title: Western corn rootworm (Coleoptera: Chrysomelidae) dispersal and adaptation to single-toxin transgenic corn deployed with block or blended refuge.
abstract: A simulation model of the temporal and spatial dynamics and population genetics of western corn rootworm, Diabrotica virgifera virgifera LeConte, was created to evaluate the use of block refuges and seed blends in the management of resistance to transgenic insecticidal corn (Zea mays  L.). This Bt corn expresses one transgenic corn event, DAS-59122-7, that produces a binary insecticidal protein toxin (Cry34Ab1/Cry35Ab1) and provides host-plant resistance. The model incorporates the latest information about larval and adult behavior. Results of this modeling effort  indicate that the seed-blend scenarios in many cases produced equal or greater durability than block refuges that were relocated each year. Resistance evolved in the most likely scenarios in 10-16 yr. Our standard analysis presumed complete adoption of 59122 corn by all farmers in our  hypothetical region, no crop rotation, and 100% compliance with Insect Resistant Management (IRM) regulations. As compliance levels declined, resistance evolved faster when block refuges were deployed. Seed treatments that killed the pest when applied to all seeds in a seed blend or just to  seeds in Bt corn blocks delayed evolution of resistance. Greater control of the pest population by the seed treatment facilitated longer durability of the transgenic trait. Therefore, data support the concept that pyramiding a transgenic insecticidal trait with a highly efficacious insecticidal  seed treatment can delay evolution of resistance.
authors.affiliation: Pioneer Hi-Bred International, Inc., Wilmington, DE 19880, USA.
authors.forename: Zaiqi
authors.initials: Z
authors.lastname: Pan
authors.forename: David W
authors.initials: DW
authors.lastname: Onstad
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Nowatzki
authors.forename: Bruce H
authors.initials: BH
authors.lastname: Stanley
authors.forename: Lance J
authors.initials: LJ
authors.lastname: Meinke
authors.forename: J Lindsey
authors.initials: JL
authors.lastname: Flexner
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001522:Behavior, Animal; D001517:Coleoptera / Q000235:genetics*; D003198:Computer Simulation; D004731:Endotoxins; D005260:Female; D006460:Hemolysin Proteins; D054884:Host-Pathogen Interactions; D007305:Insecticide Resistance; D007306:Insecticides; D007814:Larva / Q000502:physiology; D008124:Locomotion; D008297:Male; D008957:Models, Genetic; D030821:Plants, Genetically Modified / Q000469:parasitology; D011157:Population Dynamics; D012726:Sexual Behavior, Animal; D003313:Zea mays / Q000469:parasitology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis