BT Pollen not so Dangerous to Monarchs

[Susan Courson]

I've read that report. It's what got everyone alerted to the issue.
I've been searching for any recent research efforts.  Thanks anyway.

Robin Baker wrote:

> Also check out Science News Online at:
>
> http://www.sciencenews.org/sn_arc99/5_22_99/fob1.htm
>
>
> Susan Courson wrote:
>
>> Thank you for this post.  I have been searching for information on
>> this issue.  We
>> are writing a series of lessons to be used in a biotechnology
>> workshop this summer
>> for secondary science teachers.
>>
>> Rcjohnsen wrote:
>>
>> > QUICK LINKS
>> > Click on the banner above to visit one of our advertisers.
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>> > NEXT >Source:           University Of Guelph
>> (http://www.uofguelph.ca)
>> > Contact:                Margaret Boyd , Research Communications
>> Officer
>> > Phone: 519-824-4120, Ext. 2776; Email:
>> margaret at research.uoguelph.ca
>> > Date:           Posted 2/9/2000
>> >
>> > New Research Suggests Bt-Corn Not Harmful To Monarch Butterfly
>> >
>> >    The Monarch butterfly is alive and well, despite exaggerated
>> and misleading
>> > reports that biotechnology is threatening it, says a University of
>> Guelph
>> > researcher.
>> > Field research conducted by Prof. Mark Sears, chair of the
>> University of
>> > Guelph's Department of Environmental Biology and chair of the
>> Canadian Corn
>> > Pest Coalition, shows pollen from Bt corn -- Bacillus
>> thuringiensis, a
>> > naturally-occurring soil-borne bacterium which selectively targets
>> specific
>> > groups of insects -- is not found in high enough doses on most
>> milkweed plants
>> > (the food plant of the caterpillars) to hurt Monarch butterfly
>> larvae.
>> >    Although Bt is harmless to humans and other animals, a U.S.
>> study claimed
>> > pollen from Bt-corn damaged Monarch butterfly larvae. The study
>> sparked a media
>> > frenzy and public concern about genetically modified foods.
>> > Sears says the U.S. study didn't demonstrate to what extent its
>> preliminary
>> > findings applied to field situations. The study was completed in a
>> lab, and the
>> > dosage of pollen used wasn't reported.
>> >    "The actual threat to the Monarch butterfly can only be
>> determined by
>> > assessing the dosage that affects the larvae and their degree of
>> exposure to
>> > Bt-corn pollen in the field," says Sears.
>> >    Sears is leading a two-year project to determine the ecological
>> impacts of
>> > Bt-corn pollen on selected non-target butterfly species, including
>> the Monarch.
>> > So far, studies indicate that Bt- corn is not as big a threat as
>> > environmentalists and the news media had anticipated.
>> >    "Outside of corn fields, you probably wouldn't find
>> concentrated dosages of
>> > pollen because wind and rain removes it from the surface of the
>> milkweed
>> > leaves," says Sears. Sears's study focused on Bt pollen and how
>> far it travels.
>> > He examined milkweed stands in corn fields, at their edges, then
>> at distances
>> > of five, 10 , 25, 50 and 100 metres away. He found that within the
>> fields,
>> > approximately 150 pollen grains/cm2 were found on milkweed leaves.
>> At the field
>> > edges, 80 to 100 grains/cm2 were found, and at five metres, only
>> one grain/cm2
>> > was found. He then compared these findings to values obtained from
>> a
>> > "dose-response assay" — from which data of increasing doses are
>> plotted against
>> > increased mortality rates — to determine dosages with negative
>> effects on
>> > Monarch butterfly larvae.
>> > Results show that 135 grains/cm2 — the lowest dosage he has tested
>> on milkweed
>> > leaves so far and similar to that found on milkweed leaves in the
>> field — had
>> > no greater effect on Monarch larvae than when they were fed non-Bt
>> pollen.
>> >    "Our findings are consistent with other studies across North
>> America," says
>> > Sears. "Bt- corn has always shown to be harmless to both humans
>> and animals,
>> > and we now know it isn't a major threat to the Monarch butterfly."
>>
>> >    Sears is being assisted by research associate Diane
>> Stanley-Horn and
>> > research technician Heather Mattila from the University of Guelph,
>> along with
>> > seed industry representatives and corn growers. His research is
>> sponsored by
>> > the Canadian Food Inspection Agency and Environment Canada.
>> >
>> >
>> ------------------------------------------------------------------------
>>
>> > Note: This story has been adapted from a news release issued by
>> University Of
>> > Guelph for journalists and other members of the public. If you
>> wish to quote
>> > from any part of this story, please credit University Of Guelph as
>> the original
>> > source. You may also wish to include the following link in any
>> citation:
>> >
>> > http://www.sciencedaily.com/releases/2000/02/000208094017.htm
>> >
>> >
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> --
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>
> Robert A. Baker
> Oregon City, OR, USA
>