title: Early warning of cotton bollworm resistance associated with intensive planting of Bt cotton in China.
abstract: Transgenic crops producing Bacillus thuringiensis (Bt) toxins kill some key insect pests, but evolution of resistance by pests can reduce their efficacy. The predominant strategy for delaying pest resistance to Bt crops requires refuges of non-Bt host plants to promote survival of susceptible pests. To delay pest resistance to transgenic cotton producing Bt toxin Cry1Ac, farmers in the United States and Australia planted refuges of non-Bt cotton, while farmers in China have relied on "natural" refuges of non-Bt host plants other than cotton. Here we report data from a 2010 survey showing field-evolved resistance to Cry1Ac of the major target pest, cotton bollworm (Helicoverpa armigera), in northern China. Laboratory bioassay results show that susceptibility to Cry1Ac was significantly lower in 13 field populations from northern China, where Bt cotton has been planted intensively, than in two populations from sites in northwestern China where exposure to Bt cotton has been limited. Susceptibility to Bt toxin Cry2Ab did not differ between northern and northwestern China, demonstrating that resistance to Cry1Ac did not cause cross-resistance to Cry2Ab, and implying that resistance to Cry1Ac in northern China is a specific adaptation caused by exposure to this toxin in Bt cotton. Despite the resistance detected in laboratory bioassays, control failures of Bt cotton have not been reported in China. This early warning may spur proactive countermeasures, including a switch to transgenic cotton producing two or more toxins distinct from Cry1A toxins.
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Haonan
authors.initials: H
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Yin
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Lin
authors.initials: L
authors.lastname: Jin
authors.forename: Yihua
authors.initials: Y
authors.lastname: Yang
authors.forename: Shuwen
authors.initials: S
authors.lastname: Wu
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Tabashnik
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000383:Agriculture / Q000379:methods / Q000639:trends; D000818:Animals; D001315:Australia; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity; D002681:China; D060467:Disease Resistance / Q000235:genetics; D004731:Endotoxins / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity; D003368:Gossypium / Q000235:genetics* / Q000469:parasitology; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity; D006790:Host-Parasite Interactions; D007305:Insecticide Resistance / Q000187:drug effects; D007306:Insecticides / Q000494:pharmacology; D009036:Moths / Q000254:growth & development / Q000502:physiology; D010935:Plant Diseases / Q000235:genetics / Q000469:parasitology; D030821:Plants, Genetically Modified; D013997:Time Factors; D014481:United States
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis