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August 23, 2000


Monarchs and Bt



This statement about 20% of monarch larvae dying came from the scientists
who conducted the experiment and was broadcast on CBS news. You can read
the full report at http://www.junkscience.com/aug00/monarch.pdf.

The CBS report is available at


Subj: RE: AGBIOVIEW: BT and Monarchs
Date: Thu, 24 Aug 2000 10:22:56 AM Eastern Daylight Time
From: Simon Barber

Just received the following from you.

"Subject: AGBIOVIEW: BT and Monarchs

AgBioView - http://www.agbioworld.org;
Archived at http://agbioview.listbot.com

'20 percent of monarch larvae eating milkweed in or
around corn fields supposedly died. But what percentage
of them would have died had chemical pesticides been
sprayed on these same corn fields?'

Write to CBS News by going to

http://cbsnews.cbs.com/feedback/frameset/0,1712,412,00.htmlm "

This statement is not attributed to anyone. Whose is it? Is this statement
factually correct - i.e. is this what the authors stated, is this what
their data supports? Or is it what was reported in the CBS media piece?
Whatever, from what little I have managed to get on this issue, it does
seem a rather irresponsible statement.

Simon Barber
Director, Plant Biotechnology Unit
6, Av. de l'ArmE9e - Legerlaan 6
1040 - Brussels
Tel: +32-2 739 11 72
Fax: +32-2 739 11 80
e-mail: s.barber@europa-bio.be

Subj: RE: AGBIOVIEW: BT and Monarchs
Date: Thu, 24 Aug 2000 10:42:44 AM Eastern Daylight Time
From: "Hector Quemada"

I'm passing on the reply of Steve Malcolm, Western Michigan University, to
James Siedow's question.


I've just read through the dialog in your message and I confess to being
dismayed at the subjectivity. James Siedow's question is perfectly valid
and it is a pity that the comments below it are so poorly informed. Our
work on monarch ecology has shown clearly that monarchs generate at least
3 generations throughout the range of Asclepias syriaca (the milkweed that
grows so abundantly in and around corn fields throughout the midwest).
Monarchs arrive in late May throughout the corn growing region and leave
in mid September. The peak breeding period for monarchs (peak larval
feeding) is throughout the whole of July and August and can extend through
September into October and starts in early June. As monarchs migrate
north from the southern USA in April and May (they leave because
temperatures become lethally hot and milkweed
senesces) the movement north generates some asynchrony and overlap of
mobile cohorts. This means that monarchs become widely distributed in
time and space throughout the entire corn growing area of the USA. Thus
the relatively low density of monarchs spread across a large geographic
area means that risk to monarchs from Bt corn pollen is as widespread as
the use of these engineered plants. There is no doubt at all that monarch
larval feeding is completely coincident with corn anthesis throughout the
entire range of corn growth in the USA. Any data that do not agree with
this prediction should be viewed with scepticism as being inadequate
because distributions of larvae are almost never uniform and are likely
to be clumped or random and require a large sampling effort to describe.
Thus casual or anecdotal observations of larval absence should not be
considered valid. I'd be happy to cite some of our publications that
provide extensive field evidence for these comments.


Date: Aug 24 2000 11:28:14 EDT
From: Daniel Charles
Subject: Re: Bt levels in pollen

"Bob MacGregor" wrote:

>It is my understanding that only one of the several Bt corn varieties
>available to farmers expresses Bt in high levels in its pollen. Further,
>I believe that this particular variety is not a major one. Can anyone
>verify this for me?

It is true that Bt levels in pollen vary quite a bit, depending on the
genetic "promoter" that's used. Event 176, which is the Bt gene in some
Novartis corn varieties, expresses Bt strongly, so pollen from those
plants is most toxic to vulnerable insects. Event 176 was the first Bt
corn on the market, but it isn't used much any more; I think only a few
percent of the corn crop these days.

The most common Bt genes, found in corn marketed by Pioneer, DeKalb, and
most small independent corn companies, still express Bt reasonably
strongly in pollen.

There is at least one gene out there (I believe from Aventis) that
doesn't express Bt in the pollen, but I don't believe it is in popular

This latest study compared mortality of larvae exposed to Event 176,
another gene called Bt11 (which is more typical of what's in the fields)
and non-Bt corn. It did note the differences between the two Bt events.


Daniel Charles
tel: 202-966-8586
fax: 603-649-0797

Subj: Re: AGBIOVIEW: Bt Corn, Shiva's CV, Research groups
Date: Thu, 24 Aug 2000 11:44:03 AM Eastern Daylight Time
From: Bruce Chassy


You are correct that the Bt176 event from Novartis contains significantly
more Bt-toxin (>10X) in the pollen than any of the other Bt-maize
varieties on the market.

Although sales vary by region and state in the US as you might expect,
Bt176 has about 2% of the overall market. So yes, even if you accept the
worst case scenarios with respect to effects on the Monarch butterfly, it
is misleading to apply the conclusions to all Bt corn.

Two good sources of information on these issues are:

Dr. Mark Sears, Professor and Chair, Department of Environmental Biology
at the Ontario Agriculture College of the University of Guelph, Guelph,
Ontario, Canada. Msears@evbhort.uoguelph.ca. (519)

Dr. Richard L. Hellmich, II, Assistant Professor of Entomology; Iowa
State University, Ames, IA; USDA research entomologist, Corn Insects
Research Unit. rlhellmi@iastate.edu. (515) 294-4509.

Both are involved in a multi-investigator collaboration on these issues.
Perhaps they will post citations to their work and offer further
information on this subject.

In Andrew Apel's 23/8/00 posting: "Irrelevance Bias", he points out the
failure of many parties in the biotech discussion to consider what he
calls the "compared to what" component. The Monarch
Butterfly issue is a perfect example of a failure to talk about a whole
ecosystem and all the factors that control population size.

Other factors that should be considered are:

* Where does the milkweed host grow?
* When do larvae hatch and does that timing overlap with maize
pollination in that region?
* Is the pollen present at toxic concentrations where the butterfly larvae
are found in the field?
* How does potential lethality to Monarch's caused by the use of
Bt-corn compare to mortality from current agricultural practices?
* What are the ancillary effects on non-target insect populations caused
by a shift to Bt corn?
* Are there ecological trade-offs that when considered as a whole, favor
or disfavor the use of Bt-corn?


>AgBioView - http://www.agbioworld.org; Archived at
>Subj: Re: CBS Monarch story
>Date: Wed, 23 Aug 2000 5:15:54 PM Eastern Daylight Time
>From: "Bob MacGregor"
>It is my understanding that only one of the several Bt corn varieties
>available to farmers expresses Bt in high levels in its pollen.
>I believe that this particular variety is not a major one. Can anyone
>verify this for me?
>Assuming this is true, then any research that lumps all Bt corn into one
>basket is inherently misleading. This further points up the importance
>of assessing products on their individual merits rather than making
>blanket statements based on prejudices about the method of developing
>these products.

Bruce M. Chassy
Assistant Dean for Biotechnology Outreach, Office of Research
College of Agricultural, Consumer and Environmental Sciences
Executive Associate Director, Biotechnology Center
University of Illinois at Urbana-Champaign

238 NSRC
1101 West Peabody Drive
Urbana, IL 61801 b-chassy@uiuc.edu