飞机草提取物对红脉穗螟的产卵忌避及杀卵活性

为探讨飞机草提取物对红脉穗螟Tirathaba rufivena Walker的防控潜力,采用室内生物测定法,研究了飞机草提取物对红脉穗螟的产卵忌避作用和杀卵活性。结果表明,飞机草乙酸乙酯提取物对红脉穗螟的忌避效果最好,选择性和非选择性忌避率分别为41.85%和46.84%;不同提取物处理红脉穗螟的卵后,均造成卵孵化率降低和初孵幼虫的死亡,其中乙酸乙酯提取物对红脉穗螟卵的影响最大,孵化率和1龄幼虫死亡率分别达到65.89%和40.37%。对飞机草乙酸乙酯提取物进行分级萃取测试各萃取物的活性发现,正己烷萃取物对红脉穗螟的产卵忌避作用和杀卵活性最强。田间试验表明,采用正己烷萃取物稀释50倍和100倍浓度进行田间喷雾,药后15 d对红脉穗螟的种群控制率可达到50%以上。     

外来入侵种飞机草在不同环境胁迫下抗氧化酶系统的变化

飞机草（Eupatorium odoratum）原产于中南美洲,在我国最早发现于1934年,目前已经分布到云南、海南、台湾、广东等省区,是一种典型的外来入侵种。研究其在逆境条件下的生理适应机制对于有效治理该入侵种具有十分重要的意义。研究了其在不同环境胁迫条件（高温、低温和干旱）下抗氧化酶系统的变化。结果表明：超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）和脱氢抗血酸还原酶（DHAR）在3种环境胁迫下酶活性都升高;过氧化氢酶（CAT）在高温胁迫下升高,而在低温和干旱胁迫下酶活性降低;过氧化物酶（POD）和单脱氢抗坏血酸还原酶（MDAR）在高温和干旱胁迫下酶活性升高,而在低温胁迫下酶活性降低;谷胱甘肽还原酶（GR）在高温和干旱胁迫下酶活性升高,而在低温胁迫下保持不变。这些研究结果可能有助于寻找到一条控制飞机草的新途径。     

不同生境条件下紫茎泽兰化感作用的变化与入侵力关系的研究

 在紫茎泽兰(Eupatorium adenophorum)入侵地,草本层中的本地植物的多度和盖度与紫茎泽兰的多度和盖度具有显著的负相关关系,落叶阔叶林和公路边生境的紫茎泽兰相对多度和盖度为常绿阔叶林生境的3～5倍;而本地草本植物在组成种类、相对多度和盖度在落叶阔叶林和公路边生境比常绿阔叶林生境减少了30 %、50 % 和70 %。用生物检测的方法研究常绿阔叶林、落叶阔叶林、公路边——３个不同生境下的紫茎泽兰根和茎的水浸提液的化感作用表明：不同生境的紫茎泽兰茎和根的化感作用存在差异,即公路边>落叶阔叶林下>常绿阔叶林下,关联分析显示出不同生境条件下的化感作用力与本地植物的相对多度存在显著的相关关系,证明不同生境的化感作用的差异是紫茎泽兰的入侵效果的原因之一;在白菜(Brassica rapa)幼苗生物量生长抑制试验中,各样地的茎提取液处理的白菜幼苗生物量之间的差异大于各样地的根提取液处理之间的差异,说明对于不同样地的紫茎泽兰的入侵力,地上部分的化感作用比地下部分具有更大的贡献力。落叶阔叶林下和公路边的紫茎泽兰生长旺盛、现存单位面积生物量远远高于常绿阔叶林下,这将促使落叶阔叶林和公路边生境的单位面积上的紫茎泽兰种群的化感作用大于常绿阔叶林下的紫茎泽兰种群,使落叶阔叶林和公路边生境的本地植物群落比常绿阔叶林下的本地植物群落面临较大的竞争压力,加速落叶阔叶林下和公路边生境的本地植物群落的衰退。     

