title: Baseline Susceptibility of Field Populations of Helicoverpa armigera to Bacillus thuringiensis Vip3Aa Toxin and Lack of Cross-Resistance between Vip3Aa and Cry Toxins.
abstract: The cotton bollwormHelicoverpa armigera(Hübner) is one of the most damaging cotton pests worldwide. In China, control of this pest has been dependent on transgenic cotton producing a singleBacillus thuringiensis(Bt) protein Cry1Ac since 1997. A small, but significant, increase inH. armigeraresistance to Cry1Ac was detected in field populations from Northern China. Since Vip3Aa has a different structure and mode of action than Cry proteins, Bt cotton pyramids containing Vip3Aa are considered as ideal successors of Cry1Ac cotton in China. In this study, baseline susceptibility ofH. armigerato Vip3Aa was evaluated in geographic field populations collected in 2014 from major cotton-producing areas of China. The LC50values of 12 field populations ranged from 0.053 to 1.311 μg/cm², representing a 25-fold range of natural variation among populations. It is also demonstrated that four laboratory strains ofH. armigerawith high levels of resistance to Cry1Ac or Cry2Ab have no cross-resistance to Vip3Aa protein. The baseline susceptibility data established here will serve as a comparative reference for detection of field-evolved resistance to Vip3Aa inH. armigeraafter future deployment of Bt cotton pyramids in China.
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. weiyiyun1988@163.com.
authors.forename: Yiyun
authors.initials: Y
authors.lastname: Wei
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. swwu@njau.edu.cn.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Wu
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. yhyang@njau.edu.cn.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Yang
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. wyd@njau.edu.cn.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000633:toxicity*; D004731:Endotoxins / Q000633:toxicity; D006460:Hemolysin Proteins / Q000633:toxicity; D007814:Larva / Q000187:drug effects*; D007928:Lethal Dose 50; D009036:Moths / Q000187:drug effects*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C447139:Vip3A protein, Bacillus thuringiensis; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Cry1Ac; Cry2Ab; Helicoverpa armigera; Vip3Aa; cross-resistance; susceptibility