title: Inhibition of Helicoverpa zea (Lepidoptera: Noctuidae) Growth by Transgenic Corn Expressing Bt Toxins and Development of Resistance to Cry1Ab.
abstract: Transgenic corn, Zea mays L., that expresses the Bacillus thuringiensis (Bt) toxin Cry1Ab is only moderately toxic to Helicoverpa zea (Boddie) and has been planted commercially since 1996. Growth and development of H. zea was monitored to determine potential changes in susceptibility to this toxin over time. Small plots of corn hybrids expressing Cry1F, Cry1F × Cry1Ab, Cry1Ab × Cry3Bb1, Cry1A.105 × Cry2Ab2 × Cry3Bb1, Cry1A.105 × Cry2Ab2, and Vip3Aa20 × Cry1Ab × mCry3A were planted in both 2012 and 2013 inNorth and South Carolina with paired non-Bt hybrids from the same genetic background. H. zea larvae were sampled on three time periods from ears and the following factors were measured: kernel area injured (cm(2)) by H. zea larvae, larval number per ear, larval weight, larval length, and larval head width. Pupae were sampled on a single time period and the following factors recorded: number per ear, weight, time to eclosion, and the number that eclosed. There was no reduction in larval weight, number of insect entering the pupal stadium, pupal weight, time to eclosion, and number of pupae able to successfully eclose to adulthood in the hybrid expressing Cry1Ab compared with a non-Bt paired hybrid. As Cry1Ab affected these in 1996, H. zea may be developing resistance to Cry1Ab in corn, although these results are not comprehensive, given the limited sampling period, size, and geography. We also found that the negative impacts on larval growth and development were greater in corn hybrids with pyramided traits compared with single traits.
authors: Department of Entomology, North Carolina State University, Vernon G. James Research and Extension Center, 207 Research Station Rd., Plymouth, NC 27962. ddreisig@ncsu.edu.
authors: Dominic D
authors: DD
authors: Reisig
authors: Department of Agricultural and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, 2200 Pocket Rd., Florence, SC 29506.
authors: Francis P F
authors: FP
authors: Reay-Jones
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D004731:Endotoxins / Q000494:pharmacology*; D006460:Hemolysin Proteins / Q000494:pharmacology*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology; D009036:Moths / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development; D011679:Pupa / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology; D003313:Zea mays / Q000235:genetics / Q000254:growth & development
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: eclosion; larvae; pupae