Bt作物的昆虫抗药性管理(1)

1InsectResistanceManagementforBtCropsBt作物的昆虫抗药性管理TessaMilofsky,M.S.andSharleneMatten,Ph.D.泰莎.米洛夫斯基硕士沙利恩.马顿博士U.S.EnvironmentalProtectionAgencyOfficeofPesticidePrograms美国环保局杀虫剂项目办公室2IRM: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.3IRM: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:–Btreplaceshigherriskpesticides–Bt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4CriticalcomponentsofIRMplanIRM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5Pestbiology害虫生物学Importantfactorsinclude:–Numberofinsectgenerationsperyear–Hostrange–Insectmovementanddispersalpatterns–Matingandovipositionalbehavior–Populationdynamics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6Pestbiology:anexample害虫生物学举例Europeancornborer(ECB),Ostrinianubilalis–1-4generationsperyear–Polyphagous(preferscorn)–Movement:Larvae-canmovefromplant-to-plantwithinafieldAdults-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ECB7Dose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8Doseassumptions剂量假设Threegenotypesforresistance/susceptibility(SS,rS,rr)Resistance(rr)isrecessiveandrareRefugesuppliesSS(homozygoussusceptible)genotypeRandommating:–rrxSS→rS–rSxSS→rSorSSSSandrSsusceptibletohighdose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→rS–rSxSS→rSorSSSS和rS对高剂量敏感DoseMortalitySSrSrrLC500100低高9Doselevels:someexamples关于剂量水平的一些例子Lepidopteran-activecorn(Cry1Ab&Cry1F):–HighdoseEuropeancornborer(ECB),OstrinianubilalisSouthwesterncornborer(SWCB)Diatraeacrambidoides–Non-highdoseCornearworm(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),HelicoverpazeaWCRfemalemalelateinstarsECB10Doselevels:someexamples关于剂量水平的一些例子Rootworm-activecorn(Cry3Bb1,Cry34/35,mCry3A)–Non-highdoseWesterncornrootworm(WCR),DiabroticavirgiferavirgiferaNortherncornrootworm(NCR),D.barberiMexicancornrootworm(MCR),D.virgiferazeaSecondarypests–Non-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WCRfemalemalelateinstarsECB11Cross-resistance抗性转移WhenresistancetoasingleBttoxinconferspestresistancetoaclusterofrelatedtoxinsFactorsaffectingcross-resistanceinclude:–Similarity/dissimilarityofcommercializedtoxins–Useofsingletoxinversusmultipletoxins–Levelofresistanceinaninsectpopulation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12Cross-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)13Refuge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14Refugeoptions避难所的选择Structuredrefuge=specifiedsize,locationinrelationtoBtfield,andcrop/plantcompositionCommunity-basedrefuge=neighboringgrowersestablishsharedstructuredrefugeUnstructuredornaturalrefuge=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15Refugeoptions避难所的选择Seedbagmix=BtseedbagscontainBtseedandnon-Btseed(e.g.,80%Bt,20%non-Bt);seedmaybebaggedseparatelyormixedtogetherRegionallimit=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)16SeedmixBlockIn-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17Otherrefugeoptions其他避难所选择*********************