longer,
sometimes for a few days.  They are more toxic to insects.  And they share
some of the downsides to most broad spectrum insecticides:  they
indiscriminately kill predaceous("good") insects and phytophagous("bad")
ones.  SP's reliably kill honey bees, for instance.  They also *can* kill
birds but it would take a concerted effort to actually do so.

Now imagine yourself working for the US Environmental Protection Agency in
the 1980's.  Public sentiment favors the elimination of numerous synthetic
insecticides from the market.  The Ames Test for carcinogenicity eliminates
some;  ecological damage eliminates some others(including, of course, DDT);
water contamination knocks out a couple.

But you need some kind of 'safe, effective' pesticide for things like
household pests(ants?).  What's left?  Pyrethrins are too weak and
ineffective to satisfy most consumers.

The answer was SP's.  Look at the shelf of any nursery/garden center in the
US and you will find that virtually every aerosol and RTU(ready-to-use) is
a synthetic pyrethroid.  Allethrin, Permethrin, Resmethrin, there are now
over a dozen SP's registered for use in the home in the US.  Many mix in
some pyrethrins, too.

I don't know of any granules or powders that are sold in California
nurseries but it sounds like this chalk product from Oakland's Chinatown
has a registration for ants.  IMO a chalk greatly increases human exposure
to the toxin.  Aerosols and RTU's would be gone quickly, the chalk's around
to blow up your nose for days or weeks.  But that expresses the point
exactly.  There are lots of ways to keep ants out of your house but they
are a hassle;  caulking, persistent spraying with insecticidal soaps,
destroying nests in the ground(when you can find them), diatomaceous earth.
But insecticides are easier and more convenient.

Are SP's a valid product for people with an environmental consciousness?
They are organic in the sense that they bio-degrade much as pyrethrins do.
They are non-persistent when compared with just about anything else you can
buy in the States.  The formulations used in the US are very dilute greatly
limiting the mammalian toxicity.  They are not carcinogens or
teratogens(birth defects) or mutagens.

OTOH, SP's *are* synthetic(and, therefore, not organic by California law).
They cause environmental damage by reducing populations of predaceous
insects.

But the name sounds organic, no?

Jerry Heverly, Oakland, CA
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