Bt作物的昆虫抗药性管理(1)

1、Insect Resistance Management for Bt CropsBt作物的昆虫抗药性管理作物的昆虫抗药性管理Tessa Milofsky, M.S. and Sharlene Matten, Ph.D.泰莎. 米洛夫斯基 硕士沙利恩.马顿 博士U.S. Environmental Protection Agency Office of Pesticide Programs美国环保局 杀虫剂项目办公室1IRM: what is it?昆虫抗药性管理定义昆虫抗药性管理定义Insect resistance management (IRM) is a strategy to mit

2、igate the development of insects resistant to a pesticide (e.g., resistance to Bacillus thuringiensis or Bt) 昆虫抗药性管理(IRM)是为了减轻害虫对杀虫剂(例如对BT)产生抗性而采取的一种策略.2IRM: why is it important?IRM的重要性的重要性lMaintaining the efficacy of Bt, a low-risk pesticide, is beneficial for the following reasons:l维持低风险杀虫剂维持低风险杀虫

3、剂Bt的功效有如下的优点的功效有如下的优点:Bt replaces higher risk pesticidesBt杀虫剂可以代替其他高风险性的杀虫剂Less exposure of nontarget organisms to superficially applied pesticides降低非目标生物暴露于杀虫剂的可能性Use of Bt crops may provide greater profits to farmers, due to reduced use of insecticides由于减少了杀虫剂的使用,Bt作物可以给农民带来更大的收益3Critical componen

4、ts of IRM planIRM计划的重要组成成分计划的重要组成成分lPest biology 害虫生物学lDose 剂量lCross-resistance 抗性转移lRefuge 避难所lModeling 建立模型lResistance monitoring 抗性监测lRemedial action 矫正措施lCompliance assurance 确保规范性lGrower education 种植者教育4Pest biology害虫生物学害虫生物学lImportant factors include:Number of insect generations per yearHost r

5、angeInsect movement and dispersal patternsMating and ovipositional behaviorPopulation dynamicsl要点包括:每年害虫繁殖的代数宿主的范围害虫移动和分布的模式交配和产卵行为种群动态5Pest biology: an example害虫生物学举例害虫生物学举例lEuropean corn borer (ECB), Ostrinia nubilalis1-4 generations per yearPolyphagous (prefers corn)Movement:lLarvae - can move fr

6、om plant-to-plant within a fieldlAdults - mostly local movement, but some long distance migratory movement can occurl欧洲玉米螟(ECB)每年繁殖1-4代杂食性(偏好玉米)移动l幼虫可以在同一田地内不同植株上移动l成虫大部分在本地活动,但也有可能进行长距离迁移Female雌性雌性Male雄性雄性late instars晚期幼虫晚期幼虫ECB6Dose 剂量剂量lDose = the amount of toxin expressed over time by a transgen

7、ic crop, relative to the susceptibility of a target pest; can be determined through field efficacy trials or laboratory bioassaysl剂量=转基因作物在一定时间内表达的毒素的量, 和目标害虫的敏感性相关; 通常由田间功效实验或实验室生物测试所决定.lHigh dose = at least 25x the amount of toxin needed to kill all susceptible target insects; preferred over low d

8、ose events for refuge-based IRM strategiesl高剂量=至少为杀死所有敏感目标害虫剂量的25倍; 在以避难所为基础的昆虫抗性管理策略中，使用高剂量遗传事件体要比低剂量遗传事件体好7Dose assumptions剂量假设剂量假设lThree genotypes for resistance/susceptibility (SS, rS, rr)lResistance (rr) is recessive and rarelRefuge supplies SS (homozygous susceptible) genotypelRandom mating:rr

9、 x SS rSrS x SS rS or SSlSS and rS susceptible to high dosel三种抗性三种抗性/敏感性基因型敏感性基因型(SS,rS,rr)l抗性基因抗性基因(rr)是隐性的是隐性的,少见的少见的l安全基因型安全基因型SS(纯合敏感纯合敏感)l随机交配随机交配:rr x SS rSrS x SS rS or SSlSS和和rS对高剂量敏感对高剂量敏感LC500100低高8Dose levels: some examples关于剂量水平的一些例子关于剂量水平的一些例子lLepidopteran-active corn (Cry1Ab & Cry1

