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TITLE:
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RESISTANCE TO BACILLUS THURINGIENSIS INSECTICIDAL PROTEINS
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BRIEF:
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Heliothis virescens, the tobacco budworm, is a major pest of cotton that is effectively controlled by plants expressing Bacillus thuringiensis (Bt) Cry1Ac protein. While the current generation of Bt cotton controls H. virescens, it is less effective in controlling Helicoverpa zea and does not control Spodoptera species. To offset limits in insect control, second generation Bt cotton targets additional lepidopteran species by expressing combinations of Cry1Ac with Cry2Ab or Cry1Fa. Although Bt cotton is extremely successful, its continued success depends on methods to detect and delay insect resistance to the Cry proteins. Knowledge of Cry toxin receptors and resistance mechanisms evolved by this pest are vital to maintain the utility of Bt plant technology. The overall goal of UGA entomologists is to provide a scientific basis for selecting Bt proteins for use in plants. They select Bt proteins that have useful insecticidal properties, and then conduct molecular analyses to predict how insects might evolve resistance to those proteins. A second approach uses insects selected in the laboratory for Bt resistance. They analyze those insects for changes that led to Bt resistance. Overall, these comparative studies of Bt susceptible and resistant H. virescens strains have yielded new insights into Bt toxin mode of action and resistance mechanisms. These data indicate that insects adapt to Bt toxin via complex physiological adaptations, and scientists' understanding of these adaptations can lead to more effective control strategies for resistant pest populations.
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SOURCE(S):
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Michael J. Adang (Professor), 706-542-2436, adang@uga.edu
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COLLABORATOR(S):
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BASED UPON:
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Discovering mechanisms in insects that confer resistance to Bacillus thuringiensis insecticidal proteins
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