04.10.98 20:42
US Environment Agency applies new conditions to GM Bt corn crops
This posting on genetically engineered Bt corn varieties is courtesy of the
Union of Concerned Scientists, USA (Natural Law Party Wessex)
The Gene Exchange
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A Public Voice on Biotechnology and Agriculture
EPA Requires Large Refuges
Agency moving in right direction
The Environmental Protection Agency (EPA) has, for the first time,
conditioned Bt-corn approvals on the establishment of large refuges. The
Agency's most recent approvals of Bt crops--Novartis Bt popcorn and AgrEvo's
Bt field corn--include requirements that farmers plant either 40 percent or
20-30 percent of their corn acreage in refuges of non-Bt corn, depending
upon whether or not they spray with insecticides. Earlier Agency approvals
of several Bt-corn varieties did not require refuges of specific sizes. The
refuges required for Bt cotton were only 4 percent unsprayed or 20 percent
sprayed.
The new EPA requirements are similar to recommendations in UCS's report Now
or Never: Serious New Plans to Save a Natural Pest Control.* UCS, and the
scientists who wrote the report, recommended that 50 percent of a farmer's
corn acres be planted in non-Bt-corn refuges if treated with insecticides
and 25 percent if not treated.
EPA's refuge requirements follow the recommendations developed by a group of
federal and university entomologists** working on resistance in corn
systems. Their recommendations offer two refuge options. Farmers who prefer
treating their non-Bt refuges with insecticides must establish non-Bt field
corn or popcorn on at least 40 percent of their corn acreage. Farmers who
choose not to spray are allowed to plant a smaller refuge. In either case,
non-Bt refuges must be close to the Bt crop--within 1500-2000 feet for field
corn and one-half mile for popcorn.
Non-Bt refuges are needed to delay the evolution of Bt resistance in pest
populations. The refuges are havens where Bt-susceptible insects are
expected to survive. By mating with Bt-resistant insects that develop on Bt
corn, the susceptibles help dilute the resistance trait in the insect
populations.
*To obtain Now or Never, send $14.95 plus $3 shipping/handling to UCS
Publications, Two Brattle Square, Cambridge, MA 02238-9105, or phone
617-547-5552.
**The North Central Regional Technical Committee of entomologists associated
with a USDA research project on the European corn borer and other pests.
Sources: EPA Pesticide fact sheets: 4/98--"Bacillus thuringiensis CryIA(b)
delta-endotoxin ...in corn" and 5/98--"Bacillus thuringiensis subspecies
tolworthi Cry9C protein...in corn," OPPTS, Washington, D.C.; K. Ostlie et
al., "Bt corn and European corn borer: long-term success through resistance
management," NCR Pub. 602, Univ. Minn. Ext. Ser., St. Paul, 1997.