10、F):High doselEuropean corn borer (ECB), Ostrinia nubilalislSouthwestern corn borer (SWCB) Diatraea crambidoidesNon-high doselCorn earworm (CEW), Helicoverpa zeal鳞翅目敏感玉米 (Cry1Ab & Cry1F):高剂量l欧洲玉米螟 (ECB), Ostrinia nubilalisl西南玉米螟 (SWCB) Diatraea crambidoides非高剂量l玉米棉铃虫 (CEW), Helicoverpa zeaWCRfema

11、lemalelate instarsECB9Dose levels: some examples关于剂量水平的一些例子关于剂量水平的一些例子lRootworm-active corn (Cry3Bb1, Cry34/35, mCry3A)Non-high doselWestern corn rootworm (WCR), Diabrotica virgifera virgiferalNorthern corn rootworm (NCR), D. barberilMexican corn rootworm (MCR), D. virgifera zealSecondary pestsNon-h

12、igh dose for some pestsl根虫敏感玉米 (Cry3Bb1, Cry34/35, mCry3A)非高剂量l西部玉米根虫 (WCR), Diabrotica virgifera virgiferal北部玉米根虫 (NCR), D. barberil墨西哥玉米根虫 (MCR), D. virgifera zeal次级害虫非高剂量WCRfemalemalelate instarsECB10Cross-resistance抗性转移抗性转移lWhen resistance to a single Bt toxin confers pest resistance to a cluste

13、r of related toxins lFactors affecting cross-resistance include:Similarity/dissimilarity of commercialized toxinsUse of single toxin versus multiple toxinsLevel of resistance in an insect populationl害虫对单一Bt蛋白的抗性使得害虫对其他一系列相关毒素都产生抗性l影响抗性转移的因素包括:商品用毒素的异同点单一毒素和复合毒素的使用昆虫种群的抗性水平11Cross-resistance: an exam

14、ple(抗性转移抗性转移:举例说明举例说明)lBinding site diagram for European corn borer(欧洲玉米螟结合位点简图)Cry1AbCry1FCry1Ac220 KDaCadherin154 KDaAPN145/167 KDa APNOtherEuropean corn borer (based on Hua, G., Masson, L., Jurat-Fuentes, J. L., Schwab, G., Adang, M. J. 2001. Binding analyses of Bacillus thuringiensis Cry d-endot

15、oxins using brush border membrane vesicles of Ostrinia nubilalis. Appl. Env. Microbiol. 67: 872-879)(其他)12Refuge 避难所避难所Any host plant that does not produce Bt toxin and has not been treated with conventional Bt formulations (may be treated with non-Bt insecticide)任何不产生Bt毒素并且也未经常规Bt杀虫剂处理过的宿主植物(可能经非Bt

16、杀虫剂处理过)Enables mating between resistant and susceptible adults, resulting in production of susceptible offspring抗性和敏感性成熟植株杂交可以产生敏感性的后代13Refuge options避难所的选择避难所的选择lStructured refuge = specified size, location in relation to Bt field, and crop/plant compositionlCommunity-based refuge = neighboring gro

17、wers establish shared structured refugelUnstructured or natural refuge = use of alternative host plants/crops in place of defined refugel结构避难所=特定大小,并且位置和Bt植物种植区有一定关系的区域,此区域既有农作物,又有植被l以社区为基础的避难所=相邻的种植者建立的一种共享的结构避难所l非结构或称天然避难所=用一种寄主植物和作物互相交替种植的模式来代替人为限定的避难所模式14Refuge options避难所的选择避难所的选择lSeed bag mix =

18、 Bt seed bags contain Bt seed and non-Bt seed (e.g., 80% Bt, 20% non-Bt); seed may be bagged separately or mixed togetherlRegional limit = national/regional government enforced limit on Bt seed sales (e.g., 80% in defined region) l混装种袋=在这种含Bt种子的袋子中既含有Bt种子,也含有非Bt种子(例如:80%Bt种子, 20%非Bt种子), 种子可以先按小袋分装好再

