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market-farming - Re: [Market-farming] Insects thrive on GM 'pest-killing' crops

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  • From: "Bill Shoemaker" <wshoemak AT inil.com>
  • To: "Market Farming" <market-farming AT lists.ibiblio.org>
  • Subject: Re: [Market-farming] Insects thrive on GM 'pest-killing' crops
  • Date: Mon, 31 Mar 2003 08:15:07 -0600

Jill

Interesting article. But it is only refering to resistant strains of the
pest that can actually digest the Bt safely. You only need be concerned if
you have the resistant strain of the pest (diamond back moth). While it is
possible that resistant strains are nearby, it may not mean that they
exhibit the same traits as those mentioned in the article you referenced.
The only way to know is to apply the Bt dust and watch for signs of insects
actively feeding that are unaffected by the dust.

I would also suggest that it would be premature to think this will
become a big problem. There is much that isn't understood about this
process. The work cited is only one small, laboratory study. Much more work
will need to be done to determine whether the results are consistant and why
this happens.

Lastly, I'd like to suggest that there are other means of control that
are potentially effective. We had a grad student looking at diamond back
moth on cabbage several years ago at the Research Center. He was looking at
the natural relationships of cabbage, diamond back moth and parasitoid wasps
that were native. He found that unsprayed cabbage would initially have
serious pest levels. But then parasitoid wasps would move in. They would lay
eggs in the moth larvae. The larvae would soon quit feeding. The wasp larvae
would soon form pupae and emerge as adults later, creating high populations
of the wasp. The moths had no chance at that point. This creates an
opportunity for new strategies, such as planting an early mustard crop to
serve as a host for the moth and it's larvae. The wasps then have a food
source to build populations on. as the wasp populations grow, it becomes
safer to raise the cabbage, broccoli and other high value brassicas. The
late season cabbage in his study was never sprayed but was relatively clean.
Remove a few scarred wrapper leaves and it was clean cabbage. The strategy
worked for european cabbage worm and cabbage loopers as well.

Bill Shoemaker
Sr Research Specialist, Food Crops
Univ of Illinois - St Charles Hort Research Center

>Here is an interesting news article. It raised a question for me, which
was
>not addressed in the article - if BT GMO crops help damaging larva to
>thrive, then does dusting crops with BT, as organic farmers do sometimes,
>also help them thrive? Or is it just the constant diet of BT that helps
>them thrive? - Jill, Wisconsin
>Insects thrive on GM 'pest-killing' crops
>http://news.independent.co.uk/uk/environment/story.jsp?story=392044





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