GENTECH archive





Most of the bollworms are killed, but this species  (Helicovepa
armigera) is not as sensitive as others.  Thus, although the dose
produced by the cotton is high enough to kill 100% of the insects of
some species (eg., Heliothis virescens, the major problem in the US and
Mexico) when they feed on the cotton, it is not high enough to kill all
armigera.  Some people are less sensitive to alcohol than others; some
bollworms are less sensitive to Bt than others.


<excerpt>Yes, but you don't answer the essence of my question. These
plants are genetically engineered with a toxin that is supposed to kill
bollworms when they start to eat the cotton. So why aren't some of the
bollworms killed?



<bold><fontfamily><param>Arial</param>-----Original Message-----

From: </fontfamily></bold><fontfamily><param>Arial</param>Rick Roush

<bold>To: </bold>Clive Elwell

<bold>Cc: </bold><<<<>>

<bold>Date: </bold>Friday, 4 December 1998 16:49

<bold>Subject: </bold>Re: Reply to KRRS & Monsanto, archives 448, 461,

</fontfamily>Dear Clive:

In my personal experience and from the data of many others, for the
species of bollworms that is a problem in India, the Bt cotton plants
don't kill all of the bollworms that feed on the cotton plant. In that
sense, the Bt cotton plants are only partially effective. However, even
without killing all of the bollworm larvae, the plants can yield well
and greatly reduce insecticide needs.

For some other species of bollworms (as in the US and Mexico), the Bt
cotton is very effective.



Dear Rickwhy, in your opinion, is GE Bt "only partially effective"?

Clive Elwell

<bold>-----Original Message-----

From: </bold>Rick Roush


<bold>Date: </bold>Thursday, 3 December 1998 16:09

<bold>Subject: </bold>Reply to KRRS & Monsanto, archives 448, 461, 462

With the publication of

<bold>Field trials of cotton varieties not `terminator' related

</bold>archive 462, if not on 25 Nov (see below), Prof M D
Nanjundaswamy surely knows that Bt cotton is not terminator related.

Also, it should not be expected that the Bt cotton will kill ALL
bollworms, Like many environmentally friendly approaches, it is only
partially effective.




Richard T. Roush

Associate Professor and Director Phone +61 8 8303-6591

Centre for Weed Management Systems FAX +61 8 8303-7125

Waite Institute ;-_|\

University of Adelaide / \

Glen Osmond 5064 ( )

South Australia \_;-*_/



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Cooperative Research Centre for Weed Management Systems:


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