19、混和,也可以直接混在一起.l区域限制=国家或地方政府对Bt种子的买卖进行严格限制(例如: 在一定区域内，只允许80%的Bt种子的买卖)15Seed mixBlockIn-field strips田地内的条带模式Internal block(s)内部种植模式Border (block)周边种植模式Structured refuge options结构避难所的选择结构避难所的选择External block外部种植模式种子混和16Other refuge options其他避难所选择其他避难所选择Community refuge社区避难所模式80% Bt seed corn玉米种子20% non-

20、Bt seed corn玉米种子Natural refuge天然避难所Bt cottonBt棉花 w/ TBWSoybean大豆Tobacco烟草Tobacco budworm, 烟草蚜虫Heliothis virescens 17Bt corn refuge specifications: an exampleBt玉米避难所规范示例玉米避难所规范示例l20% refuge required in corn belt; 50% refuge required in corn/cotton regionlStructured refuge is required. Refuges may be

21、planted in one of the following designs:In-field strips (4-6 rows)Blocks (internal or external)lRefuge requirements are the same for lepidopteran and coleopteran active productsl在Bt玉米田中20%为避难所,在玉米/棉花田中则为50%l结构性避难所是必须的.避难所可以按如下的设计来耕作:田地内条带(4-6行)内部或外部田块18Modeling 模拟模拟lUseful tool for predicting the li

22、kelihood of resistance, for evaluating the durability of IRM strategies, and for helping to focus data needs. Model components include:Biological information (pest biology, population dynamics)Genetics (R-allele dominance/frequency, cross resistance)Operational aspects (dose, single/stacked toxin(s)

23、, refuge)l建立模型是预测抗药可能性,评价IRM策略持久性和帮助调整数据需求的一种有效方法. 模型包括以下组成成分:生物信息(害虫生物学,种群动态)遗传学(R-等位基因显性/频率, 抗性转移)运行情况(剂量,单一的/叠加的毒剂,避难所)19Resistance monitoring抗性监测抗性监测lCan help to prolong the efficacy of an insect resistant croplDesigned to detect resistance 2-3 years before field failurelTarget pest sampling con

24、sists of:Grower reports of unexpected pest damage in insect-protected crop fieldsRandom population sampling:lSampling based on pest prevalence in regionlSampling target: number of insects needed to determine resistance at p0.01 l可以延长抗虫作物的功效l可以在失效前监测抗性2-3年l目标害虫取样包括:种植者在抗虫作物区域内由害虫造成的意外损失报告随机种群取样:l害虫流行

25、区域取样l取样目标:用来确定抗性所需的害虫数量(p0.01)20Resistance monitoring (cont.)抗性监测抗性监测(续续)lBioassays are used to detect potential resistance in sampled populations. Assays include:Pest susceptibility (LC50)Discriminating Dose (LC99)F2 screenlConfirmation studies are used to verify resistance. Questions include:Is th

26、ere field failure? Is the insect resistance trait expressed? Is insect resistance trait inherited?l用生物鉴定来检测样品种群中的潜在抗性. 生物鉴定包括:害虫敏感性鉴定(LC50)差异剂量(LC99)F2筛选l确认研究用来核实抗性.包括:区域失效了么?抗性特征表达了么?抗性性可遗传么?21Resistance monitoring: positive hits for Bt corn in the US? 抗性监测抗性监测: 美国美国Bt玉米正采样数玉米正采样数lIn 2001, mortalit

27、y for one European corn borer (ECB) population (Kandiyohi, MN) was 99% in Cry1Ab discriminating dose assaylFollow-up tests with Bt plant material revealed that population was not field resistantlNo field resistance confirmed for any monitored Bt corn pest l2001年在Cry1Ab不同剂量分析中, 欧洲玉米螟种群的死亡率小于99%lBt作物的

