title: Evolution of Resistance by Helicoverpa zea (Lepidoptera: Noctuidae) Infesting Insecticidal Crops in the Southern United States.
abstract: We created a deterministic, frequency-based model of the evolution of resistance by corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), to insecticidal traits expressed in crops planted in the heterogeneous landscapes of the southern United States. The model accounts for four generations of selection by insecticidal traits each year. We used the model results to investigate the influence of three factors on insect resistance management (IRM): 1) how does adding a third insecticidal trait to both corn and cotton affect durability of the products, 2) how does unstructured corn refuge influence IRM, and 3) how do block refuges (50% compliance) and blended refuges compare with regard to IRM? When Bt cotton expresses the same number of insecticidal traits, Bt corn with three insecticidal traits provides longer durability than Bt corn with two pyramided traits. Blended refuge provides similar durability for corn products compared with the same level of required block refuge when the rate of refuge compliance by farmers is 50%. Results for Mississippi and Texas are similar, but durabilities for corn traits are surprisingly lower in Georgia, where unstructured corn refuge is the highest of the three states, but refuge for Bt cotton is the lowest of the three states. Thus, unstructured corn refuge can be valuable for IRM but its influence is determined by selection for resistance by Bt cotton.
authors.forename: Zaiqi
authors.initials: Z
authors.lastname: Pan
authors.forename: David
authors.initials: D
authors.lastname: Onstad
authors.forename: Philip
authors.initials: P
authors.lastname: Crain
authors.forename: Andre
authors.initials: A
authors.lastname: Crespo
authors.forename: William
authors.initials: W
authors.lastname: Hutchison
authors.forename: David
authors.initials: D
authors.lastname: Buntin
authors.forename: Pat
authors.initials: P
authors.lastname: Porter
authors.forename: Angus
authors.initials: A
authors.lastname: Catchot
authors.forename: Don
authors.initials: D
authors.lastname: Cook
authors.forename: Clint
authors.initials: C
authors.lastname: Pilcher
authors.forename: Lindsey
authors.initials: L
authors.lastname: Flexner
authors.forename: Laura
authors.initials: L
authors.lastname: Higgins
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D005075:Biological Evolution; D018556:Crops, Agricultural / Q000235:genetics; D004731:Endotoxins; D006460:Hemolysin Proteins; D007305:Insecticide Resistance / Q000235:genetics; D008957:Models, Genetic; D009036:Moths / Q000235:genetics*; D030821:Plants, Genetically Modified; D015144:Southeastern United States
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis