Gao Yulin, Wu Kongming, Gould Fred
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, China.
Environ Entomol. 2009 Aug;38(4):1336-42. doi: 10.1603/022.038.0445.
Helicoverpa armigera is an important lepidopteran pest of cotton in China. From 2002, the frequency of Bt resistance alleles and quantitative shifts in larval Cry1Ac tolerance of field H. armigera population were monitored using bioassays of F(1) and F(2) offspring of isofemale lines from Xiajin County of Shandong Province (an intensive Bt cotton planting area) and Anci County of Hebei Province (a multiple-crop system including corn, soybean, peanut, and Bt cotton) in northern China. During 2006-2008, a total of 2,306 isofemale lines from the Xiajin population and a total of 1,270 isofemale lines from the Anci population were successfully screened on Cry1Ac diets. For each year, it was estimated that the major resistance gene frequency in Xiajin population in 2006, 2007, and 2008 was 0, 0.00022, and 0.00033, respectively. No major alleles conferring resistance to Cry1Ac were found in the Anci population; the frequency of resistance alleles for Cry1Ac was 0. Based on the relative average development rates (RADRs) of H. armigera larvae in F(1) tests, no substantial increase in Cry1Ac tolerance was found in either location over the 3-yr period. There were also significantly positive correlations between RADR of lines in the F(1) generation and the RADR of their F(2) offspring, indicating genetic variation in response to toxin. The low frequency of resistance alleles found in this study and in our previous results from 2002 to 2005 suggest the frequency of resistance alleles has remained low and that natural refugia resistance management strategy maybe effective for delaying resistance evolution in H. armigera to Bt cotton in northern China.
棉铃虫是中国棉花的一种重要鳞翅目害虫。从2002年起，利用来自中国北方山东省夏津县（Bt棉花密集种植区）和河北省安次县（包括玉米、大豆、花生和Bt棉花的多作物种植系统）的同雌系F(1)和F(2)后代的生物测定法，监测了田间棉铃虫种群中Bt抗性等位基因的频率以及幼虫对Cry1Ac耐受性的定量变化。在2006 - 2008年期间，共成功筛选了来自夏津种群的2306个同雌系和来自安次种群的1270个同雌系在含Cry1Ac的饲料上进行测试。对于每年，估计2006年、2007年和2008年夏津种群中的主要抗性基因频率分别为0、0.00022和0.00033。在安次种群中未发现赋予对Cry1Ac抗性的主要等位基因；Cry1Ac抗性等位基因的频率为0。基于F(1)测试中棉铃虫幼虫的相对平均发育率（RADRs），在这两个地点的3年期间均未发现Cry1Ac耐受性有实质性增加。F(1)代品系的RADR与其F(2)后代的RADR之间也存在显著正相关，表明对毒素的反应存在遗传变异。本研究以及我们之前2002年至2005年的结果中发现的抗性等位基因低频表明抗性等位基因频率一直较低，并且自然避难所抗性管理策略可能有效地延缓了中国北方棉铃虫对Bt棉花的抗性进化。
