When and where a seed mix refuge makes sense for managing insect resistance to Bt plants

Carroll, Matthew; Head, Graham P.; Caprio, Michael A.

doi:10.1016/j.cropro.2012.02.015

Cited by 64 publications

(44 citation statements)

References 15 publications

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“…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: 94%

Potential shortfall of pyramided transgenic cotton for insect resistance management

Brévault

Heuberger

Zhang

et al. 2013

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

149

218

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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: Discussionmentioning

confidence: 94%

Potential shortfall of pyramided transgenic cotton for insect resistance management

Brévault

Heuberger

Zhang

et al. 2013

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

149

218

View full text Add to dashboard Cite

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“…In the Brazilian crop production system, there is a low adoption of refuge areas. An alternative to the structured refuge strategy would be the use of seed mixes that contain non-Bt seeds ("refuge-in-a-bag"), thus transferring the responsibility of refuge implementation to the company providing the technology (Carroll et al, 2012). This ensures that a refuge will be present within every Bt crop field .…”

Section: Introductionmentioning

confidence: 98%

“…The seed mix strategy assumes a recessive inheritance of resistance and that larval mobility of target insects is negligible (Mallet and Porter, 1992;Tabashnik, 1994;Carroll et al, 2012;Carri ere et al, 2016). For the Vip3Aa20 protein, recessive inheritance was reported for a laboratory-selected strain of FAW .…”

Section: Introductionmentioning

confidence: 99%

Functional dominance of different aged larvae of Bt-resistant Spodoptera frugiperda (Lepidoptera: Noctuidae) on transgenic maize expressing Vip3Aa20 protein

et al. 2016

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“…We found the same effect when density-independent rainfall kills pest eggs and neonates. Other kinds of density-independent and genotype-independent mortality can play a signiÞcant role in evolution of resistance (Carroll et al 2012). Heimpel et al (2005) concluded that for genotype-independent mortality to inßuence evolution in a landscape consisting of refuge and toxic habitats, it must be followed by density-dependent mortality in a later life stage.…”

Section: Discussionmentioning

confidence: 99%

Modeling the Integration of Parasitoid, Insecticide, and Transgenic Insecticidal Crop for the Long-Term Control of an Insect Pest

et al. 2013

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The tools of insect pest management include host plant resistance, biological control, and insecticides and how they are integrated will inßuence the durability of each. We created a detailed model of the population dynamics and population genetics of the diamondback moth, Plutella xylostella L., and its parasitoid, Diadegma insulare (Cresson), to study long-term pest management in broccoli Brassica oleracea L. Given this pestÕs history of evolving resistance to various toxins, we also evaluated the evolution of resistance to transgenic insecticidal Bt broccoli (expressing Cry1Ac) and two types of insecticides. Simulations demonstrated that parasitism provided the most reliable, long-term control of P. xylostella populations. Use of Bt broccoli with a 10% insecticide-free refuge did not reduce the long-term contribution of parasitism to pest control. Small refuges within Bt broccoli Þelds can delay evolution of resistance Ͼ30 generations if resistance alleles are rare in the pest population. However, the effectiveness of these refuges can be compromised by insecticide use. Rainfall mortality during the pestÕs egg and neonate stages signiÞcantly inßuences pest control but especially resistance management. Our model results support the idea that Bt crops and biological control can be integrated in integrated pest management and actually synergistically support each other. However, the planting and maintenance of toxin-free refuges are critical to this integration.

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When and where a seed mix refuge makes sense for managing insect resistance to Bt plants

Cited by 64 publications

References 15 publications

Potential shortfall of pyramided transgenic cotton for insect resistance management

Potential shortfall of pyramided transgenic cotton for insect resistance management

Functional dominance of different aged larvae of Bt-resistant Spodoptera frugiperda (Lepidoptera: Noctuidae) on transgenic maize expressing Vip3Aa20 protein

Modeling the Integration of Parasitoid, Insecticide, and Transgenic Insecticidal Crop for the Long-Term Control of an Insect Pest

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