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Diamondback moth compensatory consumption of protease inhibitor-transformed plants


  • Juliette Winterer,

    Corresponding author
    1. Department of Biology, Franklin and Marshall College, PO Box 3003, Lancaster PA 17604–3003, USA,
      Juliette Winterer. Fax: (717) 399–4548;
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  • Joy Bergelson

    1. Department of Ecology and Evolution, University of Chicago, 1101 East 57th Street, Chicago IL 60637, USA
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Juliette Winterer. Fax: (717) 399–4548;


Prior study of the effect of protease inhibitors (PIs) on diamondback moths suggests that moths are resistant to them, so PIs represent an ineffective defence against moths. However, our data suggest that diamondback moths do suffer lower growth rates when they consume plants transformed with potato protease inhibitor (PI2), but that effect is hidden by compensatory consumption. Plants, instead of gaining an advantage by lowering the insect growth rate, suffer a disadvantage as moths consume more tissue to mitigate the effect. Furthermore, PI2, when used in conjunction with another transgenic pesticidal protein, Bt (from Bacillus thuringiensis) counteracts the effectiveness of Bt at protecting plant tissue. Thus, transgenic PIs are not only less effective than previously thought in protecting Brassica plants from diamondback moths, they may actually lead to increased plant damage by the moths.

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