寄主植物对桑寄生植物叶片功能性状的影响

为了解寄生植物叶片功能性状的差异及其影响因素,研究了西双版纳地区寄主植物对3种桑寄生植物叶片功能性状的影响,并分析了桑寄生植物与寄主植物叶片功能性状的相关性。结果表明,不同寄主植物的相同寄生植物叶片功能性状存在显著差异,来自7种寄主植物的五蕊寄生(Dendrophthoe pentandra)的叶片含水量(61.2%～70.1%)、氮含量(9.6～16.0 g/kg)、碳氮比(30.8～48.5)以及缩合单宁含量(3.3%～11.0%)等性状的差异较大;从4种寄主植物上获取的澜沧江寄生(Scurrula chingii var.yunnanensis)的叶片含水量(60.0%～71.7%)、碳含量(431.3～502.3 g/kg)和缩合单宁含量(3.8%～9.9%)等性状也呈现较大种间差异,而在2种寄主植物上的离瓣寄生(Helixanthera parasitica)的叶片功能性状没有显著差异。桑寄生植物与寄主植物的叶片含水量、总碳含量、总氮含量、碳氮比和缩合单宁含量呈显著的正相关。寄主植物作为桑寄生植物营养物质的主要来源,会影响桑寄生植物叶片的相应功能性状。桑寄生植物能从寄主植物获...     

寄主植物物理性状及营养物质对地红蝽寄主选择性的影响

【目的】地红蝽Pyrrhocoris tibialis是一种重要的农业植食性害虫,寄主范围广泛。本研究测定地红蝽对不同植物的取食偏好及分析寄主植物物理性状和营养物质在地红蝽成虫寄主选择行为中的作用,以期从寄主理化性状的角度来探讨地红蝽寄主选择行为机制,为指导作物抗虫育种提供依据。【方法】通过自由选择方法研究地红蝽成虫对5种寄主植物(谷子Setaria italica、高粱Sorghum bicolor、绿豆Vigna radiata、大豆Glycine max和玉米Zea mays)叶片的取食选择性;使用Y型嗅觉仪进一步检测地红蝽对5种植物叶片气味的趋性反应;测定分析5种植物叶片物理性状及主要营养物质含量与地红蝽取食选择性的相关性。【结果】地红蝽成虫对5种寄主植物叶片的取食选择率存在显著性差异,依次为谷子＞高粱＞绿豆＝大豆＞玉米,与对这5种寄主植物叶片气味的趋性反应百分率结果一致。相关性分析表明,地红蝽成虫的取食选择性与叶片长宽比、含水量和背面茸毛密度呈显著正相关,相关系数分别为0.881, 0.884和0.906,而与地红蝽成虫取食前后寄主植物叶片可溶性糖含量变化和总蛋白质含量变化呈显著负相关,相关系数分别为-0.915和-0.951。通径分析表明,寄主植物叶片背面茸毛密度和总蛋白质含量变化是地红蝽寄主选择性的重要决定因素。【结论】地红蝽成虫对不同寄主植物存在取食选择和趋向性差异,地红蝽成虫取食选择与寄主植物叶片长宽比、背面茸毛密度、含水量以及可溶性糖和总蛋白质含量变化有关。     

虾钳菜日龟甲的生物学及寄主专一性研究

虾钳菜日龟甲 Cassida japana Baly是农田杂草藜 Chenopodium album L.的重要天敌。该虫在江苏地区一年发生4代,以成虫越冬。成虫产卵期一般为16～31 d,每雌产卵量最多为482粒,平均为175粒。各虫态历期因代别而异,卵期3～13d,幼虫期8～16 d,蛹期3～6 d,成虫寿命一般为15～35 d,越冬代成虫寿命长达200余d。该虫全年盛发期在6月中、下旬至8月中旬,发生为害与温度关系密切,高温对其不利。本文选择15科26种植物进行寄主专一性测定,结果表明：虾钳菜日龟甲对藜的嗜食程度很高,并能在藜上完成世代;而其它供试植物不是虾钳菜日龟甲的寄主,因此可以将该虫安全用于杂草藜的生物防治。     

不同寄主桑寄生中化学成分的差异性分析CSCD

为了探讨寄主植物对桑寄生代谢物合成积累的影响,本文采用超快速液相色谱-三重四极杆飞行时间串联质谱(UFLC-Triple TOF-MS/MS)结合多元统计分析技术对不同寄主来源桑寄生中化学成分差异性进行研究。通过二级串联质谱分析,对其质谱数据进行峰匹配、峰对齐、滤噪处理等,并进行特征峰提取;用主成分分析(PCA)和偏最小二乘法-判别分析(PLS-DA)处理数据;根据一级质谱精确质荷比和二级质谱碎片信息,结合软件数据库搜索、标准品比对及相关文献进行成分鉴定。结果显示,10个不同寄主来源桑寄生样品的化学组成得到有效区分;初步筛选并鉴定出19个差异化学成分,其中4种共有差异化学成分呈现出不同的变化规律。本研究为揭示寄主植物对桑寄生代谢产物合成和积累的影响以及不同寄主桑寄生质量评价提供基础资料。     