紫茎泽兰对五种苦苣苔科植物化感作用的初步研究

紫茎泽兰（Eupatorium adenophorum）为菊科一种入侵性极强的外来杂草, 现已在我国西南部地区蔓延生长, 并侵入多种苦苣苔科植物的生境。中国苦苣苔科植物均已收入《中国物种红色名录》, 其中部分已被列为国家重点保护物种。为了解紫茎泽兰对本土苦苣苔科植物生长的影响, 作者分别采用其根、茎、叶水提液(8%)对3属5种苦苣苔科植物, 即刺齿唇柱苣苔（Chirita spinulosa）、荔波唇柱苣苔（C. liboensis）、烟叶唇柱苣苔（C. heterotricha）、芒毛苣苔（Aeschynanthus acuminatus）和台闽苣苔（Titanotrichum oldhamii）的幼苗进行处理。结果表明, 紫茎泽兰叶水提液对刺齿唇柱苣苔、荔波唇柱苣苔和烟叶唇柱苣苔均有不同程度的化感作用, 其中对刺齿唇柱苣苔的化感作用最为明显, 当叶水提液在培养基中的浓度为2.4%、3.2%和4.0%时, 刺齿唇柱苣苔幼苗的生长完全受到抑制。紫茎泽兰的茎水提液对台闽苣苔有一定程度的化感作用, 当提取液在培养基中的浓度为1.6%时, 对台闽苣苔幼苗生长的抑制效应达到40%。紫茎泽兰叶和茎水提液对芒毛苣苔幼苗生长无明显的化感作用, 紫茎泽兰根水提液对5种苦苣苔科植物也均无显著影响。由此可知, 紫茎泽兰对唇柱苣苔属和台闽苣苔属的植物有一定的化感作用, 而对于芒毛苣苔属无明显的影响。分析结果显示, 紫茎泽兰对岩生苦苣苔科种类要比附生于树上的近缘种化感作用更为明显。     

泽兰叶上的三种真菌

本文报道采自北京、安徽和云南泽兰属(Eupatorium spp.)叶上的三种真菌,其中有一个新种:泽兰齿梗孢(Scolecobasidium eupatorii Guo,sp.nov.)和一个新组合:藿香蓟假尾孢[Pseudocercospora ageratoides(Ell.& Ev.)Guo,comb.nov.]。新种与Sco-lecobasidium anelii和S.arenarium之区别在于S.anelii分生孢子梗短(35.0μm),分生孢子有纵隔膜,常在隔膜处缢缩;S.arenarium分生孢子的隔膜色泽深,在孢子的一端或两端具黑点。研究的标本收藏在中国科学院微生物研究所真菌标本室(HMAS)。     

Effect of cross proximity on progeny fitness in a rare and a common species of Eupatorium (Asteraceae)

Offspring from matings between near neighbors may exhibit lower fitness relative to offspring from more distant matings due to spatial structuring of populations resulting from limited dispersal of pollen and seed. This response, which can be interpreted as inbreeding depression, is studied in the rare species, Eupatorium resinosum, and a closely related congener, E. perfoliatum, through the use of hand pollinations representing three distance classes (near-within a population, far-within a population, and between populations) and an assay of the offspring in an experimental plot. Early traits such as seed mass and first-year stem length were not significantly affected by the cross type, although they were affected by maternal parentage. Size and reproduction in the second field season increased with increased pollen donor distance from the maternal plant. Cross type was significant for many traits in the second field season, indicating inbreeding depression in crosses of neighbors (for E. resinosum) and hybrid vigor between populations (both species). This suggests that the rare species, E. resinosum, had a more spatially structured population than E. perfoliatum. The implications of these results for conservation of rare species indicate that protection of habitats sufficient for large populations is necessary to maintain genetic diversity since each population likely consists of many smaller subpopulations.     

