ABSTRACT

Evolution of resistance to genetically modified Bacillus thuringiensis (Bt) crops in pest populations is a major threat to the sustainability of the technology. Incidents of field resistance that have led to control problems of Bt crops or significantly reduced susceptibility of individual Bt proteins in pyramided plants have increased dramatically across the world, especially in recent years. Analysis of globally published data showed that 61.5% and 60.0% of the cases of resistance with major alleles that allowed homozygous resistant genotypes to survival on Bt crops were functionally non-recessive and did not involve fitness costs, respectively. Dominance levels (D_FLs) measured on Bt plants ranged from −0.02 to 1.56 with a mean (± sem) of 0.35 ± 0.13 for the 13 cases of single-gene resistance to Bt plants that have been evaluated. Among these, all six cases with field control problems were functionally non-recessive with a mean D_FL of 0.63 ± 0.24, which was significantly greater than the D_FL (0.11 ± 0.07) of the seven cases without field resistance. In addition, index of fitness costs (IFC) of major resistance was calculated for each case based on the fitness of resistant (R’R’) and heterozygous (R’S’) genotypes on non-Bt plants divided by the fitness of their susceptible (S’S’) counterparts. The estimated IFCs for 15 cases of single-gene resistance were similar for R’R’ and R’S’, and for the cases with and without field resistance; and the values averaged 1.10 ± 0.12 for R’R’ and 1.20 ± 0.18 for R’S’. Limited published data suggest that resistance of insects to dual/multiple-gene Bt crops is likely to be more recessive than the related single-gene resistance, but their IFCs are similar. The quantitative analysis of the global data documents that the prevalence of non-recessive resistance has played an essential role in the widespread evolution of resistance to Bt crops, while the lack of fitness costs is apparently not as critical as the non-recessive resistance. The results suggest that planting of ‘high dose’ traits is an effective method for Bt crop IRM and more comprehensive management strategies that are also effective for functionally non-recessive resistance should be deployed.

摘要

害虫种群中对转基因苏云金芽孢杆菌(Bt) 作物的抗性进化是对该技术可持续性的主要威胁。导致 Bt 作物控制问题或显着降低金字塔植物中单个 Bt 蛋白敏感性的田间抗性事件在世界范围内急剧增加，尤其是近年来。对全球公布的数据的分析表明，61.5% 和 60.0% 的主要等位基因抗性病例允许纯合抗性基因型在 Bt 作物上存活，在功能上是非隐性的，并且不涉及适应成本。优势水平（D _FLs) 在 Bt 植物上测量的范围从 -0.02 到 1.56，对于已评估的 13 例对 Bt 植物的单基因抗性，平均值 (± sem) 为 0.35 ± 0.13。其中，所有六个有现场控制问题的案例在功能上都是非隐性的，平均 D _FL为 0.63 ± 0.24，显着大于 D _FL(0.11±0.07) 的七种情况下没有场电阻。此外，基于非 Bt 植物上抗性 (R'R') 和杂合 (R'S') 基因型的适应性除以它们的易感性的适应性，计算每种情况的主要抗性的适应性成本 (IFC) 指数。 S'S') 对应。15 例单基因抗性的 IFC 估计值在 R'R' 和 R'S' 以及有和没有田间抗性的情况下相似；R'R' 的平​​均值为 1.10 ± 0.12，R'S' 的平均值为 1.20 ± 0.18。有限的公开数据表明，昆虫对双/多基因 Bt 作物的抗性可能比相关的单基因抗性更隐性，但它们的 IFC 相似。全球数据的定量分析表明，非隐性抗性的盛行在 Bt 作物抗性的广泛演变中发挥了重要作用，而缺乏适应成本显然不如非隐性抗性那么严重。结果表明，种植“高剂量”性状是 Bt 作物 IRM 的有效方法，应该部署对功能性非隐性抗性也有效的更全面的管理策略。