吃遍世界的桑寄生科植物

~~吃遍世界的桑寄生科植物@汪劲武     

用遗传工程技术改变根瘤菌寄主专一性

豌豆根瘤菌质体pJB5J1转移到Rh.trifolii菌株中建成了杂种菌株,它可使豌豆形成根瘤,从大型带色素的根瘤中分离到根瘤菌,不仅在豌豆上,而且在三叶草上形成具有固氮能力的根瘤,说明这种杂种菌带有nod~+和fix~+基因,然而固氮表型的丧失也是可逆的。     

广东省榕树虫瘿蓟马种类及营瘿蓟马寄主专一性调查

2013年对广东地区榕树虫瘿中的蓟马种类进行了调查,共发现榕母管蓟马Gynaikothrips ficorum(Marchal)、榕管蓟马Gynaikothrips uzeli(Zimmerman)、榕端宽管蓟马Mesothrips jordani Zimmermann、拉马棘腿管蓟马Androthrips ramachandrai Karny和黄胫棘腿管蓟马Androthrips monsterae(Moulton)5种管蓟马科种类,其中黄胫棘腿管蓟马为中国新纪录种。榕母管蓟马和榕管蓟马为营瘿蓟马,诱导初始虫瘿具有寄主专一性,榕母管蓟马是细叶榕Ficus microcarpa初始虫瘿的诱导者,而榕管蓟马仅在垂叶榕Ficus benjamina Linn.上诱导形成虫瘿;但当两种榕树种植在一起时,榕母管蓟马和榕管蓟马偶尔会入侵到对方成熟虫瘿中并与之生活在一起。榕端宽管蓟马属于盗寄生种类,而拉马棘腿管蓟马和黄胫棘腿管蓟马主要捕食营瘿蓟马的幼体(包括卵、若虫和\"蛹\"),三者均为寄居性蓟马,无寄主专一性。     

寄主植物叶片物理性状对潜叶昆虫的影响

潜叶昆虫广泛分布于鳞翅目、双翅目、鞘翅目和膜翅目中,其幼虫潜入叶片内部生活和取食,是一类用于研究植物-昆虫-天敌种间关系和协同进化的重要模式生物。有些潜叶昆虫是重要农林害虫。相比外食性昆虫,在叶内取食的潜叶昆虫幼虫更易受到叶片物理性状的直接影响。叶片的着生位置、朝向、大小、颜色和表皮毛等直接决定潜叶虫成虫的取食和产卵选择,从而影响幼虫的空间分布和寄主适应。叶片的某些物理性状也会直接影响幼虫的取食行为、生长发育和被寄生率。研究叶片物理性状的防御作用以及潜叶昆虫对这些防御的适应,有助于了解潜叶昆虫-寄主植物的协同进化。另一方面,外界环境和遗传育种都有可能改变植物叶片的物理特性,而对潜叶害虫产生抗性,从而实现潜叶害虫的可持续生态控制。     

广聚萤叶甲成虫取食经历对后续产卵寄主选择的影响

【背景】取食经历对植食性昆虫的寄主选择行为具有较大影响,影响天敌昆虫寄主专一性测定的设计和结果解释。【方法】采用选择性试验,观察了入侵豚草的重要天敌——广聚萤叶甲成虫羽化后取食不同植物对其后续产卵寄主选择的影响。【结果】与取食豚草的试虫相比,有取食三裂叶豚草、苍耳或菊芋经历的成虫选择苍耳产卵的频次增加,不再对豚草表现出明显的选择偏好性。对产卵识别期的Cox模型分析结果表明,成虫早期取食不同植物,对后续产卵选择有显著影响,成虫羽化后如果先取食豚草或三裂叶豚草,则选择苍耳产卵的倾向显著低于豚草;但如果先取食苍耳、菊芋和农家向日葵,则选择苍耳产卵的倾向与豚草无显著差异。【结论与意义】由此推测,广聚萤叶甲初羽化成虫取食的植物对其后续产卵选择具有较大影响,因而在寄主专一性测定中应关注测试前饲喂的植物种类。     

