昆虫病原线虫对腰果细蛾的致病力测定

室内测定了Steinernema carpocapsae All、S.carpocapsae Biosys、S.glaseri NC52、S.longicaudum X-7、Heterorhabditis bacteriophora H06和H.indica LN2共6个昆虫病原线虫品系对腰果细蛾Acrocercops syngramma Meyrick幼虫的致病力。结果表明,线虫S.carpocapsae All、Biosys品系与线虫S.glaseri NC52对腰果细蛾幼虫的致死效果显著高于其它线虫,但供试的6个线虫品系均未能在腰果细蛾幼虫体内繁殖下一代,说明供试线虫在腰果细蛾幼虫体内难以繁殖。选择小卷蛾斯氏线虫S.carpocapsae All进一步研究其对腰果细蛾的致病力,结果发现,All线虫对腰果细蛾3龄幼虫处理24 h后的致死中浓度LC50为19.88 IJs/虫。腰果细蛾各龄幼虫和蛹对小卷蛾斯氏线虫S.carpocapsae All均表现出高度的敏感性,但不同幼虫龄期和处理时间敏感程度不同。小卷蛾斯氏线虫S.carpocapsae All对不同龄期腰果细蛾幼虫和蛹均表现出较强的致病力。     

昆虫病原线虫与其共生细菌共生关系的研究进展

昆虫病原斯氏和异小杆线虫与共生细菌的共生关系是这类线虫作为害虫生物防治因子的基础。从线虫共生细菌的信息、营养、抗菌和病原作用,以及线虫对共生细菌的保护和媒介作用综述昆虫病原线虫与其共生细菌的共生关系;描述这一共生关系的影响因子;同时,讨论了未来的研究方向和应用前景。     

一种昆虫病原斯氏线虫杂交的新方法

将大蜡螟幼虫或蛹剪成2—3段,挑入配对种的感染期幼虫各一条,24—26℃保湿条件下,一周左右可获杂交结果。较常规的注射法和昆虫血液悬滴法操作方便,培养条件也要求不严,试用效果良好。做过的1594对线虫的交配试验,成功率在95％以上。     

昆虫病原线虫防治草地贪夜蛾的研究进展

草地贪夜蛾Spodoptera frugiperda是一种重要的世界性害虫,目前已扩散至我国十余个省、市(区)。由于草地贪夜蛾已报道对多种常用农药及Bt等制剂产生抗性,因此寻求新的生防制剂具有重要的意义。昆虫病原线虫具有防治草地贪夜蛾的应用潜力。本文从昆虫病原线虫品系、保护剂、增效药剂、施用技术以及综合防控等方面综述了昆虫病原线虫防治草地贪夜蛾的研究进展,并对进一步开展应用昆虫病原线虫防治草地贪夜蛾的研究进行了展望。     

昆虫病原线虫斯氏线虫和异小杆线虫对长角血蜱雌蜱的致病力

用昆虫病原线虫小卷蛾斯氏线虫（Sc BJ）、夜蛾斯氏线虫（Sf Otio）、拟双角斯氏线虫（Sc D43）、格氏斯氏线虫（Sg NC32）和嗜菌异小杆线虫（Hb E-6-7）对长角血蜱雌蜱进行感染试验,所用线虫剂量为4 000 Ijs/dish。结果表明,5种线虫均对长角血蜱雌蜱有致死效应。Hb E-6-7和Sc BJ两种线虫对雌蜱各发育期致病力最强,导致雌蜱的累积死亡率和半致死时间分别为饥饿雌蜱82.5%,9.0天和75.0%,8.8天;吸血雌蜱90.0%,8.0天和82.5%,8.0天;饱血雌蜱93.3%,7.3天和86.7%,7.3天。Sc D43对饱血雌蜱有较高的致死效应,为80.0%,但半致死时间较长,为11.7天。Sf Otio和Sg NC32对长角血蜱雌蜱的致死效应较低。饱血雌蜱较饥饿雌蜱和吸血雌蜱更易被线虫感染。     

