肾形肾状线虫（Rotylenchulus reniformis）浙江杭州 群体形态学和分子特性及寄主范围

 肾形肾状线虫（Rotylenchulus reniformis）是一种重要的蔬菜线虫,寄主范围和分布很广。本文根据形态学特征和形态测量将来自浙江省杭州市蔬菜上的肾状线虫群体鉴定为肾形肾状线虫,为浙江省首次报道。该群体的形态学特征及形态测量值与模式标本基本吻合,个别形态测量值(比值)有变异。通过对该肾形肾状线虫群体的rDNA中ITS区和编码28S RNA基因中的D2D3区的PCR扩增和序列测定,明确二序列长度分别为808 bp和786 bp;序列分析发现该群体ITS序列与肾形肾状线虫种内一些两性生殖群体的亲缘关系较近,同源性高达99.5%～100%,而与一孤雌生殖群体同源性为92.4%;编码28S RNA基因中的D2D3区与已报道群体的同源性达到99.4%,相似度较高;本研究还发现杭州肾形肾状线虫群体的寄主涉及11个科16个属的果蔬。     

Early stages of septoria tritici blotch epidemics of winter wheat: build‐up,overseasoning, and release of primary inoculum

Septoria tritici blotch (STB), caused by Mycosphaerella graminicola, is the most prevalent disease of wheat worldwide. Primary inoculum and the early stages of STB epidemics are still not fully understood and deserve attention for improving management strategies. The inoculum build‐up and overseasoning involves various fungal structures (ascospores, pycnidiospores, mycelium) and plant material (wheat seeds, stubble and debris; wheat volunteers; other grasses). Their respective importance is assessed in this review. Among the mechanisms involved in the early stages of epidemics and in the year‐to‐year disease transmission, infection by ascospores wind‐dispersed from either distant or local infected wheat debris is the most significant. Nevertheless, infection by pycnidiospores splash‐dispersed either from neighbouring wheat debris or from senescent basal leaves has also been inferred from indirect evidence. Mycosphaerella graminicola has rarely been isolated from seeds so that infected seed, although suspected as a source of primary inoculum for a long time, is considered as an epidemiologically anecdotal source. Mycosphaerella graminicola can infect a few grasses other than wheat but the function of these grasses as alternative hosts in natural conditions remains unclear. Additionally, wheat volunteers are suspected to be sources of STB inoculum for new crops. This body of evidence is summarized in a spatio‐temporal representation of a STB epidemic aimed at highlighting the nature, sources and release of inoculum in the early stages of the epidemic.     

Phenotypic and molecular genetic characterization indicate no major race‐specific interactions between Xanthomonas translucens pv. graminis and Lolium multiflorum

Bacterial wilt of forage grasses, caused by the pathogen Xanthomonas translucens pv. graminis (Xtg), is a major disease of forage grasses such as Italian ryegrass (Lolium multiflorum). The plant genotype‐bacterial isolate interaction was analysed to elucidate the existence of race‐specific responses and to assist the identification of plant disease resistance genes. In a greenhouse experiment, 62 selected plant genotypes were artificially inoculated with six different bacterial isolates. Significant differences in resistance were observed among L. multiflorum genotypes (P < 0·001) and in virulence (intensity of disease symptoms) among Xtg isolates (P < 0·001) using the area under the disease progress curve (AUDPC). No significant genotype‐isolate interaction (P > 0·05) could be observed using linear regression modelling. However, additive main effects and multiplicative interaction effects (ammi ) analysis revealed five genotypes which did not cluster close to the origin of the biplot, indicating specific interactions between these genotypes and some bacterial isolates. Simple sequence repeat (SSR) markers were used to identify marker‐resistance associations using the same plant genotypes and bacterial isolates. The SSR marker NFA027 located on linkage group (LG) 5 was significantly associated with bacterial wilt resistance across all six bacterial isolates and explained up to 37·4% of the total variance of AUDPC values. Neither the inoculation experiment nor the SSR analyses revealed major host genotype‐pathogen isolate interactions, thus suggesting that Xtg resistance, observed so far, is effective across a broad range of different bacterial isolates and plant genotypes.     

