转Bt＋CpTI双价基因抗虫棉铃虫性的时空表达

以转单价Bt基因抗虫棉品系中心Bt和常规棉苏棉12号对照，研究了转Bt＋CpTi双抗－1抗虫棉对棉铃虫,抗性的时空表达特征，在棉花生长发育进程中，用4－21叶位主茎叶饲喂棉铃虫初孵幼,虫，5天后观察：双抗－1和中心Bt的4－21叶上存活棉铃虫中均无3龄幼虫，苏棉12号中3龄幼虫存占活幼虫的40％以上，双抗－1和中心B棉铃虫的死亡率相近且随叶位升高而下降，分期播 抗虫性测验与各叶位抗虫性测定相似，即双抗－1和中心Bt各播种期的存活棉铃虫中没有3龄虫，苏棉12号各播种期都有3龄虫出现，双抗-1棉铃虫的死亡率与中心Bt相近，且随播种日期推迟棉铃虫死亡率逐渐升高，试验结果表明：双抗－1对棉铃虫的抗性水平与中心Bt相近，且抗性表现为前期高后期低，也对双价抗虫棉的时空表达特征与棉铃虫产生抗性的风险关系进行了讨论。

Temporary Fluctuation of Resistance of the Transgenic Cotton Harboring Bt+CpTI Double-gene to Helicoverpa armigera

Temporal fluctuation of resistance to bollworm (Helicoverpa armigera) of the transgenic cotton harboring Bt + CpTI double gene was measured using transgenic Bt cotton (Zhongxin Bt) and commercial variety, Sumian 12 as controls. Laboratory bioassay indicated that transgenic cotton showed good efficacy against Helicoverpa armigera. There were no 3rd instar bollworm survived in transgenic double gene cotton and Zhongxin Bt cotton after 5 days fed with the 4th to 21th leaves on main stem, while more than 40% 3rd instar bollworm survived in Sumian 12(CK). However, there was a declind of resistance as plants grew since the mortality (%) of H. armigera decreased gradually. The temporal fluctuation of resistance in these transgenic cotton lines was also demonstrated in laboratory bioassay of leaves simultaneously collected from transgenic plants sown at different times from Mar. 1 to Sept. 19, 1999. The relationship between the insect resistance of transgenic cotton and the possible risk of resistant production in bollworm population to Bt cotton is also discussed.