Bt corn flap

[Mike Griggs]

In article <954339250snz at nwjones.demon.co.uk>, Neil at nwjones.demon.co.uk 
wrote:

> This could easily
>occur once the majority of the population of a species carries a gene
>that that works against one strain. Natural selection works just
>like this.
>The consequences are that we actually decrease the ability of Natural
>predators to control pests. That is not a smart thing to do.

---Lots snipped-- check original posting for complete post

The cry3 gene incorporated in the Bt corn does have a very specific site 
of activity.  A followup product to resistance in comercial Bt products 
will be to find another effective gene (cry4,5,7,?) that would target 
another site not yet expressing resistance.

Induction of resistance to a specific Bt strain does not necessarily 
imply resistance to other strains.  Site specificity of the cry3 Bt 
toxin will not necessarily induce other Bt strains to gain resistance.   
The broad spectrum of organisms worldwide that are grouped into "Bt"  is 
just being defined and catagorized.  These strains  have as yet an 
undefined mode of action and may not affect sites within the  the target 
organism for which genes for resistance are incorporated.  Thus the holy 
grail of pest management!

Problems arrise from the intense selection placed on an ecosytem by 
repeated application of such selective management tools.   Bt as we know 
it today took 50 years to develop and may have ten years of use as an 
insect control agent.   


Mike