Resistance management strategies for Bt rice: what have we learned so far?
1996
Cohen, M.B. | Aguda, R.M. | Romena, A.M. | Roderick, G.K. | Gould, F.L.
Rice genetically engineered with toxin genes from Bacillus thurigiensis (Bt) can provide safe and effective control of selected insect pests, but will not provide durable resistance unless Bt rice plants are carefully designed and deployed. Based on modeling and experimental studies of numerous pests systems, maintaining spatial refuges (plant parts, plants within fields, or entire fields left untreated with Bt toxins) is, in general, the most reliable approach to resistance management. Using tissue-specific gene promoters, it will likely be possible to produce rice in which toxin genes are expressed only in selected tissues. However, it is not clear what pattern of tissue-specific expression will establish a suitable refuge for stem borers. Within-field mixtures of Bt and non-Bt plants may not be an effective strategy for stem borers because larvae move from plant to plant during development. Combining Bt toxins within plants is unlikely to provide long-term suppression of resistance because some insect mutations can confer cross-resistance to multiple toxins. Combinations of Bt toxins with unrelated toxins, such as proteinase inhibitors, will probably be more durable. However, toxin combinations will be most effective if used in association with refugees
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