Bt - more

[Chip Taylor]

Cherubini
It would be very helpful if you or your colleagues would provide
listmembers and the public with a scenario or model in which this
"potential" to reduce monarch numbers could be realized. Tell us the
assumptions that would have to be made. That way listmembers and the
public could understand the scientific basis for your deep concern.

Taylor
>Date: Fri, 21 May 1999 17:57:50 -0500
>To: dplex-l at raven.cc.ukans.edu
>From: Monarch Watch <monarch at ukans.edu>
>Subject:  Bt corn - potential impact
>Cc:
>Bcc:
>X-Attachments:
>
>Actually, it is quite easy to outline a variety of scenarios for the
>impact of Bt corn pollen on monarchs from near zero to the loss of perhaps
>100 million monarchs from the fall population. I could outline all the
>assumptions for these scenarios but this would lead to an endless and
>unproductive debate about these assumptions and conditions. Impact cannot
>be assessed through debate. It takes research and the research requires
>trained personnel, time and MONEY. At this time, there is no money for
>this research. If we want the question answered, someone has to work hard
>to get the money and commit themselves to the project.
>
>Research on the potential impact of Bt corn should start with a list of
>observations followed by a list of questions concerning what we need to
>know. Some of the questions should give rise to testable hypotheses. Many
>of the questions that need to be answered have been mentioned in the
>various news articles in newspapers and websites. John Losey mentioned
>several such lines of investigation in his discussion on NPR this
>afternoon.
>
>For those of you who are directing students, why not challenge them to
>work out the protocols for assessing Bt impact on monarch populations?
>It's not hard to work out what needs to be done. What do we need to know
>about the Bt corn hybrids (there are many and they don't all have the same
>toxicity)? What are the LD50's of different Bt's in pollen and how do
>these vary with concentration? What do we need to know about the temporal
>and spatial distribution of corn pollen? What do we need to know about the
>half life of the Bt toxicity? What do we have to know about the
>distribution and abundance of milkweeds and monarchs within and adjacent
>to Bt corn fields? What is the relationship of corn  pollen shedding with
>latitude and season and how does this intersect with the different monarch
>generations? If most of the migratory population is derived from eggs laid
>between 25 July and 5 August, will the size of the migratory population be
>more greatly impacted if larvae are exposed to Bt pollen before 25 July or
>after this date? There is more of course. However, if we had answers to
>many of these questions, we would be able to assess the impact of 20+
>million acres of Bt corn on monarch populations.


Monarch Watch
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Snail:  c/o O.R. Taylor, Dept. of Entomology, Univ. of KS, Lawrence KS 66045