Microclimate above grass adversely affects spring growth of seedling snow gum (Eucalyptus pauciflora)

Growth of snow gum seedlings (Eucalyptus pauciflora Sieb. ex Spreng.) was studied in response to differences in microclimate caused by differential heat exchange between seedlings, grass and bare, moist soil during winter and spring. Seedlings were planted in a pasture either directly into grassy groundcover or in circular patches of bare soil of 30, 60 or 120 cm in diameter. There were no differences in maximum air temperatures at seedling leaf height between treatments. However, minimum air temperature increased by 2 °C with increase in patch diameter from 0 to 120 cm such that seedlings surrounded by grass experienced lower minimum temperatures with more frequent and more severe frosts than seedlings growing in large patches of bare soil. These small-scale differences in minimum temperature affected both photosynthetic and growth processes. Over winter, seedlings were photoinhibited, with depression in midday F_v/F_m linearly related to minimum temperatures. In spring, repeated frosts and lower minimum temperatures led to a delay in the recovery of F_v/F_m, a delay in bud-break, damage to elongating stems and developing leaves, lower rates of stem elongation, and ultimately a shorter growing season for seedlings in grass compared to those in bare soil patches. Thus, microclimate above grass adversely affects spring growth of juvenile Eucalyptus pauciflora and may account for much of the competitive inhibition of tree seedling growth by grass during spring.     

Molecular phylogeny of geminivirus infecting wild plants in Japan

Few studies have been made on the molecular divergence of plant viruses. To remedy this deficiency, we examined the molecular divergence of the tobacco leaf curl geminivirus (TLCV). TLCV infects not only tobacco but alsoEupatorium andLonicera in the field and causes yellow vein disease. A total of 29 nucleotide sequences of the replication protein gene (ORF C1) of geminiviruses infecting wild plants ofE. makinoi, E. glehni andL. japonica collected from ten localities was determined. Highly divergent sequences were obtained not only among host plant populations but also within a host population. Phylogenetic analyses showed that the TLCVs infectingEupatorium andLonicera were clustered into three different clades, and were either paraphyletic or polyphyletic. This result is the first evidence demonstrating that wild populations of single plant species possess genetically diversified virus strains. Comparison with recently reported genetic variations of tobacco mild green mosaic tobamovirus (TMGMV) revealed three characteristics of TLCV evolution: (1) a higher nucleotide substitution rate, (2) more frequent migration among geographically isolated host populations, and (3) more frequent host changes to different plant families. While TMGMV is an RNA virus, TLCV has DNA genomes. In animal viruses, RNA viruses tend to evolve faster than DNA viruses. Our results indicated that this trend may not hold for plant viruses.     

Effects of geminivirus infection and growth irradiance on the vegetative growth and photosynthetic production of Eupatorium makinoi

Eupatorium makinoi plants with or without geminivirus infection were grown in shading frames with 70, 15 and 5.5% sunlight. Growth characteristics of these plants in the early vegetative phase were compared by means of growth analysis. We also measured leaf photosynthetic gas exchange rates and examined relationships between leaf photosynthesis and whole-plant growth. Relative growth rate (RGR=(1/W)×(dW/dt), where W is plant dry mass) of virus-infected plants was lower than that of uninfected plants under all three light conditions. The reduction of RGR by infection was increased with irradiance. The net assimilation rate (NAR=(1/A)×(dW/dt), where A is total leaf area of the plant) was also reduced both by infection and shading. NARs that were estimated from light-response curves of leaf photosynthesis, in situ measurements of irradiance, and respiration rates of leaves, stems and below-ground parts, agreed very well with the values obtained by conventional growth analysis techniques. Decreases in the estimated NAR value from infection and shading were mostly explained by the decreases in leaf photosynthesis. These results clearly showed that lowered RGR in virus-infected plants was attributed mainly to impaired photosynthesis in virus-infected leaves.     

世界性恶性杂草──紫茎泽兰研究的历史及现状

紫茎泽兰又名破坏草,其学名为Eupalo,。u。。ade;;opho;、。nSprengel,［Age。t。naade。;opho;a（Spreng．）K．＆R,E．glandulosumH．B．K．nonMichx．j,英文名为Croftonweed或Pamakani,菊科泽兰属多年生杂草。原产美洲的墨西哥至哥斯达黎加一带,后作为观赏植物被引种到欧洲"',后再引到澳洲和亚洲'"。显然,长距离的传播是借助于人的力量。不过,短距离传播扩散都是由其自身的瘦果扩散能力,经风力完成的'"。现已广泛分布在世界热带、亚热带地区30多个国家和地区。除中美洲原产地外,其中还包括美国'"'、澳大利亚","…