Sorry. I forwarded a returned item and it appears that not all the elements may
have transmitted correctly. Just in case, here is the text again. Thanks!
---------------------- Forwarded by Heather Massel/AAFRD on 08/21/2000 02:38 PM
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08/21/2000 02:12 PM
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Subject: CBS BT corn report tonight
I've learned some more information on this Bt corn segment that is to air
tonight on CBS that may be of interest.
The Internet promo runs as follows:
'In tonight's "Eye on America" report, Wyatt Andrews tells us how America's
favorite insect, the monarch butterfly,
is dying from the pollen of gene-altered corn. The results of the first field
study of genetically modified "BT corn"
are in, and, the findings have some scientists questioning the EPA's approval of
this gene-altered crop.'
I was able to get one of the people connected with the production of the story
to call me back. I am not certain
if she is more of a researcher than a producer (and with CBS they tend to do a
lot of both) but she's apparently
been heavily involved in this issue for more than a year.
I asked her to tell me on which study this report was based, and she told me it
had just been published on the Oecologia
site. Here is the abstract of the study to which she refers:
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© Springer-Verlag 2000
Field deposition of Bt transgenic corn pollen: lethal effects on the monarch
Laura C. Hansen Jesse (1) and John J. Obrycki (1),
Department of Entomology, Iowa State University, Ames, IA 50011, USA
We present the first evidence that transgenic Bacillus thuringiensis (Bt) corn
pollen naturally deposited on Asclepias syriaca; common milkweed, in a corn
causes significant mortality of Danaus plexippus L. (Lepidoptera: Danaidae)
Larvae feeding for 48 h on A. syriaca plants naturally dusted with pollen from
plants suffered significantly higher rates of mortality at 48 h (20±3%) compared
larvae feeding on leaves with no pollen (3±3%), or feeding on leaves with non-Bt
(0%). Mortality at 120 h of D. plexippus larvae exposed to 135 pollen grains/cm2
transgenic pollen for 48 h ranged from 37 to 70%. We found no sub-lethal effects
plexippus adults reared from larvae that survived a 48-h exposure to three
concentrations of Bt pollen. Based on our quantification of the wind dispersal
pollen beyond the edges of agricultural fields, we predict that the effects of
pollen on D. plexippus may be observed at least 10 m from transgenic field
However, the highest larval mortality will likely occur on A. syriaca plants in
or within 3 m of the edge of a transgenic corn field. We conclude that the
effects of transgenic insecticidal crops need to be evaluated more fully before
planted over extensive areas.
Key words. Danaus plexippus - Bacillus thuringiensis - Bt corn - Transgenic
- Risk assessment
Here is the link to the Oecologia website for both the abstract and the study:
I wish I had a LINK ID but don't (apparently they mail these things and it could
take 2+ weeks) so I can't view
I would be interested to know if anyone else on this listserve has access to
this study and their reaction to it.
As someone who has absolutely no scientific background beyond all the
information I read every day, I am
curious: would a refuge belt address the pollen drift issue?
I also asked the CBS person whether they had interviewed some of the Canadian
scientists who have done
work in this area (especially Dr. Mark Sears from the University of Guelph.)
I was told they had spoken with him and others but had only used American
information in the story (which stands
to reason, given the name of the segment.)
Tried to find out more but couldn't -- we just have to "tune in to see it!"
Thanks to Andrew Apel for giving us the heads-up on this.
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