昆虫病原线虫(斯氏属与异小杆属)应用概况

<正> 在自然界,线虫与昆虫的联系是普遍的。据目前所知,至少有27个科的线虫与16个目近3000种昆虫有联系(Nickole 1984,Poinar 1983),其分布是由寄主昆虫的栖境所决定的。这些线虫对害虫的种群起着自然调节的作用。线虫与昆虫联系的方式各异,使人最感兴趣的是那些能作为害虫生物防治的病原线虫。自从Oldhan(1933)首次提出利用线虫防治害虫以来,应用病原线虫进行害虫生物防治的工作已     

昆虫病原线虫共生细菌共生性的分子生物学研究进展

嗜线虫致病杆菌属Xenorhabdus和发光杆菌属Photorhabdus细菌隶属肠杆菌科Enterobacteriaceae,对多种害虫致病能力强,分别与斯氏属Steinernema和异小杆属Heterorhabditis昆虫病原线虫互惠共生。该两属共生细菌既存在对昆虫寄主的病原性,又存在与线虫寄主的共生性。共生细菌与其线虫寄主的共生性主要表现以下4方面：（1）细菌产生食物信号诱导滞育不取食的感染期线虫恢复;（2）细菌为线虫生长与繁殖提供营养;（3）细菌能于感染期线虫的肠道定殖与生长;（4）细菌产生杀线虫毒素杀死非共生线虫。本文综述了共生菌以上4方面的共生性及其相关的分子机制。     

ITS-RFLP分析进行昆虫病原线虫斯氏属和异小杆属的分类鉴定

本研究通过PCR扩增和六种限制性内切酶（AluⅠ、HinfⅠ、MboⅠ、RsaⅠ、HaeⅢ和PvuⅡ）酶切,对国内害虫防治上常用的几种昆虫病原线虫,包括斯氏属S.carpocapsae、S.feltiae和S.glaseri以及异小杆属H.bacteriophora、H.zealandica、H.indicus和H.megulis等8个品系rDNA-ITS进行分析,建立起可以区分各线虫种的标准RFLP图谱.该方法快速简便、稳定可靠,需要的样品量少,可以用于新鲜的、或冻存的样品,甚至分析单条的线虫.不仅可进行昆虫病原线虫的快速分类鉴定,而且进一步可以应用于线虫田间释放的辅助监测,实际田间感染率的测定和线虫毒力的比较.     

Mechanical production of pellets for the application of entomopathogenic nematodes: factors that determine survival time of Steinernema glaseri

Applications of infective juveniles (IJ) of entomopathogenic nematodes (EPN) formulated in pellets are still limited. This is principally due to limited advances in the technology of formulation. We aimed to develop a new method of mechanical formulation through material flow and to analyse its effect on the survival time of encapsulated EPN by varying the granular materials, the components of the aqueous suspension, the age of the nematodes and by applying a surface coating (C) to the pellet. Three-day-old and two-month-old Steinernema glaseri IJ were encapsulated with different proportions of diatomaceous earth (DE) and attapulgite clay (AC). The aqueous suspension containing the nematodes was prepared with double distilled water (DDW), varying proportions of Opuntia ficus-indica mucilage (OM) or gelatin (GL), and a sunflower oil surface treatment. The pellets were stored at an average room temperature of 23 ± 6°C. The best results were obtained with the following proportions: 100DE:0AC and 50DE:50AC, using the OM suspension, three-day-old nematodes and a surface C, which resulted in an average of 14 days survival time. These results confirmed that the nematodes do not die during mechanical encapsulation and that the age of the IJ as well as the loss of moisture during storage at room temperature were the factors that decreased the survival of encapsulated EPN. It was concluded that it is necessary to use neonate IJ and to reduce the moisture transfer rate in the granular structure in order to delay the desiccation of the encapsulated nematodes.     

