Bt作物的昆虫抗药性管理

Bt作物的昆虫抗药性管理2024/3/13Bt作物的昆虫抗药性管理IRM:whatisit?

昆虫抗药性管理定义 Insectresistancemanagement(IRM)isastrategytomitigatethedevelopmentofinsectsresistanttoapesticide(e.g.,resistancetoBacillusthuringiensisorBt)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.2Bt作物的昆虫抗药性管理IRM:whyisitimportant?

IRM的重要性MaintainingtheefficacyofBt,alow-riskpesticide,isbeneficialforthefollowingreasons:维持低风险杀虫剂Bt的功效有如下的优点:BtreplaceshigherriskpesticidesBt杀虫剂可以代替其他高风险性的杀虫剂Lessexposureofnontargetorganismstosuperficiallyappliedpesticides降低非目标生物暴露于杀虫剂的可能性UseofBtcropsmayprovidegreaterprofitstofarmers,duetoreduceduseofinsecticides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3Bt作物的昆虫抗药性管理CriticalcomponentsofIRMplan

IRM计划的重要组成成分Pestbiology害虫生物学Dose剂量Cross-resistance抗性转移Refuge避难所Modeling建立模型Resistancemonitoring抗性监测Remedialaction矫正措施Complianceassurance确保规范性Growereducation种植者教育4Bt作物的昆虫抗药性管理Pestbiology

害虫生物学Importantfactorsinclude:NumberofinsectgenerationsperyearHostrangeInsectmovementanddispersalpatternsMatingandovipositionalbehaviorPopulationdynamics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5Bt作物的昆虫抗药性管理Pestbiology:anexample

害虫生物学举例Europeancornborer(ECB),Ostrinianubilalis1-4generationsperyearPolyphagous(preferscorn)Movement:Larvae-canmovefromplant-to-plantwithinafieldAdults-mostlylocalmovement,butsomelongdistancemigratorymovementcanoccur欧洲玉米螟(ECB)每年繁殖1-4代杂食性(偏好玉米)移动幼虫可以在同一田地内不同植株上移动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Male雄性lateinstars晚期幼虫ECB6Bt作物的昆虫抗药性管理Dose剂量Dose=theamountoftoxinexpressedovertimebyatransgeniccrop,relativetothesusceptibilityofatargetpest;canbedeterminedthroughfieldefficacytrialsorlaboratorybioassays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.Highdose=atleast25xtheamountoftoxinneededtokillallsusceptibletargetinsects;preferredoverlowdoseeventsforrefuge-basedIRMstrategies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7Bt作物的昆虫抗药性管理Doseassumptions

剂量假设Threegenotypesforresistance/susceptibility(SS,rS,rr)Resistance(rr)isrecessiveandrareRefugesuppliesSS(homozygoussusceptible)genotypeRandommating:rrxSS→rSrSxSS→rSorSSSSandrSsusceptibletohighdose三种抗性/敏感性基因型(SS,rS,rr)抗性基因(rr)是隐性的,少见的安全基因型SS(纯合敏感)随机交配:rrxSS→rSrSxSS→rSorSSSS和rS对高剂量敏感LC500100低高8Bt作物的昆虫抗药性管理Doselevels:someexamples

关于剂量水平的一些例子Lepidopteran-activecorn(Cry1Ab&Cry1F):HighdoseEuropeancornborer(ECB),OstrinianubilalisSouthwesterncornborer(SWCB)DiatraeacrambidoidesNon-highdoseCornearworm(CEW),Helicoverpazea鳞翅目敏感玉米(Cry1Ab&Cry1F):高剂量欧洲玉米螟(ECB),Ostrinianubilalis西南玉米螟(SWCB)Diatraeacrambidoides非高剂量玉米棉铃虫(CEW),HelicoverpazeaWCRfemalemalelateinstarsECB9Bt作物的昆虫抗药性管理Doselevels:someexamples

关于剂量水平的一些例子Rootworm-activecorn(Cry3Bb1,Cry34/35,mCry3A)Non-highdoseWesterncornrootworm(WCR),DiabroticavirgiferavirgiferaNortherncornrootworm(NCR),D.barberiMexicancornrootworm(MCR),D.virgiferazeaSecondarypestsNon-highdoseforsomepests根虫敏感玉米(Cry3Bb1,Cry34/35,mCry3A)非高剂量西部玉米根虫(WCR),Diabroticavirgiferavirgifera北部玉米根虫(NCR),D.barberi墨西哥玉米根虫(MCR),D.virgiferazea次级害虫非高剂量WCRfemalemalelateinstarsECB10Bt作物的昆虫抗药性管理Cross-resistance

