Pest Management Science (2010) 66, 155-161

Fengyi Liu, Zhiping Xu, Yu Cheng Zhu, Fangneng Huang, Yanhua Wang, Huiling Li, Hua Li, Congfen Gao, Weijun Zhou and Jinliang Shen (2010)
Evidence of field-evolved resistance to Cry1Ac-expressing Bt cotton in Helicoverpa armigera (Lepidoptera: Noctuidae) in northern China
Pest Management Science 66 (2), 155-161
Abstract: BACKGROUND: Evolution of resistance threatens the continued success of transgenic crops expressing insecticidal proteins. One of the key factors for successful resistance management is the timely implementation of monitoring programmes to detect early changes of resistance allele frequency in field populations. F₁/F₂ screen, dose-response bioassays and field survey were used to monitor resistance to the Cry1Ac-expressing cotton in a field population of Helicoverpa armigera (Hübner), the primary target of transgenic Bt cotton in China.
RESULTS: Field survey showed an increased trend of egg populations of H. armigera on Bt cotton in the Qiuxian area from 2003 to 2007. By using the F₂ screening procedure, the resistance allele frequency in the Qiuxian (Hebei, China) population of H. armigera collected during 2007 was estimated to be 0.075 (95% CI: 0.053-0.100), which was 12 times greater than that estimated 9 years ago. Dose-response bioassay with the field population collected from the same area showed a significant resistance level (11-fold) to Cry1Ac toxin compared to a laboratory susceptible strain.
CONCLUSION: This study documented a case of field-evolved resistance in H. armigera after several years of intensive planting of Bt cotton. Proactive tactics must be adopted to prevent further increase of resistance gene frequency in the Qiuxian region.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Fang Neng Huang, Jin Liang Shen, Congfen Gao

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Helicoverpa armigera	Cotton (Gossypium)	China (NE)
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Helicoverpa armigera	Cotton (Gossypium)	China (NE)