Pathogenicity of five species of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) to the ixodid tick Dermacentor silvarum Olenev (Acari: Ixodidae)

We determined the mortality of adult tick Dermacentor silvarum Olenev after it was exposed to five entomopathogenic nematode species: Steinernema carpocapsae BJ (Sc BJ), S. glaseri NC32 (Sg NC32), S. ceratophorum D43 (Sc D43), S. feltiae Otio (Sf Otio) and Heterorhabditis bacteriophora E-6-7 (Hb E-6-7). All five species had lethal effects on adult ticks, and caused significant decreases in the amount of eggs laid by engorged female ticks (P < 0.05). Among them, Hb E-6-7 and Sc BJ were the most pathogenic to female adult ticks, with mortalities ranging from 70 to 90% (P < 0.05). Engorged females were more susceptible than unfed and partially fed females. The cumulative mortalities of engorged females exposed to Hb E-6-7 and Sc BJ for 14 days were 90%, with LT₅₀ at 6.3 and 7.0 days, respectively. Dose-dependent effect was observed in the oviposition of the ticks after they were exposed to nematodes at concentrations of 1000–5000 IJs/dish. When the concentration was higher than 5000 IJs/dish, dose dependent effects disappeared (P > 0.05). All five nematode species were lethal to unfed male ticks, and there was significant difference in mortality when compared to the control group (P < 0.05); however, the pathogenicity varied among them.     

昆虫病原线虫Steinernema longicaudum X-7增效药剂的筛选

测试了19种昆虫生长调节剂、植物源或病毒类药剂对昆虫病原线虫Steinernema longicaudumX-7的存活和侵染率的影响。筛选9种对线虫存活和侵染率均无影响的药剂,测定其与线虫混用对黄粉虫Tenebrio molitorL.9~11龄幼虫的交互作用。结果显示,各种参试药剂和线虫组合均表现为相加作用。为了进一步确定参试药剂与线虫混用对目标昆虫卵圆齿爪鳃金龟Holotrichia ovataChang 3龄幼虫的交互作用,本研究选择氟虫脲、除虫脲、灭幼脲、苦参碱、氟啶脲和虫酰肼在低浓度下与线虫混用,除虫脲与线虫混用对测定昆虫处理7 d后表现为增效作用,其它药剂与线虫则表现为相加作用;各种参试药剂与线虫组合处理14 d后均表现为相加作用。     

Field evaluation of entomopathogenic nematodes for the biological control of the annual bluegrass weevil,Listronotus maculicollis (Coleoptera: Curculionidae), in golf course turfgrass

The ability of entomopathogenic nematodes to suppress larval populations of the annual bluegrass weevil, Listronotus maculicollis, was investigated under field conditions over a 3-year period (2006–2008). Combination of nematode species, application rate and timing produced strong numerical yet few statistically significant reductions. Steinernema carpocapsae Weiser, S. feltiae Filipjev, and Heterorhabditis bacteriophora Poinar applied at 2.5×10⁹ IJs/ha reduced first generation late instars between 69 and 94% in at least one field trial. Steinernema feltiae provided a high level of control (94%) to low densities (~20 larvae per 0.09 m²), but gave inadequate control for higher densities (24 and 50% suppression). No significant differences were found among treatment timings. However, applications timed to coincide with the peak of larvae entering the soil (fourth instars) generally performed better than applications made prior to (preemptive) or after the majority of the population advanced from the fourth instar. Nematode populations declined sharply between 0 and 14 days after treatment (DAT). Although nematode populations later increased (at 28 DAT), indicating an ability to recycle within hosts in the environment, they were nearly undetectable 56 DAT when the second generation host larvae were present in the soil. Applying commercially available nematode species at standard field rates cannot reliably reduce L. maculicollis immature densities on golf courses, nor will single applications suppress multiple generations. Future research will need to identify application strategies to improve biocontrol consistency.     

Efficacy of the entomopathogenic nematode, Steinernema feltiae, against Bemisia tabaci in relation to plant species

