Skip to Content.
Sympa Menu

market-farming - [Market-farming] Re: BT resistant bugs

market-farming AT lists.ibiblio.org

Subject: Market Farming

List archive

Chronological Thread  
  • From: Paul Bucciaglia <pbucciaglia AT yahoo.com>
  • To: market-farming AT lists.ibiblio.org
  • Subject: [Market-farming] Re: BT resistant bugs
  • Date: Sun, 30 Mar 2003 16:07:19 -0800 (PST)

Hi Jill,

Man, I never would have thought of the possibility that BT resistant pests would get bigger and meaner.  But it does make sense.  BT toxin is a small protein.  The most commonly used promoter , or 'gene driver', used to express proteins in plant leaves and stems  allows proteins from foreign genes to accumulate to really high levels.  So once a pest bug becomes resistant to the BT toxin, its going to get lots more nutirents  because instead of the ingested plant tissue killing the bug, its super packed with a readily metabolizable protein.

Organic farmers that spray BT cause a lot less havoc for several reasons:

-we spray only occasionally, when pest levels warrant treatment.  Contrast this with  the current BT GM technology where the protein is present at very high levels, all the time.  THis is one of the reasons why, until GM plants were widely used, there have been only a few recorded cases of BT resistance in pests.   Usually resistant bugs carry one copy of a recessive gene that mutated, conferring resistance.  If there are lots of other wild type bugs of the same species around to mate with, the resistance gene is diluted out because to carry the resistant phenotype to the next generation, the two bugs with mutant genes need to mate.  This is made more likely by BT modified plants because the kill is great the first time around, and bugs are like people, they like to have sex and will go to great lengths to find a partner, who will have also survived feeding on GM BT plants.

-BT in a spray form is very photo labile, meaning it breaks down in a day or two after spraying.  I generally spray in the evening, so when the caterpillars come out to feed they get a good dose, go back in their sheltered spots in the morning, and start feeling not so great.  The residual protein is then gone within hours or days.  Because a GM plant is constantly producing the protien, and it is sheltered and stable in the plant cell, it accumulates to much higher levels than you could ever get by spraying it.  Becasue theres not a lot of BT around when its sprayed, it seems unlikely that you could 'feed' a population of resistant bugs with BT spray unless you went out every evening and hosed your fields down.  And you are less likely to generalte bugs with resistancet to BT by spraying judiciosly in the first place, as described above. 

So thats the long answer.  The short answer to your question is no, unless you have a highly resistant population of BT bugs and you go out and spray BT for them every night, you are not going to help the pests.  You should get nice kill of your cabbage loopers, though.

One thing I wondered about in the article was this:  they said the scientists compared regular cabbage with 'treated cabbage' .  I assume that treated cabbage=BT engineeered cabbage. 

I spent about a decade genetically manipulating plants before I got disgusted with the direction of research and marketing for ag biotech products.  Thats when I went back to farming about 6 years ago.  It's a shame that the technology was used in such  simplistic manner.  In many ways the applications are just biological versions of chemical intensive agriculture, and the incredible disregard for the potential dangers by corportations (no surprise), government (owned by corporations, so no surprise) and universities (they should know better, but in many cases they are owned by corporations and government anyways) is really a shame.

Paul Bucciaglia

Fort Hill Farm, New Milford, CT

 

 

Message: 6
Date: Sun, 30 Mar 2003 07:00:51 -0600
From: "Jill Taylor Bussiere" <jdt AT itol.com>
Subject: [Market-farming] Insects thrive on GM 'pest-killing' crops
To: "Market Farming" <market-farming AT lists.ibiblio.org>
Message-ID: <009401c2f6bc$77038880$a6a63ed1@merritt>
Content-Type: text/plain; charset="iso-8859-1"

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



Do you Yahoo!?
Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop!

  • [Market-farming] Re: BT resistant bugs, Paul Bucciaglia, 03/30/2003

Archive powered by MHonArc 2.6.24.

Top of Page