28、后续测试表明种群并没有田间抗药性l被监测的Bt玉米害虫没有被证实产生田间抗药性22Remedial action plan矫正措施矫正措施If resistance is confirmed through resistance monitoring, a remedial action plan is implemented to contain or slow the spread of resistant pest populations 如果抗性监测确认了抗药性, 矫正措施可以减缓害虫种群抗药性的传播23Remedial action plan: an example矫正措施举例矫正措

29、施举例lEPAs plan includes:Mandatory reporting of suspected resistanceUse of alternate control measures in affected areasIncreased resistance monitoringSuspension of Bt crop sales in affected areasInvestigation of cause of resistancel美国环保局措施包括:强制要求对有怀疑的抗药性表现上报在有影响区域使用其他管理措施增强抗性监测在被影响区域终止Bt玉米销售对抗药性原因进行调查

30、24Compliance assurance确保规范性确保规范性Compliance measures implemented to ensure that growers comply with approved IRM program 规范操作可以确保种植者按照害虫抗药性管理规则执行耕种操作.25Compliance assurance: an example确保规范性举例确保规范性举例lEPA requires registrants to implement the following measures:Contracts affirming grower agreement to c

31、omply with approved IRM strategy3rd party grower surveys of IRM implementationOn-farm field visits to verify IRM implementationTips and complaints on non-compliersSuspension of seed access for non-compliersl美国环保局规定登记者必须实施以下方法:合同规定种植者必须遵守IRM策略第三方对IRM执行情况进行调查田间观察以确定IRM的执行情况揭发和投诉不遵守规则的种植者对不遵守规则的种植者终止种子

32、供应26Grower education种植者教育种植者教育Education about the need for IRM, how to implement requirements, and grower responsibility in complying with IRM requirements 对IRM策略的必要性, 怎样完成要求, 和种植者对完成IRM要求所担负的责任进行教育27Summary of EPAs IRM requirements for lepidopteran-active Bt corn美国环保局对鳞翅目昆虫敏感的美国环保局对鳞翅目昆虫敏感的Bt玉米玉米IR

33、M要求概述要求概述l20% refuge in corn belt; 50% refuge in cotton beltlStructured refuge required. Refuges planted in one of the following designs:in-field strips (4-6 rows)blocks (internal or external)lIndustry-wide collaboration on compliance surveysl在玉米种植带中20%为避难所; 在棉花种植带中为50%l结构性避难所是必需的.避难所种植需为如下设计中的一种:田间

34、条带(4-6 行)田块(内部或外部)l广泛合作开展规范性调查28Summary of EPAs IRM requirements for lepidopteran-active Bt corn (cont.)对鳞翅目昆虫敏感的对鳞翅目昆虫敏感的Bt玉米玉米IRM要求概述要求概述(续续)lIndustry-wide uniformity of:Grower agreementsGrower trainingImplementation of tips and complaints l以下行为保持高度一致性:种植者协议种植者培训监测和投诉的实施29Summary of EPAs IRM requi

35、rements for lepidopteran-active Bt corn (cont.)对鳞翅目昆虫敏感的对鳞翅目昆虫敏感的Bt玉米玉米IRM要求概述要求概述(续续)Annual reporting requirements: Compliance assurance (e.g., surveys, grower contracts) Changes to grower education Resistance monitoring data Sales datal年度报告需要:规范性确认材料(例如调查,种植者合同)种植者教育的变化抗性监测数据销售数据30Data sources for

36、 EPAs IRM program美国环保局美国环保局IRM项目的数据来源项目的数据来源lPublished scientific literaturelIndustry submissionslExperts (academia, government, industry)lMeetings (advisory panels, workshops, ESA, NC205, NC46)lField visitsl已出版的科学文献l工业企业的报告l专家(学术界,政府,工业界)l会议(顾问团,研讨会,ESA,NC205,NC46)l田间观察31Keys to success at EPA美国环保局美国环保局(EPA)取得成功的关键取得成功的关键lEPA is responsive to new scientific informationlEPA seeks scientific input from state and federal agencies, academic experts, and public interest groupslEPA 对最新的科技信息反应积极lEPA 从各州和联邦的政府部门,学术专家和公众团体中寻求科技力量32Keys to success at EPA美国环保局美国环