title: Sensitivity analysis of a spatially-explicit stochastic simulation model of the evolution of resistance in Helicoverpa zea (Lepidoptera: Noctuidae) to Bt transgenic corn and cotton.
abstract: The sensitivities of a model simulating the evolution of resistance in Helicoverpa zea to Bt toxins in transgenic crops were investigated by examining effects of each of the model parameters on the frequency of resistance alleles after 8 yr. The functional dominance of resistance alleles and the initial frequency of those alleles had a major impact on resistance evolution. The survival of susceptible insects on the transgenic crops and the population dynamics of the insect, driven by winter survival and reproductive rates, were also important. In addition, agricultural practices including the proportion of the acreage planted to corn, and the larval threshold for spraying cotton fields affected the R-allele frequency. Many of these important parameters are inherently variable or cannot be measured with accuracy, so model output cannot be interpreted as being a forecast. However, this analysis is useful in focusing empirical research on those aspects of the insects' life system that have the largest effects on resistance development, and indicates ways in which to improve products and agricultural practices to increase the expected time to resistance. The model can thus be used as a scientific basis for devising a robust resistance management strategy for Bt crops.
authors.affiliation: Department of Entomology, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC 27695, USA. nstorer@dow.com
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Storer
authors.forename: Steven L
authors.initials: SL
authors.lastname: Peck
authors.forename: Fred
authors.initials: F
authors.lastname: Gould
authors.forename: John W
authors.initials: JW
authors.lastname: Van Duyn
authors.forename: George G
authors.initials: GG
authors.lastname: Kennedy
mesh_terms: D000383:Agriculture; D000483:Alleles; D000818:Animals; D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics*; D003198:Computer Simulation; D004463:Ecology; D004731:Endotoxins / Q000235:genetics; D019143:Evolution, Molecular; D015870:Gene Expression; D003368:Gossypium / Q000235:genetics*; D006460:Hemolysin Proteins; D007305:Insecticide Resistance / Q000235:genetics*; D007814:Larva / Q000254:growth & development; D009036:Moths / Q000235:genetics* / Q000254:growth & development; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified; D012680:Sensitivity and Specificity; D003313:Zea mays / Q000235:genetics*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis