title: Inheritance of field-relevant resistance to the Bacillus thuringiensis protein Cry1Ac in Pectinophora gossypiella (Lepidoptera: Gelechiidae) collected from India.
abstract: BACKGROUND
  The inheritance and phenotypic expression of resistance to Bacillus thuringiensis Cry1Ac insecticidal protein were studied in selected populations of pink bollworm, Pectinophora gossypiella (Saunders), that were collected from Bollgard cotton in India. The individual populations in the pool were Cry1Ac resistant and sourced from Cry1Ac-containing Bt cotton (Bollgard) hybrids in 2010.
  
  
  RESULTS
  Laboratory selection on diet with 1.0 µg Cry1Ac protein mL(-1) increased the percentage reaching at least third instar from 7% in the F3 generation to 94% in the F15 generation, a 257-fold increase in median lethal concentration relative to the susceptible strain. Analysis of reciprocal genetic crosses between the Cry1Ac-resistant strain NKJ and a susceptible laboratory strain MRC showed a dominance of 0.22, indicating that the inheritance of Cry1Ac resistance is partially recessive at Cry1Ac concentrations comparable with those in Bollgard. Analyses of backcrosses of F1 hybrid moths with NKJ and MRC indicated that resistance is autosomal. The Cry1Ac-resistant strain exhibited little or no cross-resistance to the Cry2Ab2 protein.
  
  
  CONCLUSIONS
  This is the first study of the dominance of Cry1Ac field resistance in P. gossypiella. The results provide the basis for refining resistance management strategies for Bt cotton.
authors: Monsanto Research Centre, Bangalore, Karnataka, India.
authors: Rupa
authors: R
authors: Nair
authors: Monsanto Research Centre, Bangalore, Karnataka, India.
authors: Subray P
authors: SP
authors: Kamath
authors: Monsanto Research Centre, Bangalore, Karnataka, India.
authors: Komarlingam S
authors: http://orcid.org/0000-0002-0329-0483
authors: KS
authors: Mohan
authors: Monsanto Company, St Louis, MO, USA.
authors: Graham
authors: G
authors: Head
authors: Monsanto Company, St Louis, MO, USA.
authors: Douglas V
authors: DV
authors: Sumerford
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D004731:Endotoxins / Q000494:pharmacology*; D006460:Hemolysin Proteins / Q000494:pharmacology*; D040941:Heredity; D007194:India; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D009036:Moths / Q000187:drug effects* / 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: Bollgard; Cry1Ac; Cry2Ab2; Pectinophora gossypiella; insect resistance; transgenic cotton