抗性转移WhenresistancetoasingleBttoxinconferspestresistancetoaclusterofrelatedtoxinsFactorsaffectingcross-resistanceinclude:Similarity/dissimilarityofcommercializedtoxinsUseofsingletoxinversusmultipletoxinsLevelofresistanceinaninsectpopulation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11Bt作物的昆虫抗药性管理Cross-resistance:anexample(抗性转移:举例说明)BindingsitediagramforEuropeancornborer(欧洲玉米螟结合位点简图)Cry1AbCry1FCry1Ac220KDaCadherin154KDaAPN145/167KDaAPNOtherEuropeancornborer(basedonHua,G.,Masson,L.,Jurat-Fuentes,J.L.,Schwab,G.,Adang,M.J.2001.BindinganalysesofBacillusthuringiensisCryd-endotoxinsusingbrushbordermembranevesiclesofOstrinianubilalis.Appl.Env.Microbiol.67:872-879)(其他)12Bt作物的昆虫抗药性管理Refuge避难所AnyhostplantthatdoesnotproduceBttoxinandhasnotbeentreatedwithconventionalBtformulations(maybetreatedwithnon-Btinsecticide)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杀虫剂处理过)Enablesmatingbetweenresistantandsusceptibleadults,resultinginproductionofsusceptibleoffspring抗性和敏感性成熟植株杂交可以产生敏感性的后代13Bt作物的昆虫抗药性管理Refugeoptions 避难所的选择Structuredrefuge=specifiedsize,locationinrelationtoBtfield,andcrop/plantcompositionCommunity-basedrefuge=neighboringgrowersestablishsharedstructuredrefugeUnstructuredornaturalrefuge=useofalternativehostplants/cropsinplaceofdefinedrefuge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14Bt作物的昆虫抗药性管理Refugeoptions 避难所的选择Seedbagmix=BtseedbagscontainBtseedandnon-Btseed(e.g.,80%Bt,20%non-Bt);seedmaybebaggedseparatelyormixedtogetherRegionallimit=national/regionalgovernmentenforcedlimitonBtseedsales(e.g.,80%indefinedregion)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混和,也可以直接混在一起.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)15Bt作物的昆虫抗药性管理SeedmixBlockIn-fieldstrips田地内的条带模式Internalblock(s)内部种植模式Border(block)周边种植模式Structuredrefugeoptions

结构避难所的选择Externalblock外部种植模式种子混和16Bt作物的昆虫抗药性管理Otherrefugeoptions

其他避难所选择Communityrefuge社区避难所模式80%Bt

seedcorn玉米种子20%non-Bt

seedcorn玉米种子Naturalrefuge天然避难所BtcottonBt棉花w/TBWSoybean大豆Tobacco烟草Tobaccobudworm,烟草蚜虫Heliothisvirescens

17Bt作物的昆虫抗药性管理Btcornrefugespecifications:anexample

Bt玉米避难所规范示例20%refugerequiredincornbelt;50%refugerequiredincorn/cottonregionStructuredrefugeisrequired.Refugesmaybeplantedinoneofthefollowingdesigns:In-fieldstrips(4-6rows)Blocks(internalorexternal)Refugerequirementsarethesameforlepidopteranandcoleopteranactiveproducts在Bt玉米田中20%为避难所,在玉米/棉花田中则为50%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18Bt作物的昆虫抗药性管理Modeling模拟Usefultoolforpredictingthelikelihoodofresistance,forevaluatingthedurabilityofIRMstrategies,andforhelpingtofocusdataneeds.Modelcomponentsinclude:Biologicalinformation(pestbiology,populationdynamics)Genetics(R-alleledominance/frequency,crossresistance)Operationalaspects(dose,single/stackedtoxin(s),refuge)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)19Bt作物的昆虫抗药性管理Resistancemonitoring

抗性监测CanhelptoprolongtheefficacyofaninsectresistantcropDesignedtodetectresistance2-3yearsbeforefieldfailureTargetpestsamplingconsistsof:Growerreportsofunexpectedpestdamageininsect-protectedcropfieldsRandompopulationsampling:SamplingbasedonpestprevalenceinregionSamplingtarget:numberofinsectsneededtodetermineresistanceatp<0.01

可以延长抗虫作物的功效可以在失效前监测抗性2-3年目标害虫取样包括: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:害虫流行区域取样取样目标:用来确定抗性所需的害虫数量(p<0.01)20Bt作物的昆虫抗药性管理Resistancemonitoring(cont.)