Abstract:  The use of infective juveniles (IJs) of the entomopathogenic nematode, Steinernema feltiae , to control the immature stages of the tobacco whitefly, Bemisia tabaci (Gennadius) (Hom., Aleyrodidae), on a range of host plants was investigated. Foliar applications of S. feltiae (10 000 IJs/ml) were made to tomato ( Lycopersicon esculentum ), cucumber ( Cucumis sativus ), poinsettia ( Euphorbia pulcherrima ), chrysanthemum ( Dendranthema spp.) and verbena ( Verbena hybrida ) infested with second instar B. tabaci , to determine whether efficacy was influenced by plant species. The effect of the adjuvants Agral, Triton X-100, methylcellulose, glycerol and spraying oil on the level of pest mortality was also assessed using two selected host plants, tomato and verbena. Following nematode application B. tabaci mortalities of 32, 28, 22 and 22% were recorded on tomato, cucumber, verbena and chrysanthemum, respectively, but a lower mean mortality was noted for whitefly feeding on poinsettia (10%). Mortality of B. tabaci on tomato and verbena was significantly increased by the addition of either Triton X-100 or Agral to the spray suspension. The use of Triton X-100 raised the mortality level to 63 and 37% on tomato and verbena, respectively, while 50 and 27% mortality followed the use of Agral on the two hosts. With the exception of glycerol no phytotoxic effects were observed by the adjuvants when applied to all five host plant species used in this study. The potential for use of the entomopathogenic nematode, S. feltiae , as a non-chemical alternative control measure for B. tabaci immatures is discussed.     

Host density effects on efficacy of entomopathogenic nematodes against white grub (Coleoptera: Scarabaeidae) species

We tested the effect of host density on entomopathogenic nematode efficacy in 1-L pots with grass and soil. In four experiments, combinations ranged from somewhat resistant hosts (oriental beetle, Anomala orientalis, or northern masked chafer, Cyclocephala borealis, with Heterorhabditis bacteriophora) over more susceptible hosts (Japanese beetle, Popillia japonica, with Steinernema glaseri) to a highly susceptible host (P. japonica and S. scarabaei). In each experiment, four larval densities were exposed to two nematode rates over a 14-day period. A significant effect of host density on nematode efficacy occurred only in the A. orientalis–H. bacteriophora combination, but there was no clear trend in the data. This suggests that an exhaustion of available nematode populations to less lethal levels by high host numbers was counteracted by other factors such as increased chances for nematode-host contact and increased host susceptibility due to stress via reduced food resources and increased aggression between larvae.     

昆虫病原线虫感染期幼虫恢复发育的研究进展

昆虫病原线虫的感染期幼虫（infective juvenile,IJ）是其一生中唯一具有侵染能力和可自由生活于寄主体外的虫态,一般滞育不取食,体外包裹着已经蜕去的第2龄幼虫的表皮,对外界不良环境的耐受能力强,又称为耐受态幼虫(dauer juvenile,DJ),类似于秀丽隐杆线虫Caenorhabditis elegans的耐受态幼虫。在食物信息的诱导下,感染期幼虫脱鞘,释放出共生细菌,恢复取食并继续发育,这个过程称为感染期幼虫的恢复（IJ recovery）。这个过程是发生在寄生性线虫入侵寄主时的发育过程,对于成功寄生是必要的,在线虫的产业化培养中发挥着重要作用,感染期线虫的恢复率及其发育的同步性直接影响了线虫的产量。本文概述了感染期线虫的恢复发育过程,并对诱导感染期线虫恢复发育的食物信号（food signals）、恢复的影响因素及其检测手段进行了综述,同时讨论了未来的研究方向。     

Production technology for entomopathogenic nematodes and their bacterial symbionts

Entomopathogenic nematodes (genera Steinernema and Heterorhabditis) kill insects with the aid of mutualistic bacteria. The nematode–bacteria complex is mass produced for use as biopesticides using in vivo or in vitro methods, i.e., solid or liquid fermentation. In vivo production (culture in live insect hosts) is low technology, has low startup costs, and resulting nematode quality is high, yet cost efficiency is low. In vitro solid culture, i.e., growing the nematodes and bacteria on crumbled polyurethane foam, offers an intermediate level of technology and costs. In vivo production and solid culture may be improved through innovations in mechanization and streamlining. In vitro liquid culture is the most cost-efficient production method but requires the largest startup capital and nematode quality may be reduced. Liquid culture may be improved through progress in media development, nematode recovery, and bioreactor design. A variety of formulations is available to facilitate nematode storage and application. Journal of Industrial Microbiology & Biotechnology (2002) 28, 137–146 DOI: 10.1038/sj/jim/7000230 Received 16 August 2001/ Accepted in revised form 10 November 2001