Plant Science

Resisting Resistance

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Science  22 Feb 2008:
Vol. 319, Issue 5866, pp. 1011-1013
DOI: 10.1126/science.319.5866.1011d

Bacillus thuringiensis (Bt) toxins are bacterial proteins that kill some insects and are widely used in crops for pest control. Plants expressing the Bt toxins Cry1Ac and Cry1Ab make up the majority of insect-resistant transgenic corn and cotton, respectively. A major concern has been that the pests will develop resistance; refuges, where non-transgenic plants grow next to transgenic plants, have been hypothesized to delay the evolution of resistance because resistant individuals will mate with susceptible individuals from the refuge and hence not confer resistance (if inheritance is recessive) to their offspring.

Tabashnik et al. have analyzed field studies from around the world to determine the effectiveness of the refuge strategy. They found that resistance has evolved in populations of the corn earworm at some U.S. locations, but not elsewhere nor in five other pests. Furthermore they conclude that the refuge strategy has been successful in slowing the evolution of resistance and that expressing multiple Bt toxins in single plants may further slow the appearance of resistance. — LMZ

Nat. Biotechnol. 26, 199 (2008).

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