Nature Biotechnology
18, 339 - 342 (2000)
doi:10.1038/73804
Field tests on managing resistance to Bt-engineered plantsAnthony M. Shelton1, Juliet D. Tang1, 2, Richard T. Roush3, 4, Timothy D. Metz5, 6
& Elizabeth D. Earle51
Department of Entomology, Cornell University, New York
State Agricultural Experiment Station, Geneva, NY
14456. 2
Current address: Department of Entomology and Plant
Pathology, Mississippi State University, MS 39762.
3
Department of Entomology, Cornell University,
Ithaca, NY 14853. 4
Current address: Department of Crop Protection, Waite
Institute, PMB 1, Glen Osmond, South
Australia 5064 Australia. 5
Department of Plant Breeding, Cornell University,
Ithaca, NY 14853. 6
Current address: Department of Biological Sciences,
Campbell University, Buies Creek, NC 27506
.
Correspondence should be addressed to Anthony M. Shelton ams5@cornell.edu.InsectaPlutella xylostellaBacillus thuringiensisresistancetransgenic plantsSeveral important crops have been engineered to express toxins of Bacillus
thuringiensis (Bt) for insect control. In 1999, US farmers planted
nearly 8 million hectares (nearly 20 million acres) of transgenic Bt
crops approved by the EPA. Bt-transgenic plants can greatly reduce
the use of broader spectrum insecticides, but insect resistance may hinder
this technology. Present resistance management strategies rely on a "refuge"
composed of non-Bt plants to conserve susceptible alleles. We have
used Bt-transgenic broccoli plants and the diamondback moth as a model
system to examine resistance management strategies. The higher number of larvae
on refuge plants in our field tests indicate that a "separate refuge"
will be more effective at conserving susceptible larvae than a "mixed
refuge" and would thereby reduce the number of homozygous resistant
(RR) offspring. Our field tests also examined the strategy of spraying the
refuge to prevent economic loss to the crop while maintaining susceptible
alleles in the population. Results indicate that great care must be taken
to ensure that refuges, particularly those sprayed with efficacious insecticides,
produce adequate numbers of susceptible alleles. Each insect/Bt crop
system may have unique management requirements because of the biology of the
insect, but our studies validate the need for a refuge. As we learn more about
how to refine our present resistance management strategies, it is important
to also develop the next generation of technology and implementation strategies.
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