Proceedings 2008 |
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CD-AY-332 |
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Traits for Insect Control with Transgenic Bt Corn: What, Why, and How . . . Now and in the Future The impact of transgenic Bt corn hybrids on insect populations and their control has been dramatic, transforming the way we think about and implement insect management strategies. Some of the first Bt corn hybrids, commercialized in the mid-1990s, were extremely effective against corn borers (both European and southwestern), giving corn growers a glimpse of the future potential for transgenic technology in agriculture. However, the commercialization of Bt corn hybrids also introduced the somewhat complex concept of insect resistance management (IRM) with non-Bt corn refuges, placing further emphasis on management in contrast to in-the-moment decision making. Early in this decade, the commercialization of transgenic Bt corn hybrids for control of corn rootworms generated even more interest and excitement among corn growers who enthusiastically adopted the technology to control the most important insect pests of corn in North America. In due course, transgenic traits for control of both corn borers and corn rootworms were “stacked” in elite corn hybrids with traits for herbicide tolerance, resulting in double-, triple-, and quad-stacked hybrids. Concurrently, “new and improved” versions of transgenic Bt corn hybrids were introduced. And on the near horizon are the anticipated products Optimum® AcreMaxTM 1 Insect Protection (so-called “refuge in a bag” from Pioneer) and SmartStaxTM (cross-licensed by Monsanto and Dow AgroSciences), an 8-gene stacked combination in corn that will express more than one protein for control of the same target insect, as well as provide herbicide tolerance. All of these past and proposed future transgenic corn developments promise a dizzying array of choices for corn growers. It is likely that the IRM guidelines and requirements will change, too, creating even more uncertainty about implementation and compliance. The thrust of the discussion will be a review of the currently available and projected traits and their combinations for insect management in corn hybrids and how integrated pest management (IPM) and IRM will be influenced by their widespread use. Results from applied research efforts will supplement the discussion. Where appropriate, case studies will be included to help elucidate some of the complexities and potential drawbacks of using transgenic technology for insect management. Kevin SteffeyProfessor of Agricultural Entomology |