title: Resistance of Trichoplusia ni populations selected by Bacillus thuringiensis sprays to cotton plants expressing pyramided Bacillus thuringiensis toxins Cry1Ac and Cry2Ab.
abstract: Two populations of Trichoplusia ni that had developed resistance to Bacillus thuringiensis sprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. The T. ni colonies resistant to Bacillus thuringiensis serovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca. 20% survival on BollGard II foliage. BollGard II-resistant T. ni strains were established by selection with BollGard II foliage to further remove Cry2Ab-sensitive alleles in the T. ni populations. The BollGard II-resistant strains showed incomplete resistance to BollGard II, with adjusted survival values of 0.50 to 0.78 after 7 days. The resistance to the dual-toxin cotton plants was conferred by two genetically independent resistance mechanisms: one to Cry1Ac and one to Cry2Ab. The 50% lethal concentration of Cry2Ab for the resistant strain was at least 1,467-fold that for the susceptible T. ni strain. The resistance to Cry2Ab in resistant T. ni was an autosomally inherited, incompletely recessive monogenic trait. Results from this study indicate that insect populations under selection by Bt sprays in agriculture can be resistant to multiple Bt toxins and may potentially confer resistance to multitoxin Bt crops.
authors.affiliation: Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Kain
authors.affiliation: Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA.
authors.forename: Xiaozhao
authors.initials: X
authors.lastname: Song
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Alida F
authors.initials: AF
authors.lastname: Janmaat
authors.affiliation: Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA.
authors.forename: Jian-Zhou
authors.initials: JZ
authors.lastname: Zhao
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Judith
authors.initials: J
authors.lastname: Myers
authors.affiliation: Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Shelton
authors.affiliation: Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA pw15@cornell.edu.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
mesh_terms: D000483:Alleles; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000633:toxicity*; D004351:Drug Resistance; D004731:Endotoxins / Q000235:genetics / Q000633:toxicity*; D003368:Gossypium / Q000469:parasitology*; D006460:Hemolysin Proteins / Q000235:genetics / Q000633:toxicity*; D007915:Lepidoptera / Q000187:drug effects* / Q000502:physiology*; D030821:Plants, Genetically Modified; D012641:Selection, Genetic; D016019:Survival Analysis
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis