title: Baseline sensitivity of maize borers in India to the Bacillus thuringiensis insecticidal proteins Cry1A.105 and Cry2Ab2.
abstract: BACKGROUND
  Among the major pests of maize in India are two stem borers, Chilo partellus (Swinhoe) and Sesamia inferens (Walker), and an earworm, Helicoverpa armigera (Hübner). As a pest control strategy, transgenic Bacillus thuringiensis (Bt) maize hybrids are undergoing regulatory trials in India. We have determined the sensitivity of the target lepidopterans to the insecticidal Bt proteins expressed in Bt maize, as this determines product efficacy and the resistance management strategy to be adopted. Maize hybrids with event MON89034 express two insecticidal Bt proteins, Cry1A.105 and Cry2Ab2.
  
  
  RESULTS
  Sensitivity profiles of 53 populations of C. partellus, 21 populations of S. inferens and 21 populations of H. armigera, collected between 2008 and 2013 from maize-growing areas in India, to Cry1A.105 and Cry2Ab2 proteins were generated through dose-response assays. Cry1A.105 protein was the most effective to neonates of C. partellus (mean MIC90 range 0.30-1.0 µg mL(-1) ) and H. armigera (mean MIC90 range 0.71-8.22 µg mL(-1) ), whereas Cry2Ab2 (mean MIC90 range 0.65-1.70 µg mL(-1) ) was the most effective to S. inferens.
  
  
  CONCLUSIONS
  Populations of C. partellus, S. inferens and H. armigera were susceptible to the Bt proteins Cry1A.105 and Cry2Ab2. The Bt sensitivity data will serve as precommercialisation benchmarks for resistance monitoring purposes.
authors.affiliation: National Bureau of Agriculturally Important Insects, Hebbal, Bangalore, India.
authors.forename: Sushil K
authors.identifier: http://orcid.org/0000-0002-0329-0483
authors.initials: SK
authors.lastname: Jalali
authors.affiliation: National Bureau of Agriculturally Important Insects, Hebbal, Bangalore, India.
authors.forename: Lalitha
authors.initials: L
authors.lastname: Yadavalli
authors.affiliation: National Bureau of Agriculturally Important Insects, Hebbal, Bangalore, India.
authors.forename: Rakshit
authors.initials: R
authors.lastname: Ojha
authors.affiliation: Directorate of Maize Research, Pusa Campus, New Delhi, India.
authors.forename: Pradyumn
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Directorate of Maize Research, Pusa Campus, New Delhi, India.
authors.forename: Suby B
authors.initials: SB
authors.lastname: Sulaikhabeevi
authors.affiliation: Directorate of Maize Research, Pusa Campus, New Delhi, India.
authors.forename: Reema
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Monsanto Research Centre, Bangalore, India.
authors.forename: Rupa
authors.initials: R
authors.lastname: Nair
authors.affiliation: Monsanto Research Centre, Bangalore, India.
authors.forename: Ravi C
authors.initials: RC
authors.lastname: Kadanur
authors.affiliation: Monsanto Research Centre, Bangalore, India.
authors.forename: Subray P
authors.initials: SP
authors.lastname: Kamath
authors.affiliation: Monsanto Research Centre, Bangalore, India.
authors.forename: Mohan S
authors.initials: MS
authors.lastname: Komarlingam
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D018556:Crops, Agricultural / Q000254:growth & development; D004731:Endotoxins / Q000494:pharmacology*; D006460:Hemolysin Proteins / Q000494:pharmacology*; D007194:India; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D008675:Metamorphosis, Biological / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D009036:Moths / Q000187:drug effects* / Q000254:growth & development; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development; D012016:Reference Values; D003313:Zea mays / 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: Bt proteins; Cry1A.105; Cry2Ab2; Indian maize lepidopteran pests; moult inhibitory concentrations; susceptibility