南京毛刺线虫对山定子的直接致病性研究

北京南口农场山定子砧苹果树受线虫侵害严重。田间树势调查结果表明:病树长势衰退,产量降低,品质下降;补植的幼树表现出再植病症状。田间根系症状调查结果表明:病树根系生长异常,表现出典型的短粗根病症状,即受害幼根不呈延伸生长,而是在生长中不断分枝,以致最后形成须状丛簇根,每年只在新根旺长期长出一小段具有吸收功能的白色、毛笔尖状的新根。盆栽幼苗接种试验表明:南京毛刺线虫的侵染严重影响了山定子幼苗的形态建成,且使根系表现出短粗根病症状,从而证明南京毛刺线虫(Trichodorus nanjingensis Liu＆Chen)是导致该场苹果树势衰退、再植病和短粗根病的主要病原。     

Molecular characterization and diagnostics of stubby root and virus vector nematodes of the family Trichodoridae (Nematoda: Triplonchida) using ribosomal RNA genes

Plant parasitic nematodes of the family Trichodoridae cause substantial yield losses in many agricultural crops. Rapid and accurate identification of trichodorids to the species level is critical for selection of appropriate measures for control. This study analysed 99 sequences of the D2–D3 expansion segments of the 28S rRNA gene and 131 sequences of the 18S rRNA gene from the stubby nematodes belonging to the genera Nanidorus, Paratrichodorus and Trichodorus. Species delimiting was based on the integration of morphological identification, which is not provided in the present article, and molecular‐based phylogenetic inference and sequence analysis. Twenty‐two valid species and several species complexes were identified among nematodes included in the analysis. PCR‐RFLPs of the partial 18S rDNA and the D2–D3 expansion segments of the 28S rDNA were tested and proposed for identification of these nematodes. Gel PCR‐RFLP profiles and tables with restriction fragment lengths for several diagnostic enzymes are provided for identification. Some problems of taxonomy and phylogeny of nematodes of the family Trichodoridae are also discussed.     

温度、光照对南京裂爪螨的影响

南京裂爪螨 (Schizotetranychus nanjingensis Ma et Yan)常与竹缺爪螨 (Aponychuscorpuzae Rimando)、竹裂爪螨 (Schizotetranychus bambusae Recb)等害螨共同或单独在毛竹(Phyllostachys pubescens Mazel et H.de L ehaie)叶背刺吸危害 ,造成竹叶早衰、早落[1～ 3] 。有关其生活习性及其发生与部分环境因子的关系以及防治技术 ,前人已作了研究[3～ 9] ,但未见光照对其存活、发育、繁殖的影响以及温度与其存活的关系等文献报道 ,本文就此作一研究报道。1　材料与方法1 .1　温度试验设置 - 1 0℃± 1℃、2℃± 1℃、2 0℃± 1℃、2 5℃…     

Molecular diagnostics of some trichodorid nematodes and associated Tobacco rattle virus

Several Paratrichodorus and Trichodorus (trichodorid) nematode species are natural vectors of Tobacco rattle virus (TRV) and cause economically important diseases, especially in potato and ornamental bulbous crops. Identification of trichodorid species based on morphological characters is laborious, time-consuming, and requires the services of highly trained personnel. Molecular diagnostics for trichodorid nematodes, using the ribosomal DNA repeat unit, were successfully developed to distinguish two Paratrichodorus and two Trichodorus species. The complete sequences of the 18S genes and the ITS-1 regions for these species were obtained and species-specific primers successfully designed for them. An RT-PCR assay was developed utilizing isolate-specific primers that amplify serologically distinguishable strains of TRV in individual trichodorid nematodes. The primers were based on the highly conserved RNA-1 segment of the bipartite genome and also on different parts of the RNA-2 segment of the virus genome.     

山定子幼苗根尖感染南京毛刺线虫后的组织变化

对山定子（MainsbaccataBorkh．）幼苗根尖组织的显微和超微结构观察结果表明：在遭到南京毛刺线虫（Trichodorusnajinjensis）侵染以后,被直接取食的细胞死亡,表现出细胞壁严重变形,部分分解,细胞器消失,整个细胞空间呈电子透明或仅在靠近细胞壁处存在少量电子密集的物质;未遭到直接取食但与死亡细胞邻近的细胞也发生畸变,这些均对根尖分生组织造成了破坏,导致根尖细胞死亡,并诱发丛簇根,这从组织学角度阐明了山定子幼苗感染南京毛刺线虫后发生短粗根病的成因。     

