不同种昆虫病原线虫对同一寄主个体的竞争及对线虫繁殖的影响

采用注射侵染和自然侵染法，测试了长尾斯氏线虫X-7品系、小卷蛾斯氏线虫All品系和嗜菌异小杆线虫H06品系对同一寄主大蜡螟幼虫的相互作用，及其对线虫繁殖的影响。结果表明，无论是注射侵染还是自然侵染法，对大蜡螟幼虫个体的致死竞争能力最强的是长尾斯氏线虫，其次是小卷蛾斯氏线虫，嗜菌异小杆线虫的致死能力最弱。在同一大蜡螟幼虫体内时。异小杆线虫的繁殖受斯氏线虫的不利影响较大，而两种斯氏线虫的繁殖受异小杆线虫的不利影响较小。两种斯氏线虫对各自的繁殖影响不大。     

昆虫病原线虫对腰果云翅斑螟的室内致病力

研究了小卷蛾斯氏线虫Steinernema carpocapsae All品系、Biosys品系,格氏斯氏线虫S.glaseri NC52品系,长尾斯氏线虫S.longicaudum X-7品系,嗜菌异小杆线虫Heterorhabditis bacteriophora H06品系和印度异小杆线虫H.indica LN2品系6个昆虫病原线虫品系在室内对腰果云翅斑螟Nephopteryxsp.幼虫的致病力。结果表明,除了嗜菌异小杆线虫,其他参试线虫对腰果云翅斑螟3龄幼虫均具有较高的致病力,致死率80.0%~95.0%,各处理差异不显著。嗜菌异小杆线虫对腰果云翅斑螟幼虫控制效果最差,显著低于其他参试线虫。选择小卷蛾斯氏线虫All品系进一步研究其对腰果云翅斑螟的致病效果,结果发现,其对腰果云翅斑螟3龄幼虫处理24h后的LC50为22.94IJs/头。处理24h,小卷蛾斯氏线虫All品系对1~3龄幼虫的致死率(72.5%~84.7%)显著高于4~5龄幼虫(15.0%~30.0%);处理120h,对蛹的致死率仅为20.0%。研究表明,小卷蛾斯氏线虫All品系对腰果云翅斑螟低龄幼虫在室内具有一定控制潜力。     

利用昆虫病原线虫与化学农药混用防治褐纹甘蔗象

褐纹甘蔗象是棕榈科植物和甘蔗的新入侵危险害虫。本研究利用昆虫病原线虫小卷蛾斯氏线虫All品系与毒死蜱、吡虫啉混用防治褐纹甘蔗象。将4000条／ml感染期线虫与48％毒死蜱EC（1000mg／L）、70％吡虫啉（500mg／L）混合施用于国王椰子，7d后对幼虫的防效为96％，明显优于单剂毒死蜱（68．96％）、单剂吡虫啉（0）和小卷蛾斯氏线虫（68．42％～76．52％）的防效；混剂处理7d对成虫的防效为88．89％，亦明显优于单剂毒死蜱（72％）、单剂吡虫啉（2．50％）和小卷蛾斯氏线虫（27．78％～52．63％）。     

利用昆虫病原线虫防治蔗扁蛾的研究

通过应用昆虫病原线虫斯氏线虫属小卷蛾线虫的Agriotos、Beijing和CB163个品系,格氏线虫的NC34品系,以及异小杆线虫属嗜菌异小杆线虫的E67品系对蔗扁蛾进行室内及田间防治试验。结果表明:小卷蛾线虫Agriotos和Beijing2个品系对蔗扁蛾幼虫具有明显的防治效果。应用注射法将含侵染期线虫1000～2000条/ml线虫悬浮液约200ml注入巴西木受害部位表皮下,5d后防治效果达7363%。     

古巴斯氏线虫生物学特性的研究

对采自热带地区的古巴斯氏线虫的生物学特性进行了研究,结果表明： 该线虫侵染大蜡螟幼虫的温度范围为１５～３５℃;在２５℃下,线虫在大蜡螟幼虫体内完成一个侵染周期需２００～２１２小时;对大蜡螟幼虫的侵入率为４２．８％ 。在常温（２０～３３℃）下贮存６个月后其存活率为９３．５％ ;侵入率为３１．３％ 。古巴斯氏线虫的耐高温能力和运动能力均优于小卷蛾线虫Ａ２４品系,但耐干燥能力较差。古巴斯氏线虫的耐高温及常温下耐贮存的特性显示了其在防治害虫上的应用潜力     

