title: Impact of the Bt Corn Proteins Cry34/35Ab1 and Cry3Bb1, Alone or Pyramided, on Western Corn Rootworm (Coleoptera: Chrysomelidae) Beetle Emergence in the Field.
abstract: Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a major pest of corn, Zea mays L. The effect of the Bt proteins Cry34/35Ab1 and Cry3Bb1, alone or pyramided in corn hybrids on D. v. virgifera adult emergence was evaluated in field experiments for 3 yr. Experiments were infested artificially with 2,500 viable D. v. virgifera eggs per row meter of corn. The reduction in beetle emergence compared with non-Bt controls, from Cry34/35Ab1, Cry3Bb1, and the pyramided hybrids ranged from 64.3 to 97.4%, 91.1 to 95.2%, and 98.1 to 99.6%, respectively. The sex ratio of emerged beetles was usually female-biased from the Cry3Bb1 and pyramided treatments, but not from Cry34/35Ab1 treatment alone. Emergence from all Bt hybrids was delayed compared with the control, with the delay longest from the pyramided hybrid. In 2013, three egg infestation levels were tested, with density-dependent mortality observed at 1,250 viable eggs per row meter. The effect of Bt proteins on the emergence timing and sex ratio of D. v. virgifera may impact the suitability of resistance management plans, specifically the effectiveness of the refuge strategy. Susceptible males emerging from refuge might not be synchronized to mate with potentially resistant females emerging later from Bt corn hybrids.
authors.affiliation: Department of Plant Agriculture, Ridgetown Campus, University of Guelph, 120 Main St. E., Ridgetown, ON N0P 2C0, Canada.
authors.forename: A J
authors.initials: AJ
authors.lastname: Hitchon
authors.affiliation: Department of Plant Agriculture, Ridgetown Campus, University of Guelph, 120 Main St. E., Ridgetown, ON N0P 2C0, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Smith
authors.affiliation: North Central Agricultural Research Laboratory, 2923 Medary Ave., Brookings, SD, 57006.
authors.forename: B W
authors.initials: BW
authors.lastname: French
authors.affiliation: Department of Plant Agriculture, Ridgetown Campus, University of Guelph, 120 Main St. E., Ridgetown, ON N0P 2C0, Canada. aschaafs@uoguelph.ca.
authors.forename: A W
authors.initials: AW
authors.lastname: Schaafsma
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry* / Q000235:genetics; D001517:Coleoptera / Q000382:microbiology* / Q000502:physiology; D004731:Endotoxins / Q000235:genetics / Q000494:pharmacology*; D005260:Female; D008297:Male; D009864:Ontario; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development; D012744:Sex Ratio; D003313:Zea mays / Q000235:genetics / Q000254:growth & development*
chemical_list: C507666:Cry3Bbl endotoxin, Bacillus thuringiensis; D004731:Endotoxins
keywords: Diabrotica; maize; mating; refuge; resistance management