Breakthrough in Pest Control?

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There’s a new article out about a new breakthrough in controlling pesticide resistant insects in Australia, one which involes trying to shut down their ability to resist pesticides:

Australian and British scientists have achieved a technical breakthrough to help control insects that have developed resistance to common agricultural pesticides, the New South Wales state government said on Thursday.

[…]

“Developed by the NSW Department of Primary Industries and Rothamsted Research in the UK, the technique relies on the use of naturally occurring enzyme inhibitors to disarm an insect’s defense system,” Macdonald said.

“The enzyme inhibitor acts first to shut down an insect’s resistance mechanisms. A few hours later, while the bug’s defenses are still low, the pesticide kicks in.”

I haven’t read the primary literature on this yet, so I don’t even know what enzyme they’re talking about. But I’ll just treat everyone to a couple of excerpts from Johnathan Weiner’s The Beak of the Finch so as to ponder the significance of this “breakthrough”.

In 1967, a distinguished entomologist announced in Scientific American the discovery of a “resistance proof” family of insecticides. The poisons were variants of some of the insects’ hormones. How could insects escape their own hormones? Yet within five years, flies had evolved one-hundred-fold resistance.

“This seemed to surprise people,” says Taylor. “It would not have surprised an evolutionary biologist. But it surprised pesticide sprayers and the manufacturers of chemical compounds endlessly.”

“If you look through the literature.” says Linda Hall of Cornell University, who specializes in the study of pesticide resistance, “you’ll find people saying, ‘Resistance will not develop for pyrethroids.’ That was incredibly naive. Almost anything you give an insect, almost any way you find to kill it, it will find a way not to be killed. That’s the whole bit of evolution: no matter what you choose for your killing method, it will find a way not to be killed. Yet people from various companies were standing up at American Chemical Society meetings and saying, ‘Insects should not develop resistance to pyrethroids.’ I don’t know,” she says. “I don’t understand it at all.”

Before human beings had heaped up a mountain of pesticides in the 1940s, when we were still in the foothills of this evolutionary adventure, farmers in the United States were losing about 7 percent of their crops to insects. During the blitz of the 1970s and 1980s the insects did not lose ground. Instead they nearly doubled their share to 13 percent. “Indeed,” note the ecologists Robert May and Andrew Dobson, “the fraction of all crops lost to pests in the United States today has changed little from that medieval Europe, where it was said that of every three grains grown, one was lost to pests… leaving one for next year’s seed and one to eat.”

So as we can see, this is not the first breakthrough in pesticide technology that was billed as the solution to our resistance woes. And given that we’re talking about an enzyme inhibitor here – a very simple thing to evolve resistance to, given that it requires only a change in an amino acid or two to sharply decrease binding afinity – I’ll give it about a month or two before insect populations are fully resistant.

5 Comments

the United States were losing about 7 percent of their crops to insects. During the blitz of the 1970s and 1980s the insects did not lose ground. Instead they nearly doubled their share to 13 percent. “Indeed,” note the ecologists Robert May and Andrew Dobson, “the fraction of all crops lost to pests in the United States today has changed little from that medieval Europe, where it was said that of every three grains grown, one was lost to pests … leaving one for next year’s seed and one to eat.”

That’s LAUGHABLE.

7%? Comparable to medieval times? Are they joking?

Before pesticides, ENTIRE COUNTRIES’ harvets were sometimes wiped out. This article makes it sound like farmers said “Hmmm, let’s spend billions of dollars for 70 years even though it actually increases loss to pests.” Ridiculous.

I’ll give it about a month or two before insect populations are fully resistant.

You seem to be giving the insects a very rapid reproduction rate. For most species, you wouldn’t even get a single generation in, much less enough for the new insecticide to exert its selective pressure.

Of course, your main point is otherwise sound.

Doug Wrote:

You seem to be giving the insects a very rapid reproduction rate. For most species, you wouldn’t even get a single generation in, much less enough for the new insecticide to exert its selective pressure.

I’m exaggerating, but probably not by much. Give it a few years. There are some reported cases of bacteria evolving resistance within a matter of months (I can’t remember which antibiotic it was – maybe vancomycin?) but of course they reproduce much faster and in larger numbers than insects, which are pretty good at breeding themselves.

Don’t bacteria also practice direct lateral gene transfer?

wtf? Wrote:

Before pesticides, ENTIRE COUNTRIES’ harvets were sometimes wiped out. This article makes it sound like farmers said “Hmmm, let’s spend billions of dollars for 70 years even though it actually increases loss to pests.” Ridiculous.

Tthe part you’re referring to was from Johnathan Weiner’s book, not from the article. So your beef would with Drs. May and Dobson, or perhaps with Mr. Weiner. Aside from their say-so, I don’t have any way of knowing how accurate that claim is; I would be very interested in seeing some data if you know of any. As far as the economics are concerned, pesticides certainly have a short-term benefit, but over the long-run, everything tends towards an equilibrium in which the insects get their share.

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This page contains a single entry by Steve Reuland published on October 9, 2004 10:10 AM.

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