毛刺线虫（Nematoda：Trichodoridae）的调查鉴定

在江苏、安徽和湖南的(22份)毛刺线虫(T_(1-22))土样中,T_(14)样本的雌虫以及T_6、T_7中的少数雌虫鉴定为 Paratrichodorus porosus。T_(21)的毛刺线虫采自江苏南京桃根周围,定为 Trichodorus nanjingensis n.sp.。T.nanjingensis n.sp.与 T.complexus、T.borneoensis 最相似,它们都有2枚前于排泄孔的腹颈乳突、3枚生殖乳突和细纹化的交合刺,但新种的交合刺形态和仅1枚生殖乳突在交合刺区分别与后二者不同。新种阴道骨化结构的形态和没有明显分化的受精囊,也都有别于 T.complexus 和 T.borneoensis。     

广州毛刺线虫新种的描述

 广州毛刺线虫新种(Trichodorus guangzhouensis n. sp.)采集于广州市白云区的莴苣(Lactuca sativa)根际土壤。其主要鉴别特征是虫体和瘤针较短;雄虫的3个腹中颈乳突位于瘤针后和排泄孔前,交合刺短、无刚毛和条纹,泄殖腔前有3个腹中生殖乳突,精细胞大、有大且呈香肠形的核;雌虫阴门纵裂,阴门骨化结构小、三角形到园三角形、相距较近,阴道长度大于阴门处体宽的1/3,受精囊大、有精子。该新种在多数形态特征测量数据上,以及雄虫的3个腹中颈乳突位置、泄殖腔前腹中生殖乳突数量、精细胞形态,雌虫受精囊和阴门骨化结构形态等特征上,与背弯毛刺线虫(Trichodorus reduncus Siddiqi & Sharma,1995)相近似。但它们在雄虫交合刺和引带形态、第一腹中生殖乳突(SP1)的位置,雌虫阴门形态等特征上存在显著差异。     

香蕉上的新纪录雪松毛刺线虫描述

本文对中国云南河口香蕉上的雪松毛刺线虫(Trichodorus cedarus Yokoo)的形态特征进行了描述,其测计值与我国文献记载的杉木、桃、苹果和梨树种群相关测计值比较,香蕉种群的雌雄虫虫体平均长度和b值偏大,口针平均长度较杉木和桃上种群的短,长于苹果和梨树上的种群。该线虫在香蕉根围土发现尚属首次。     

松材线虫病死木皮下的南京隐翅虫(鞘翅目:隐翅虫科)

【目的】南京隐翅虫是在受松材线虫病危害的病死木皮下发现的隐翅虫新种,与小蠹、天牛等多种次期性害虫的时间和空间生态位跟随关系密切,具有作为媒介昆虫防治蛀干害虫的潜力。研究南京隐翅虫不同发育阶段个体的形态特征、成虫的食性及昼夜活动节律,能够为进一步的研究和应用提供参考。【方法】室内观察南京隐翅虫不同发育阶段个体的形态特征,通过人工饲养并结合口器解剖研究南京隐翅虫成虫的食性;应用"陷阱法"观察试虫的昼夜活动节律。【结果】南京隐翅虫幼虫为寡足型,口器咀嚼式,胸足发达,蛹为裸蛹,成虫体长1.5～2.0 mm,身体狭长平行,头、中后胸、腹部6～8节颜色较深,身体其他部分浅黄色。成虫喜食人为杀死的跳虫成虫、蝇科幼龄幼虫及天牛幼虫,对于小蠹科、象甲科、叩甲科、蚁科、蠼螋科的幼虫尸体表现出取食行为,试验过程中并未观察到捕食其他生物活体。室内南京隐翅虫成虫昼夜活动节律高峰期分别是8:00—11:00以及20:00—22:00。【结论】南京隐翅虫成虫为尸食性,其昼夜活动节律受温度影响较大。     

山定子感染南京毛刺线虫后几种生理生化物质的变化

 山定子(Malus baccata Borkh.)在遭到南京毛刺线虫(Trichodorus nanjingensis Liu & Chen)侵染以后,根尖组织中很多生理生化物质都发生了病态的变化。结果表明:处理和对照相比,游离脯氨酸(Pro)含量、还原糖(RC)含量、过氧化物酶(POD)活性、多酚氧化酶(PPO D)活性、苯丙氨酸解氨酶(PAL)活性和细胞壁中羟脯氨酸(Hyp)含量均有不同程度的增加,总糖含量降低;并且在侵染初期和侵染后期,各种物质的变化幅度不同,游离脯氨酸含量、还原糖含量、3种酶活性在侵染前期增加的幅度大,细胞壁中羟脯氨酸含量是侵染后期增加的幅度大,而总糖含量是侵染后期降低的幅度大。这些物质的变化趋势揭示了山定子感染南京毛刺线虫的病症生理。