title: Dominance of Cry1F resistance in Spodoptera frugiperda (Lepidoptera: Noctuidae) on TC1507 Bt maize in Brazil.
abstract: BACKGROUND
  Dominance of resistance has been one of the major parameters affecting the rate of evolution of resistance to Bt crops. High dose is the capacity of Bt crops to kill heterozygous insects and has been an essential component of the most successful strategy to manage resistance to these crops. Experiments were conducted to evaluate directly and indirectly whether the TC1507 event is high dose to Spodoptera frugiperda (JE Smith).
  
  
  RESULTS
  About 8% of heterozygote neonate larvae were able to survive, complete larval development and emerge as normal adults on TC1507 leaves, while susceptible larvae could not survive for 5 days. The estimated dominance of resistance was 0.15 ± 0.09 and significantly higher than zero; therefore, the resistance to Cry1F expressed in TC1507 was not completely recessive. A 25-fold dilution of TC1507 maize leaf tissue in an artificial diet was able to cause a maximum mortality of only 37%, with growth inhibition of 82% at 7 days after larval infestation.
  
  
  CONCLUSIONS
  Resistance to Cry1F in TC1507 maize is incompletely recessive in S. frugiperda. TC1507 maize is not high dose for S. frugiperda. Additional or alternative resistance management strategies, such as the replacement of single-trait Bt maize with pyramided Bt maize, which produces multiple proteins targeting the same insect pests, should be implemented wherever this technology is in use and S. frugiperda is the major pest.
authors.affiliation: Department of Entomology and Acarology, University of São Paulo (ESALQ/USP), Piracicaba, São Paulo, Brazil.
authors.forename: Juliano R
authors.initials: JR
authors.lastname: Farias
authors.affiliation: Department of Entomology, University of Minnesota, St Paul, MN, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Andow
authors.affiliation: Department of Entomology and Acarology, University of São Paulo (ESALQ/USP), Piracicaba, São Paulo, Brazil.
authors.forename: Renato J
authors.initials: RJ
authors.lastname: Horikoshi
authors.affiliation: Department of Entomology and Acarology, University of São Paulo (ESALQ/USP), Piracicaba, São Paulo, Brazil.
authors.forename: Rodrigo J
authors.initials: RJ
authors.lastname: Sorgatto
authors.affiliation: Dow AgroSciences LLC, Indianapolis, IN, USA.
authors.forename: Antonio C
authors.initials: AC
authors.lastname: dos Santos
authors.affiliation: Department of Entomology and Acarology, University of São Paulo (ESALQ/USP), Piracicaba, São Paulo, Brazil.
authors.forename: Celso
authors.initials: C
authors.lastname: Omoto
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D001938:Brazil; D004731:Endotoxins / Q000494:pharmacology*; D006460:Hemolysin Proteins / Q000494:pharmacology*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics; D018411:Spodoptera / Q000187:drug effects* / Q000254:growth & development; D003313:Zea mays / Q000235:genetics*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bacillus thuringiensis; TC1507; fall armyworm; high-dose; recessive; resistance management