小卷蛾斯氏线虫对辣椒烟粉虱的控制作用

本文研究了小卷蛾斯氏线虫Steinernema carpocapsae对烟粉虱Bemisia tabaci的侵染能力以及对田间辣椒烟粉虱的控制作用。结果表明，室温（28±2）℃，空气湿度（60±5）%，辣椒叶背面湿润的条件下，线虫约在4 h侵入烟粉虱若虫体内，2～3 d内致其死亡。不同浓度线虫对烟粉虱若虫的控制效果不同，小卷蛾斯氏线虫All品系22、16和13 IJs/mL对烟粉虱高龄（3龄和4龄）若虫的致死率分别为42.79%，34.74%，29.31%，对低龄（1龄和2龄）若虫的致死率分别为44.58%、41.66%、39.61%。助剂5% d-柠檬烯可溶液剂与线虫联合使用具有促进效果，线虫稀释22 IJs/mL，配合1000倍液5% d-柠檬烯可溶液剂时效果最佳，高龄若虫和低龄若虫的致死率分别达到60.61%和61.55%。田间辣椒叶片表面施水量对烟粉虱的防治效果存在明显的影响，在田间施水1.5、1、0.5 L/m²的条件下，高龄若虫校正死亡率分别为66.49%、66.50%、47.78%，低龄若虫校正防治效果分别为69.30%、58.52%、51.83%。综上，喷施小卷蛾斯氏线虫对烟粉虱有一定的控制效果，配合助剂5% d-柠檬烯可溶液剂有促进作用，保持辣椒叶片表面湿润可以提高对烟粉虱的防治效果。     

5种杀虫剂对小卷蛾斯氏线虫存活和侵染的影响及其交互作用

共测定了茚虫威、溴氰虫酰胺、呋虫胺、吡蚜酮、吡虫啉5种蔬菜常用杀虫剂在不同浓度下(2RC、RC、1/2RC、1/5RC、1/10RC)对昆虫病原线虫小卷蛾斯氏线虫(Steinernema carpocapsae) All品系存活和侵染的影响,以及药剂与线虫的交互作用。结果表明,吡虫啉对线虫的影响最大,在5种处理浓度下,线虫死亡率达10%～14%;其他4种药剂处理后,线虫死亡率在4%～7%之间。5种药剂对线虫侵染力均无不利影响。其中,吡虫啉在推荐浓度RC处理下增强了线虫侵染力。5种化学药剂与线虫均无拮抗作用。溴氰虫酰胺(2RC、RC、1/2RC)、吡虫啉(2RC、RC、1/5RC、1/10RC)、吡蚜酮(RC、1/2RC、1/5RC、1/10RC)与线虫混用后48 h对黄粉虫有增效作用。     

三种斯氏线虫与其共生细菌之间的专化性

在自然条件下,芜菁夜蛾斯氏线虫、长尾斯氏线虫和拟双角斯氏线虫体内携带的共生细菌分别为伯氏致病杆菌、Xenorhabdus ehlersii和X.budapestensis。在一种线虫的生长培养基上分别接种3种致病杆菌,测试对线虫的恢复发育、性比、后代产量及形态大小的影响。结果表明,芜菁夜蛾斯氏线虫与致病杆菌的专化性低于长尾斯氏线虫和拟双角斯氏线虫,在3种致病杆菌上均可发育,但在伯氏致病杆菌上的发育率显著高于X.ehlersii和X.budapestensis。长尾斯氏线虫和拟双角斯氏线虫侵染期幼虫仅在其各自共生细菌X.ehlersii和X.budapestensis上发育。芜菁夜蛾斯氏线虫侵染期幼虫在伯氏致病杆菌上发育后的雌雄比为1.77,而在X.ehlersii和X.budapestensis上仅为0.77和0.74;在伯氏致病杆菌上的产量高于X.ehlersii和X.budapestensis;在伯氏致病杆菌和X.ehlersii上产生的侵染期幼虫长度显著大于X.budapesten-sis。对3种致病杆菌上培养产生的芜菁夜蛾斯氏线虫侵染期幼虫体内携带的细菌进行分离和16S rDNA序列分析,表明芜菁夜蛾斯氏线虫侵染期幼虫除可携带其共生细菌伯氏致病杆菌外,还可携带X.budapestensis,但不能携带X.ehlersii。     

小卷蛾斯氏线虫All品系对小菜蛾感染力测定

本文测定了小卷蛾斯氏线虫（S. carpocapsae）All品系对小菜蛾的感染力。结果表明：加入辅助剂的线虫液喷施于蔬菜叶面后,线虫的侵染率显著提高,证明黄原胶是一种很好的抗干燥物质;同时表明线虫的最适宜喷洒浓度为感染期幼虫3 000条/mL;线虫对小菜蛾3龄幼虫的侵染率最高;线虫的侵染率不会随着蔬菜上小菜蛾密度的增加而下降。     

