Strong oviposition preference for Bt over non-Bt maize in Spodoptera frugiperda and its implications for the evolution of resistance.

Authors:
Ben Raymond
Ben Raymond
School of Biological Sciences
Kansas City | United States
Denis J Wright
Denis J Wright
Imperial College London
United Kingdom
Dr. Camilo Ayra-Pardo, PhD
Dr. Camilo Ayra-Pardo, PhD
Henan Provincial Engineering Laboratory of Insect Bio-reactor / Nanyang Normal University
Associate Professor
Plant Biotechnology
Nanyang, Henan | China

BMC Biol 2014 Jun 16;12:48. Epub 2014 Jun 16.

Centre for Genetic Engineering and Biotechnology (CIGB), Havana 10600, Cuba.

Background: Transgenic crops expressing Bt toxins have substantial benefits for growers in terms of reduced synthetic insecticide inputs, area-wide pest management and yield. This valuable technology depends upon delaying the evolution of resistance. The 'high dose/refuge strategy', in which a refuge of non-Bt plants is planted in close proximity to the Bt crop, is the foundation of most existing resistance management. Most theoretical analyses of the high dose/refuge strategy assume random oviposition across refugia and Bt crops.

Results: In this study we examined oviposition and survival of Spodoptera frugiperda across conventional and Bt maize and explored the impact of oviposition behavior on the evolution of resistance in simulation models. Over six growing seasons oviposition rates per plant were higher in Bt crops than in refugia. The Cry1F Bt maize variety retained largely undamaged leaves, and oviposition preference was correlated with the level of feeding damage in the refuge. In simulation models, damage-avoiding oviposition accelerated the evolution of resistance and either led to requirements for larger refugia or undermined resistance management altogether. Since larval densities affected oviposition preferences, pest population dynamics affected resistance evolution: larger refugia were weakly beneficial for resistance management if they increased pest population sizes and the concomitant degree of leaf damage.

Conclusions: Damaged host plants have reduced attractiveness to many insect pests, and crops expressing Bt toxins are generally less damaged than conventional counterparts. Resistance management strategies should take account of this behavior, as it has the potential to undermine the effectiveness of existing practice, especially in the tropics where many pests are polyvoltinous. Efforts to bring down total pest population sizes and/or increase the attractiveness of damaged conventional plants will have substantial benefits for slowing the evolution of resistance.

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Source
http://dx.doi.org/10.1186/1741-7007-12-48DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4094916PMC

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June 2014
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