Evidence of host‐range expansion from new powdery mildew (Blumeria graminis) infections of triticale (×Triticosecale) in France

This study aimed to determine whether powdery mildew caused by Blumeria graminis is an endemic pathogen of triticale (×Triticosecale: Triticum × Secale), emerging as a result of recent changes in its pathogenicity, or whether it is a new pathogen, possibly resulting from hybridization between ff. spp. tritici and secalis. A secondary aim was to consider breeding practices that may have favoured this emergence. Phylogenetic analyses based upon six genes revealed the close relatedness of the novel entity and the ff. spp. tritici and secalis, but the IGS marker finally grouped together the isolates collected on triticale and on wheat, supporting the scenario of a recent host‐range expansion from wheat to triticale. Pathotype analyses concluded that virulence spectra of B. graminis infecting triticale were new in comparison to those observed for other reference formae speciales, and lack of fungicide resistance in triticale isolates strengthens the hypothesis of no or little genetic exchange between wheat and triticale populations of powdery mildew. This adaptation may follow the breakdown of plant resistance genes, which are probably not very diverse in current triticale cultivars since this criterion was not considered as a major one until recent years. Moreover, the complex selection and genetics of this hybrid cereal makes it difficult to predict the transmission of powdery mildew resistance genes.     

玉米螟长距茧蜂人工繁殖研究初报

文本报道了人工繁殖玉米螟长距茧蜂的几个重要问题.提出采用3龄或4龄的玉米螟幼虫作中间寄主繁殖该蜂最为适宜;接蜂时间应该达到3～4天(种蜂羽化当天接蜂),才能获得较高的寄生率;在温度为摄印5±1的条件下,繁殖一代需要33天;人工繁殖代数增加,长距茧蜂的生活力有下降趋势。文末,对人工繁殖的玉米螟长距茧蜂生活力较低的原因也进行了分析讨论。     

禽流感病毒的宿主特异性和致病性分子基础

禽流感病毒可感染许多鸟类和哺乳动物,但是其自然宿主范围通常限于野生水禽,如野鸭、海鸥等。近年来出现新的特征,可以感染人类、猫、虎等动物,突破了宿主限制性,出现种间传播。这与其宿主特异性变化和致病力变异有关。为此,依据禽流感病毒的致病特性、抗原蛋白(血凝素蛋白HA)特性和宿主细胞受体特点,结合其它影响因素,阐述了流感病毒的宿主特异性和致病性分子基础,以进一步认识禽流感病毒。     

岛弯尾姬蜂的寄主搜索行为

利用双选择试验 ,研究岛弯尾姬蜂的寄主选择行为。结果表明 :新手寄生蜂的寄主搜索并不活跃。接触植株的虫害伤口能有效激活该寄生蜂的寄主搜索行为和效率 ,但对仅接触隔离于植株的寄主和机械损伤的植株作用不大。具有效经历的岛弯尾姬蜂明显趋向粉纹夜蛾或小菜蛾为害的植株 ,但仍不能分辨带有小菜蛾幼虫排泄物的苞菜、受机械伤害和甘蓝跳甲为害的植株。并对该蜂寄主搜索的影响因子进行了探讨     

牡丹、芍药根结线虫种的鉴定及防治初报

1986～1988年,系统观察了牡丹、芍约根结线虫病害的症状。发现根结线虫侵染牡丹、芍药的营养根,不侵染主根系。发病严重的植株,单株根结重量可达300～400g;形态学研究证明:牡丹根结线虫为北方根结线虫(Meloidogyne hapla);芍药根结线虫为南方根结线虫(M.incognita)。牡丹、芍药田间的许多杂草是据结线虫的野生寄主。初步防治试验认为:秋季(9月中旬),分根移栽时,用40%甲基异柳磷乳油杀线剂1000倍液浸根10min,防效为75%。在生长季(4月下旬),用10%克线磷或15%涕灭威颗粒杀线剂处理田间土壤,防效分别为62%,74%左右。     

白术根腐病的研究 Ⅰ.病原菌鉴定、生理生化特性及寄主范围

1986～1989年从湖南、浙江、江西3省23个县(市)采集白术根腐病病株样本231个,分离、接种获得单孢致病菌株29个,经鉴定其致病菌为尖镰孢菌(Fusarium oxysporum S chl.)和半裸镰孢菌(Fusariccm Semitectum Berk & Rav.),前者占多数,病菌生长最适温度为25～30℃,最适pH值为4.0～9.0;在PA培养基上产生大分生孢子最多;氮源以L-亮氨酸、L-(+)天冬氨酸、γ-氨基丁酸最好;碳源以葡萄糖、D-果糖、L-树胶醛糖为最好.寄主范围广,病菌在病残体上存活期在4年以上.     

山东盾蚧首科（同翅目：蚧总科）考

本文以多年来采集积累的标本为基础，考证了山东省后蚧首科状况，山东只有盾蚧科（Ｄｉａｓｐｉｄｉｄａｅ）１科，其种类计达５族２６属５０种。