Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Box 9775, Miss. State, MS 39762, USA.
J Econ Entomol. 2013 Feb;106(1):382-92. doi: 10.1603/ec12203.
Recent Environmental Protection Agency (EPA) decisions regarding resistance management in Bt-cropping systems have prompted concern in some experts that dual-gene Bt-corn (CrylA.105 and Cry2Ab2 toxins) may result in more rapid selection for resistance in Helicoverpa zea (Boddie) than single-gene Bacillus thuringiensis (Bt)-corn (CrylAb toxin). The concern is that Bt-toxin longevity could be significantly reduced with recent adoption of a natural refuge for dual-gene Bt-cotton (CrylAc and Cry2Ab2 toxins) and concurrent reduction in dual-gene corn refuge from 50 to 20%. A population genetics framework that simulates complex landscapes was applied to risk assessment. Expert opinions on effectiveness of several transgenic corn and cotton varieties were captured and used to assign probabilities to different scenarios in the assessment. At least 350 replicate simulations with randomly drawn parameters were completed for each of four risk assessments. Resistance evolved within 30 yr in 22.5% of simulations with single-gene corn and cotton with no volunteer corn. When volunteer corn was added to this assessment, risk of resistance evolving within 30 yr declined to 13.8%. When dual-gene Bt-cotton planted with a natural refuge and single-gene corn planted with a 50% structured refuge was simulated, simultaneous resistance to both toxins never occurred within 30 yr, but in 38.5% of simulations, resistance evolved to toxin present in single-gene Bt-corn (CrylAb). When both corn and cotton were simulated as dual-gene products, cotton with a natural refuge and corn with a 20% refuge, 3% of simulations evolved resistance to both toxins simultaneously within 30 yr, while 10.4% of simulations evolved resistance to CrylAb/c toxin.
最近美国环境保护署 (EPA) 有关 Bt 种植系统抗药性管理的决定引起了一些专家的担忧，他们担心双基因抗虫玉米（Cry1A.105 和 Cry2Ab2 毒素）可能比单基因苏云金芽孢杆菌 (Bt) 玉米 (Cry1Ab 毒素) 更快地导致斜纹夜蛾 (Helicoverpa zea (Boddie)) 产生抗药性。人们担心，随着双基因抗虫棉（Cry1Ac 和 Cry2Ab2 毒素）天然避难所的最近采用以及双基因玉米避难所从 50%减少到 20%，Bt 毒素的寿命可能会显著缩短。应用模拟复杂景观的种群遗传学框架进行风险评估。捕获了几位转基因玉米和棉花品种的专家意见，并将其用于评估中不同情况的概率分配。对于四个风险评估中的每一个，都完成了至少 350 次随机参数的复制模拟。在没有自愿种植玉米的情况下，单基因玉米和棉花的模拟中，抗药性在 30 年内进化的情况占 22.5%。当将这种评估增加自愿种植玉米的情况时，抗药性在 30 年内进化的风险下降到 13.8%。当模拟种植带有天然避难所的双基因抗虫棉和种植带有 50%结构化避难所的单基因玉米时，两种毒素的同时抗性在 30 年内从未发生过，但在 38.5%的模拟中，对单基因 Bt 玉米（Cry1Ab）中存在的毒素产生了抗药性。当玉米和棉花都被模拟为双基因产品时，棉花带有天然避难所，玉米带有 20%的避难所，在 30 年内有 3%的模拟对两种毒素同时产生抗性，而 10.4%的模拟对 Cry1Ab/c 毒素产生抗性。