离体时间及短期贮存对三种斯氏线虫侵入率及运动能力的影响

本文研究了小卷蛾线虫、拟双角斯氏线虫、古巴斯氏线虫用大蜡螟幼虫繁殖时其脱离寄主虫体时间和离体后短期贮存对线虫侵入率及运动能力的影响。结果表明：线虫离体时间对其侵入率有一定影响,第１天离体的线虫其侵入率均大于第７天离体的线虫,这在古巴斯氏线虫中异常显著。在３０天贮存期内,３种线虫随着贮存期的延长,其侵入率逐渐提高,小卷蛾线虫和拟双角斯氏线虫一般贮存７天,古巴斯氏线虫贮存１５天,其侵入率即达到高峰,以后基本趋于稳定;经短期贮存后,除古巴斯氏线虫的运动能力无显著提高外,其它两种线虫贮存１０天后其运动能力均高于刚离体的线虫。     

三种化学杀虫剂对病原线虫侵染暗黑鳃金龟能力的影响

昆虫病原线虫作为生物杀虫剂已被广泛应用。为了提高其对蛴螬的防治效果,筛选与昆虫病原线虫适宜混用的化学杀虫剂是一项重要的应用研究。本研究测试了70%吡虫啉水分散粒剂、40%毒死蜱乳油和2.5%高效氯氰菊酯乳油对病原线虫Heterorhabditis bacteriophora Cangzhou strain、Steinernema longicaudumX-7和Heterorhabditis indica LN2存活以及侵染率的影响;筛选出杀虫剂与病原线虫混合对暗黑鳃金龟Holotrichia parallela 2龄幼虫致死效果的最佳配比。结果显示：3种杀虫剂对3种线虫的存活均无亚致死作用;吡虫啉对3种线虫的致死率无明显影响,其中LN2在1/50 RC（含量为9.33μg mL 1）和1/100 RC（4.67μg mL 1）低浓度处理的死亡率显著低于对照;推荐浓度的高效氯氰菊酯（16.67μg mL 1）对3种线虫的致死率均显著高于对照;不同浓度的毒死蜱对3种线虫的致死率存在显著差异。70%吡虫啉1/10推荐浓度（有效成分为46.67μg mL 1）与线虫Hb混用暗黑鳃金龟2龄幼虫死亡率提高了87.51%,与X-7和LN2混用后,致死率分别提高了39.99%和47.37%。其中1/10推荐浓度吡虫啉与线虫Hb混用对暗黑鳃金龟2龄幼虫表现出增效作用,其它浓度的吡虫啉和另外两种药剂与3种线虫混用的各处理均表现为相加作用。     

Association between entomopathogenic nematodes and non-synthetic insecticides for improved control of Nasutitermes spp. (Isoptera: Termitidae) in sugarcane plantations

The aim of this study was to evaluate the in vitro efficacy of the combination of entomopathogenic nematodes and non-synthetic insecticides in the control of Nasutitermes spp. (Isoptera: Termitidae). Bioassays were performed upon insect collection from areas with the high incidence of this pest. The experimental arena for insecticide assays consisted of 80-mL plastic containers with a screened cover. We tested six insecticides and the nematode species Heterorhabditidis bacteriophora RS58, Steinernema glaseri RS38, and Heterorhabditis sp. isolates AL39, AL40, AL41, AL42, AL43, AL44, AL46, and AL47, all of which were grown in last-instar larvae of Galleria mellonella L. (Lepidoptera: Pyralidae). The insecticides Codipirol®, Pure Neem Oil®, and Pyroligneous Acid Extract® caused high mortality in adults of Nasutitermes. The nematode Heterorhabditis sp. AL40 presented a median lethal concentration of 7976 infectious juveniles per adult of Nasutitermes sp. In addition, the mixture of these three non-synthetic products at a concentration of 3% caused complete mortality in Heterorhabditis sp. AL40 and S. glaseri RS38. Future trials should be encouraged in order to evaluate the field efficiency of non-synthetic insecticides mixed or not with entomopathogenic nematodes.     

昆虫病原线虫防治甜菜地蛴螬的初步研究

东北黑鳃金龟幼虫是甜菜的主要害虫，利用昆虫病原线虫ＳｔｅｉｎｅｒｎｅｍａｇｌａｓｅｒｉＮＣ３２品系在甜菜苗期防治小区试验表明，每平方米施用线虫１００万头，幼虫死亡率可达８５．３％。大田防治结果，每６６７ｍ^２施用４亿头线虫，幼苗被害率可控制在１５．１％以下，效果明显高于某些化学农药。线虫防治田与对照田相比，能显著的控制蛴螬的种群数量，使甜菜每６６７ｍ^２增产３５１ｋｇ，表明利用线虫防治甜菜地蛴螬的可行性，为地下害虫无公害防治开辟了新途径。     

