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[SANET-MG] environmental impact of gm sugar beet
February 14, 2005
Prof. Joe Cummins
“Environmental Impacts of Genetically Modified Sugar Beet”
Genetically modified (GM) sugar beet has been commercially produced in
the United States since 1998 and later by Canada, Japan and Australia.
American releases included a strain resistant to the herbicide
glyphosate and another resistant to the herbicide glufosinate. The
United State’s releases were all accompanied by environmental
assessment by the United States department of Agriculture (USDA) Animal
and Plant Health Inspection Service (APHIS). The USDA/APHIS
environmental assessments consisted on the impact of the herbicide
resistant sugar beet on a few representative non-target animals and the
chance of pollen and seed pollution of weeds related to sugar beet and
unmodified sugar beets (1,2,3) These reviews determined that there was
“no significant impact” from the GM sugar beets but the studies were
very limited and mainly based on laboratory studies . In 2003 Britain
released the results of extensive studies on GM sugar and fodder
beets, spring oilseed rape and forage maize. The studies showed that
herbivores, detritivores and many of the predators and parasites are
sensitive to the changes in weed communities that result from the
introduction of the herbicide regime (4,5,6,7).
The weed management plans that resulted in detrimental impact on
biodiversity resulted from weed control that was more extensive than
that achieved using conventional herbicides , which have a relatively
poor spectrum of activity and margin of selectivity.. The impact on weed
seed production resulted in a lack of bird food. Lack of bird food is
deemed to be one of the major problems of modern agricultural
production in Britain. A method was explored to increase available bird
food in GM sugar beet crops. A rather complicated protocol was devised
involving spraying a twenty centimeter band of herbicide down crop
rows 55 centimeters apart. Benefit was achieved by timing the spray
application early spray application allowed weed seed yields without
impacting production(8). The rather complex protocol for glyphosate
spray application was designed to provide adequate bird food without
sacrificing sugar beet yield.
The band spay application technique may, indeed , allow farmers to
produce GM sugar beets without sacrificing bird biodiversity provided
they can be educated to follow the complex regime. The band spray
strategy seems like a superior way to produce herbicide tolerant
weeds. As the concentrated herbicide diffuses laterally from the band a
concentration gradient of herbicide will be produced. The gradient will
allow selection of herbicide tolerant variants of the various weed
species. Glyphosate tolerance is a growing problem in North America
where glyphosate is used extensively. The concentrated band application
of glyphosate would be analogous to the traditional method for selecting
resistant microbial mutants on a Petri dish which has been used for
over fifty years. It is equally clear that a gradient of herbicide
concentration will likely effectively select resistant weeds.
Interestingly, the GM sugar beet strain used in the studies of
reference 8 and in the Farm Scale Evaluations was Monsanto event
number 77 (4,5) as was an event 77 used in USDA/APHIS environment
assessment (1). The authors of the Farm Scale Evaluation believed that
the GM sugar beet used in their studies contained both the gene for
glyphosate insensitivety (EPSPS) and a gene active in destroying the
glyphosate, glyphosate oxyreductase, taken into resistant cell.
However, USDA/APHIS reports acknowledged that the glyphosate
oxyreductase gene was present in envent 77 but defective and unable to
destroy the glyphosate taken into the GM sugar beet., reference 9
provides references and discussion including the approval of event 77
sugar beet. The failure of event 77 to destroy glyphosate taken into the
resistant beets results in elevated glyphosate in the crop. The Farm
Scale Evaluation seems ot have neglected the impact of elevated level
of herbicide in the GM crops on the various ecological parameters that
they studied.
In the final analysis it is most important that the deployment of GM
sugar beet should not eliminate the wild birds of Great Britain. The
most reasonable approach to maintaining biological diversity is to
solely deploy organic sugar beets and to forget about GM sugar beet. It
seems unlikely that any degree of tinkering with glyphosate application
will be employed realistically and even if tried may succumb to
vicissitudes in weather . Even though the news media may succumb to
seductive schemes it is unlikely that farmers will take them seriously.
References
1.USDA/APHIS Novartis Seeds and Monsanto Company Petition 98-173-01p
for determination of non-regulated status for transgenic glyohosate
tolerant sugar beet line GTSB77 Environment Assessment and finding of no
significant impact 1998 http://www.aphis.usda.gov/brs/not_reg.html
2.USDA/APHIS AgEvro USA company petition 97-336-01p for determination
of non-regulated status for transgenic glufosinate tolerant sugar beet
transformation event T120-7 Finding of no significant impact 1998
http://www.aphis.usda.gov/brs/not_reg.html
3. USDA/APHIS Monsanto Company and KWS SAAT AG petition 03-323-01p for
determination of non-regulated status for roundup ready sugar beet event
H7-1 Environment Assessment 2004 http://www.aphis.usda.gov/brs/not_reg.html
4. Firbank, L. Introduction 2003 Phil.Trans.R.Soc. Lond. B 358,1777-8
5.
Champion,G,May,M,Bennett,S,Brooks,D,Clark,S,Daniels,R,Firbank,L,Haughton,A,Hawes,C,
Heard,M,Perry,J,Randle,Z,Rossall,M,Rothery,P,Skellern,M,Scott,R,Squire,G.
and Thomas. M. Crop management and agronomic context of the Farm Scale
Evaluations of genetically modified herbicide-tolerant crops 2003 Phil.
Trans. R. Soc. Lond. B 358, 1801–18
6.
Hawes,C,Haughton,A,Osborne,J,Roy,D,Clark,S,Perry,J,Rothery,P,Bohan,D,Brooks,D,
Champion,G,Dewar,A,Heard,M,Woiwod,I,Daniels,R,Young,M,Parish,A,Scott,R,Firbank,L.
and Squire,S. Responses of plants and invertebrate trophic groups to
contrasting herbicide regimes in the Farm Scale Evaluations of
genetically modified herbicide-tolerant crops 2003 Phil. Trans. R. Soc.
Lond. B 358, 1899–1913
7.
Squire,G,Brooks,D,Bohan,D,Champion,G,Daniels,R,Haughton,A,Hawes,C,Heard,M,Hill,M,
May,M,Osborne,J,Perry,J,Roy,D,Woiwod,I. and Firbank,L. On the rationale
and interpretation of the Farm Scale Evaluations of genetically modified
herbicide-tolerant crops 2003 Phil. Trans. R. Soc. Lond. B 358, 1779–99
8. May,M,Champion,G,Dewar,A, Qi,A. and Pidgeon,J. Management of
genetically modified herbicidetolerant sugar beet for spring and autumn
environmental benefit 2005 Proc. R. Soc. B 272, 111–9
9.Cummins,J. GM sugar beet gone sour 2004 http://www.i-sis.org.uk/
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