抗性监测(续)Bioassaysareusedtodetectpotentialresistanceinsampledpopulations.Assaysinclude:Pestsusceptibility(LC50)DiscriminatingDose(LC99)F2screenConfirmationstudiesareusedtoverifyresistance.Questionsinclude:Istherefieldfailure?Istheinsectresistancetraitexpressed?Isinsectresistancetraitinherited?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?21Bt作物的昆虫抗药性管理Resistancemonitoring:positivehitsforBtcornintheUS?抗性监测:美国Bt玉米正采样数In2001,mortalityforoneEuropeancornborer(ECB)population(Kandiyohi,MN)was<99%inCry1AbdiscriminatingdoseassayFollow-uptestswithBtplantmaterialrevealedthatpopulationwasnotfieldresistantNofieldresistanceconfirmedforanymonitoredBtcornpest2001年在Cry1Ab不同剂量分析中,欧洲玉米螟种群的死亡率小于99%Bt作物的后续测试表明种群并没有田间抗药性被监测的Bt玉米害虫没有被证实产生田间抗药性22Bt作物的昆虫抗药性管理Remedialactionplan

矫正措施 Ifresistanceisconfirmedthroughresistancemonitoring,aremedialactionplanisimplementedtocontainorslowthespreadofresistantpestpopulations

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23Bt作物的昆虫抗药性管理Remedialactionplan:anexample

矫正措施举例EPA’splanincludes:MandatoryreportingofsuspectedresistanceUseofalternatecontrolmeasuresinaffectedareasIncreasedresistancemonitoringSuspensionofBtcropsalesinaffectedareasInvestigationofcauseofresistance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24Bt作物的昆虫抗药性管理Complianceassurance

确保规范性

CompliancemeasuresimplementedtoensurethatgrowerscomplywithapprovedIRMprogram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.25Bt作物的昆虫抗药性管理Complianceassurance:anexample

确保规范性举例EPArequiresregistrantstoimplementthefollowingmeasures:ContractsaffirminggroweragreementtocomplywithapprovedIRMstrategy3rdpartygrowersurveysofIRMimplementationOn-farmfieldvisitstoverifyIRMimplementationTipsandcomplaintsonnon-compliersSuspensionofseedaccessfornon-compliers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供应26Bt作物的昆虫抗药性管理Growereducation

种植者教育

EducationabouttheneedforIRM,howtoimplementrequirements,andgrowerresponsibilityincomplyingwithIRMrequirements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27Bt作物的昆虫抗药性管理SummaryofEPA’sIRMrequirementsforlepidopteran-activeBtcorn

美国环保局对鳞翅目昆虫敏感的Bt玉米IRM要求概述20%refugeincornbelt;50%refugeincottonbeltStructuredrefugerequired.Refugesplantedinoneofthefollowingdesigns:in-fieldstrips(4-6rows)blocks(internalorexternal)Industry-widecollaborationoncompliancesurveys在玉米种植带中20%为避难所;在棉花种植带中为50%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:田间条带(4-6行)田块(内部或外部)广泛合作开展规范性调查28Bt作物的昆虫抗药性管理SummaryofEPA’sIRMrequirementsforlepidopteran-activeBtcorn(cont.)

对鳞翅目昆虫敏感的Bt玉米IRM要求概述(续)Industry-wideuniformityof:GroweragreementsGrowertrainingImplementationoftipsandcomplaints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29Bt作物的昆虫抗药性管理SummaryofEPA’sIRMrequirementsforlepidopteran-activeBtcorn(cont.)对鳞翅目昆虫敏感的Bt玉米IRM要求概述(续)Annualreportingrequirements:－Complianceassurance(e.g.,surveys,growercontracts)－Changestogrowereducation－Resistancemonitoringdata－Salesdata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30Bt作物的昆虫抗药性管理DatasourcesforEPA’sIRMprogram

美国环保局IRM项目的数据来源PublishedscientificliteratureIndustrysubmissionsExperts(academia,government,industry)Meetings(advisorypanels,workshops,ESA,NC205,NC46)Fieldvisits已出版的科学文献工业企业的报告专家(学术界,政府,工业界)会议(顾问团,研讨会,ESA,NC205,NC46)田间观察31Bt作物的昆虫抗药性管理KeystosuccessatEPA

美国环保局(EPA)取得成功的关键EPAisresponsivetonewscientificinformationEPAseeksscientificinputfromstateandfederalagencies,academicexperts,andpublicinterestgroupsEPA对最