北京地区昆虫病原线虫的自然发生情况初步调查

用大蜡螟诱集法,对在北京地区采集的175个土样进行了线虫分离,得到斯氏属线虫5个,异小杆属线虫6个,小杆线虫2个。土样有线虫率为13.1％。土样有线虫率与植被、土壤质地有关。从4种植被下采集土样的有线虫率分别是:果园28.2％、菜地10.5％、大田作物7.7％、未耕地0。4种土壤质地中土样有线虫率为:松沙土20.8％、砂壤土15.1％、中壤土12.2％、轻壤土5.4％。本土线虫对桃小食心虫、韭菜蛆、小木蠹蛾、二化螟的侵染力均高于引进的线虫。     

一种对桃小食心虫高毒力的斯氏线虫Steinernema sp.(CB-2Y)

本研究在室内用“沙埋法”比较了两种斯氏属昆虫病原线虫Steinernema sp.(CB-2Y)和S.feltiae Agriotos对桃小食心虫的侵染力,结果表明CB-2Y线虫对桃小食心虫幼虫和冬茧的侵染力都高于Agriotos线虫。接线虫笫7天桃小食心虫LD50,CB-2Y组为49条线虫,而Agriotos组为158条;冬茧的LD50分别为1330条和24046条。在桃小冬茧开始活动期(6月15日)分别施用两种线虫,一个月后检查桃小食心虫成虫羽化率,CB-2Y线虫的控制效果明显优于Agriotos,在1024条线虫/桃小食心虫冬茧时(75条/cm~2),越冬代桃小食心虫的羽化率分别为8.2％和29.2％。     

Effect of rapid and gradual increase of osmotic stress on survival of entomopathogenic nematodes

The effect of rapid and gradual exposure of entomopathogenic nematodes to osmotic stresses on the induction of a dormant state was determined with the nematodeSteinernema feltiae IS-6 infective juveniles (IJs). Rapid exposure of nematodes to glycerol at concentrations of 24% and 28% (w/w) caused the nematodes to enter a dormant state which was characterized by shrinking and impeded motility of all nematodes within 8 h. However, pre-exposure to gradually increasing glycerol concentrations of 5%, 10% and 18% at 4-h intervals resulted in dormancy after 4 h exposure to 24% glycerol. The total time of exposure to glycerol solution was 16 h in gradual osmotic stress. For nematodes exposed to 24% glycerol solution either rapidly or gradually, recovery occurred after 40 min in distilled water. Infectivity of osmotically stressedS. feltiae IJs was evaluated by two criteria, insect mortality and invasion rate. The assays indicated that infectivity of nematodes desiccated by rapid and gradual osmotic stresses was similar to that of fresh nematodes. Rapid exposure ofS. carpocapsae ‘All’,S. riobravis ‘Texas’,S. glaseri ‘NI’ andHeterorhabditis bacteriophora HP88 IJs to the 24% glycerol solution resulted in dormancy within 8 h. These treatments caused mortality of 48.4% and 11.7% amongS. glaseri Nl andH. bacteriophora HP88 IJs, respectively. Similar effects were observed when these nematode species were exposed to increasing osmotic stress of 5%, 10% and 18% at 6-h intervals. Under these same conditions, mortality ofH. bacteriophora HP88 andS. glaseri Nl IJs was 27.5% and 61.8%, respectively. http://www.phytoparasitica.org posting Sept. 29, 2004.     

Cotton whitefly (Bemisia tabaci) resistance to organophosphate and pyrethroid insecticides in Pakistan

Resistance to three organophosphate and four pyrethroid insecticides was monitored from 1992 to 2000 in field populations of adult whiteflies, Bemisia tabaci, from Pakistan using a leaf-dip method. There was generally a very high resistance to dimethoate and deltamethrin, and a moderate resistance to monocrotophos during 1992 to 1996. From 1997 to 2000, resistance to these insecticides dropped to low levels because of less reliance on them for whitefly control, and introduction of new chemistries with novel modes of action that had no cross-resistance to conventional insecticides. Concurrently, whitefly resistance to acephate, fenpropathrin, lambda-cyhalothrin and bifenthrin mostly remained low. An insecticide resistance management strategy is recommended that particularly emphasizes the rotation of still-effective insecticides from different chemical classes along with the use of novel chemicals and other tactics of integrated pest management.     

斯氏线虫CB—2Y品系对李实蜂的侵染试验

李实蜂是李子果实的重要害虫。本文探讨了斯氏线虫 CB-2Y 品系对李实蜂幼虫、茧的室内及田间侵染力。结果表明:1.李实蜂幼虫对该线虫很敏感,96小时死亡率93.3%～100%,茧不敏感,死亡率0～6.2%。2.该线虫对李实蜂幼虫侵染力很强,幼虫死亡率随作用时间及剂量浓度增加而增高。3.该线虫侵染李实蜂的田间效果7天后死亡率为70%左右,18天后死亡率达75%以上。     

斯氏线虫对进境原木上长林小蠹的防治试验

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