Early Warning of Cotton Bollworm Resistance Associated with Intensive Planting of Bt Cotton in China

• Published in: PloS one Vol. 6; no. 8; p. e22874
• Main Authors: Zhang, Haonan, Yin, Wei, Zhao, Jing, Jin, Lin, Yang, Yihua, Wu, Shuwen, Tabashnik, Bruce E., Wu, Yidong
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.08.2011; Public Library of Science (PLoS)
• Subjects: Agriculture; Agriculture - methods; Agriculture - trends; Animals; Australia; Bacillus thuringiensis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacterial Proteins - toxicity; Bioassays; Biology; China; Confidence intervals; Cotton; Cotton trade; Crop diseases; Crops; Cross-resistance; Cry1Ac toxin; Disease Resistance - genetics; Education; Endotoxins - genetics; Endotoxins - metabolism; Endotoxins - toxicity; Evolution; Exposure; Farmers; Genetic engineering; Genetically modified crops; Gossypium - genetics; Gossypium - parasitology; Helicoverpa armigera; Hemolysin Proteins - genetics; Hemolysin Proteins - metabolism; Hemolysin Proteins - toxicity; Host plants; Host-Parasite Interactions; Insect pests; Insecticide Resistance - drug effects; Insecticides; Insecticides - pharmacology; Insects; Laboratories; Lepidoptera; Moths - growth & development; Moths - physiology; Noctuidae; Pest resistance; Pesticide resistance; Pests; Plant Diseases - genetics; Plant Diseases - parasitology; Plants, Genetically Modified; Plutellidae; Populations; Proteins; Refuges; Surveys; Time Factors; Toxins; Transgenic plants; United States; Australia; United States; China; Hawaii; United States > US; Yangtze River
• DOI: 10.1371/journal.pone.0022874
• ISSN: 1932-6203

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.