What does it mean that target species don't get wiped out

patfoley patfoley at csus.edu
Fri May 28 16:02:17 EDT 1999


I can't tell whether Paul Ch. is joking or not about different effects of
pesticides on different species. I believe he is saying that Bt and
chemical pesticides are just as dangerous to all species of Lepidoptera
(and their predators?) as they are to Gypsy Moths, that is not
extinction-threatening.

If my interpretation is correct, then a rebuttal is barely necessary.
Anyone who has studied the ecology of anything knows that population
response to mortality varies incredibly across species. This is obvious to
naturalists and professors alike. Opportunistic species with no Allee
effect problems and flexible life cycles will usually be at much less risk
than their less flexible relatives.

The risk to some non-target species of Bt may be substantial, well worth
investigating. Moreover the certainty of artificially selecting for Bt
resistance in large populations of target-species is dismaying to many
involved in agriculture. A friend of mine told me recently that the secret
view in the pesticide industry is that serious Bt resistance is less than a
decade away. But by then they will already have made their money. I don't
mind about the money, I mind about the waste of a useful tool (Bt spray)
and the risk to many local populations of insects (there are thousands of
vulnerable lepidopteran species within range of corn and other engineered
plants, not just the Monarch).

I anticipate that the response to this note will be: So name a species that
has gone locally extinct due to pesticide use. Visit the cotton fields of
Northern Mexico. Read a little ecology. This is not just an opportunity for
rhetoric. Serious ecosystem and agricultural disruption is at stake here. 

Patrick Foley
patfoley at csus.edu

P.S. I drive a 1989 Mazda pickup, and I am not applying for any grants in
this area. My research is in population extinction theory. I do, mea culpa,
teach at a university.

 


More information about the Leps-l mailing list