Modeling Evolution of &lt;I&gt;Diabrotica virgifera virgifera&lt;/I&gt; (Coleoptera: Chrysomelidae) to Transgenic Corn With Two Insecticidal Traits

Onstad, David W.; Meinke, Lance J.

doi:10.1603/ec09199

Cited by 98 publications

(112 citation statements)

References 42 publications

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“…Accordingly, in pests with low susceptibility to Cry1A and Cry2A toxins, crossresistance between Cry1A and Cry2A will generally hasten evolution of resistance. In accord with results from other simulation models (14,15,20,28), the modeling results presented here (Figs. 5 and 6) indicate that resistance to a two-toxin pyramid evolves faster when each toxin of a pyramid does not kill all individuals resistant to the other toxin, as seen with H. zea (Fig.…”

Section: Discussionsupporting

confidence: 91%

“…The deviations from ideal conditions we found with H. zea and two-toxin Bt cotton, which entail both lack of complete redundant killing and nonrecessive resistance, are likely to accelerate resistance relative to the conditions examined in previous modeling studies focusing primarily on complete or nearly complete redundant killing (RKF = 0.99-1), recessive inheritance (h p ≤ 0.05), or both (28,32,45,47,48) (see Table S3 for details).…”

Section: Discussionmentioning

confidence: 75%

“…Although most of the optimal conditions for pyramids apply to this model system, they may not apply for some other pestBt crop combinations, particularly when pests have inherently low susceptibility to one or more of the toxins in the pyramid (19,20,28,46). Here we found several deviations from optimal conditions for H. zea and Bt cotton producing Cry1Ac and Cry2Ab.…”

Section: Discussionmentioning

confidence: 76%

“…Redundant killing, which occurs when each toxin produced by a two-toxin Bt cultivar kills all insects resistant to the other toxin, is essential for optimal success of the pyramid strategy (14,15,20,28). …”

Section: Discussionmentioning

confidence: 99%

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Potential shortfall of pyramided transgenic cotton for insect resistance management

Brévault

Heuberger

Zhang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

154

222

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To delay evolution of pest resistance to transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt), the "pyramid" strategy uses plants that produce two or more toxins that kill the same pest. In the United States, this strategy has been adopted widely, with two-toxin Bt cotton replacing one-toxin Bt cotton. Although two-toxin plants are likely to be more durable than one-toxin plants, the extent of this advantage depends on several conditions. One key assumption favoring success of two-toxin plants is that they kill insects selected for resistance to one toxin, which is called "redundant killing." Here we tested this assumption for a major pest, Helicoverpa zea, on transgenic cotton producing Bt toxins Cry1Ac and Cry2Ab. Selection with Cry1Ac increased survival on two-toxin cotton, which contradicts the assumption. The concentration of Cry1Ac and Cry2Ab declined during the growing season, which would tend to exacerbate this problem. Furthermore, analysis of results from 21 selection experiments with eight species of lepidopteran pests indicates that some cross-resistance typically occurs between Cry1A and Cry2A toxins. Incorporation of empirical data into simulation models shows that the observed deviations from ideal conditions could greatly reduce the benefits of the pyramid strategy for pests like H. zea, which have inherently low susceptibility to Bt toxins and have been exposed extensively to one of the toxins in the pyramid before two-toxin plants are adopted. For such pests, the pyramid strategy could be improved by incorporating empirical data on deviations from ideal assumptions about redundant killing and cross-resistance. (Résumé d'auteur

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Potential shortfall of pyramided transgenic cotton for insect resistance management

Brévault

Heuberger

Zhang

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

154

222

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“…For the pyramided-toxin scenario, the toxin survival rate is either 1) the product of the two single toxinsurvival rates (multiplicative-toxin-survival rates), or 2) the smaller value of the two toxin-survival rates (minimum-toxin-survival rates; Onstad and Meinke 2010). Because no studies provide evidence of crossresistance to Cry1 F and Cry1Ab in O. nubilalis, we assume that cross-resistance to Cry1 F and Cry1Ab does not occur.…”

Section: Methodsmentioning

confidence: 99%

Modeling the Impact of Cross-pollination and Low Toxin Expression in Corn Kernels on Adaptation of European Corn Borer (Lepidoptera: Crambidae) to Transgenic Insecticidal Corn

et al. 2012

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We used a mathematical model with processes reflecting larval mortality resulting from feeding on crosspollinated ears or Bt ears of corn to analyze the risk of evolution of Cry-toxin resistance in Ostrinia nubilalis (Hübner). In the simulations, evolution of resistance was delayed equally well by both seed mixtures and blocks with the same proportion of refuge. Our results showed that Bt-pollen drift has little impact on the evolution of Bt resistance in O. nubilalis. However, low-toxin expression in ears of transgenic corn can reduce the durability of transgenic corn expressing single toxin, whereas durability of pyramided corn hybrids is not significantly reduced. The toxinsurvival rate of heterozygous larvae in Bt-corn ears expressing one or two proteins has more impact on evolution of Bt resistance in O. nubilalis than the parameters related to larval movement to Bt ears or the toxin-survival rate of the homozygous susceptible larvae in Bt ears. Bt resistance evolves slower when toxin mortality is distributed across the first two larval stadia than when only the first instars are susceptible to Bt toxins. We suggest that stakeholders examine toxin-survival rates for insect pests and take into account that instars may feed on different parts of Bt corn. KeywordsBt corn, resistance management, simulation Disciplines Entomology | Plant Breeding and Genetics CommentsThis article is from Environmental Entomology; 41 (2012); 200-211; doi: 10.1603/EN11133 RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. ABSTRACT We used a mathematical model with processes reßecting larval mortality resulting from feeding on cross-pollinated ears or Bt ears of corn to analyze the risk of evolution of Cry-toxin resistance in Ostrinia nubilalis (Hü bner). In the simulations, evolution of resistance was delayed equally well by both seed mixtures and blocks with the same proportion of refuge. Our results showed that Bt-pollen drift has little impact on the evolution of Bt resistance in O. nubilalis. However, low-toxin expression in ears of transgenic corn can reduce the durability of transgenic corn expressing single toxin, whereas durability of pyramided corn hybrids is not signiÞcantly reduced. The toxinsurvival rate of heterozygous larvae in Bt-corn ears expressing one or two proteins has more impact on evolution of Bt resistance in O. nubilalis than the parameters related to larval movement to Bt ears or the toxin-survival rate of the homozygous susceptible larvae in Bt ears. Bt resistance evolves slower when toxin mortality is distributed across the Þrst two larval stadia than when only the Þrst instars are susceptible to Bt toxins. We suggest that stakeholders examine toxin-survival rates for insect pests and take into account that instars may feed on different parts of Bt corn.

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Modeling a western corn rootworm,Diabrotica virgifera virgifera(Coleoptera: Chrysomelidae), maturation delay and resistance evolution inBtcorn

et al. 2013

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Modeling Evolution of <I>Diabrotica virgifera virgifera</I> (Coleoptera: Chrysomelidae) to Transgenic Corn With Two Insecticidal Traits

Cited by 98 publications

References 42 publications

Potential shortfall of pyramided transgenic cotton for insect resistance management

Potential shortfall of pyramided transgenic cotton for insect resistance management

Modeling the Impact of Cross-pollination and Low Toxin Expression in Corn Kernels on Adaptation of European Corn Borer (Lepidoptera: Crambidae) to Transgenic Insecticidal Corn

Modeling a western corn rootworm,Diabrotica virgifera virgifera(Coleoptera: Chrysomelidae), maturation delay and resistance evolution inBtcorn

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