title: Effects of refuges on the evolution of resistance to transgenic corn by the western corn rootworm, Diabrotica virgifera virgifera LeConte.
abstract: BACKGROUND
  Diabrotica virgifera virgifera LeConte is a major pest of corn and causes over a billion dollars of economic loss annually through yield reductions and management costs. Corn producing toxins derived from Bacillus thuringiensis (Bt) has been developed to help manage D. v. virgifera. However, previous studies have demonstrated the ability of this species to evolve resistance to Bt toxins in both laboratory and field settings.
  
  
  RESULTS
  We used an experimental evolution approach to test the refuge strategies for delaying resistance of D. v. virgifera to corn producing Bt toxin Cry34/35Ab1. In the absence of refuges, D. v. virgifera developed resistance to Bt corn after three generations of selection. In some cases, non-Bt refuges reduced the level of resistance compared with the strain selected in the absence of refuges, but refuge strains did show reduced susceptibility to Bt corn compared with the unselected strain.
  
  
  CONCLUSIONS
  In this study, non-Bt refuges delayed resistance to Bt corn by D. v. virgifera in some cases but not others. Combining the refuge strategy with pyramids of multiple Bt toxins and applying other pest management strategies will likely be necessary to delay resistance of D. v. virgifera to Bt corn.
authors: Department of Entomology, Iowa State University, Ames, IA, USA.|Department of Biological Sciences, Lock Haven University, Lock Haven, PA, USA.
authors: Jennifer
authors: J
authors: Deitloff
authors: Department of Entomology, Iowa State University, Ames, IA, USA.
authors: Mike W
authors: MW
authors: Dunbar
authors: Department of Entomology, Iowa State University, Ames, IA, USA.
authors: David A
authors: DA
authors: Ingber
authors: USDA-ARS, University of Missouri, Columbia, MO, USA.
authors: Bruce E
authors: BE
authors: Hibbard
authors: Department of Entomology, Iowa State University, Ames, IA, USA.
authors: Aaron J
authors: AJ
authors: Gassmann
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000494:pharmacology; D005075:Biological Evolution; D001517:Coleoptera / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D004731:Endotoxins / Q000235:genetics / Q000494:pharmacology; D006460:Hemolysin Proteins / Q000235:genetics / Q000494:pharmacology; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics; D003313:Zea mays / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides
keywords: agriculture; insect resistance management; refuge strategy; transgenic crops