植物功能性状对土壤保持的影响研究述评

植被对土壤保持具有重要的影响,但是从植物功能性状的角度总结评述植被对土壤保持影响的研究并不多见。总结评述了植物地上功能性状、地下功能性状对土壤保持功能的影响以及植物地上、地下功能性状的关系,认为:(1)植被地上部分功能性状对土壤保持的作用主要体现在对溅蚀、面蚀的影响及间接改变土壤理化性质等方面,其功能性状指标主要包括叶面积、叶长、叶宽、枝数、植被高度等;(2)植被地下部分功能性状对土壤保持的作用主要体现在固持土壤、提高土壤抗剪切强度、提高土壤抗侵蚀能力、增强土壤渗透性,植物根系固持土壤与根系抗拉能力密切相关,植物根系土壤的物理和水文性质,与细根比例、根长密度、根表面积等性状密切相关;(3)可以通过植物地上部分功能性状间接反映地下部分功能性状,但是现有研究多为定性认识;(4)在植物功能性状对土壤保持的研究中亟待加强植被地上地下功能性状的长期定位监测,深化植被功能性状尤其是根系特征与土壤保持的作用机理,加强植被地上部分、地下部分功能性状的定量表达,建立植被功能性状与土壤保持功能的定量关系,实现植被功能性状与土壤保持功能特征的动态链接。     

Novel application of species richness estimators to predict the host range of parasites

Host range is a critical life history trait of parasites, influencing prevalence, virulence and ultimately determining their distributional extent. Current approaches to measure host range are sensitive to sampling effort, the number of known hosts increasing with more records. Here, we develop a novel application of results-based stopping rules to determine how many hosts should be sampled to yield stable estimates of the number of primary hosts within regions, then use species richness estimation to predict host ranges of parasites across their distributional ranges. We selected three mistletoe species (hemiparasitic plants in the Loranthaceae) to evaluate our approach: a strict host specialist (Amyema lucasii, dependent on a single host species), an intermediate species (Amyema quandang, dependent on hosts in one genus) and a generalist (Lysiana exocarpi, dependent on many genera across multiple families), comparing results from geographically-stratified surveys against known host lists derived from herbarium specimens. The results-based stopping rule (stop sampling bioregion once observed host richness exceeds 80% of the host richness predicted using the Abundance-based Coverage Estimator) worked well for most bioregions studied, being satisfied after three to six sampling plots (each representing 25 host trees) but was unreliable in those bioregions with high host richness or high proportions of rare hosts. Although generating stable predictions of host range with minimal variation among six estimators trialled, distribution-wide estimates fell well short of the number of hosts known from herbarium records. This mismatch, coupled with the discovery of nine previously unrecorded mistletoe-host combinations, further demonstrates the limited ecological relevance of simple host-parasite lists. By collecting estimates of host range of constrained completeness, our approach maximises sampling efficiency while generating comparable estimates of the number of primary hosts, with broad applicability to many host-parasite systems.     

Host specialization in habitat specialists and generalists

Generalists and specialists use different cues to find their habitat and essential resources. While generalists have the advantage of exploiting a wider range of resources, they are predicted to be less efficient in using one particular resource compared to specialists. The level of specialization of parasitoids can be either at the habitat or at the host level; strategies used by either type are expected to differ. We examined interactions between three aphid parasitoid species that are a habitat specialist Aphidius rhopalosiphi, a habitat generalist Aphidius ervi, and a host generalist Praon volucre on three cereal aphids, Sitobion avenae, Metopolophium dirhodum and Rhopalosiphum padi. We compared total parasitism rate across behavioral and physiological variation in a non-choice test. Next, we addressed total parasitism in two phases to examine: (1) the response of parasitoids to different hosts through the behavioral sequence from antennation through oviposition, and (2) the physiological suitability of different hosts for oviposition and larval development. Parasitization typically involved the following behavioral steps: (1) antennal contact, (2) abdominal bending, and (3) ovipositor insertion (acceptance). A. rhopalosiphi had the same number of antennal contacts with the three aphids but showed fewer instances of abdominal bending towards R. padi. Pre-contact host preference was found for A. ervi but it did not correspond to the level of acceptance. The number of antennal contacts by P. volucre corresponded to the parasitization level of the aphid species but more mummies were produced on M. dirhodum than on R. padi. These results suggest that parasitoid species that are habitat specialists react similarly to the different host species present in the same habitat, whereas generalist species exhibit clear preferences during host selection. Preferences were, however, not always related to host suitability.     

Scientific advances in the analysis of direct risks of weed biological control agents to nontarget plants

Research on host specificity testing protocols over the last 10 years has been considerable. Traditional experimental designs have been refined and interpretation of the results is benefiting from an improved understanding of agent behavior. The strengths, weaknesses, and best practice for the different test types are now quite clearly understood. Understanding the concept of fundamental host range (the genetically determined limits to preference and performance) and using this to maximize reliability in predicting field host specificity following release (behavioral expression of the fundamental host range under particular conditions) are still inconsistently understood or adopted despite having been identified as the critical steps in analyzing the threats posed by biological control agents to the agriculture and biodiversity of novel environments. This needs to be consistently understood and applied so the process of testing can follow a recognized process of risk analysis from hazard identification (identifying life stages of the agent that pose a threat and defining their fundamental host range) to uncertainty analysis based on the magnitude (predicted field host specificity following release) and likelihood of threats (predicted actual damage and impact) to nontargets. Modern molecular techniques are answering questions associated with subspecific variation in biological control agents with respect to host use and the chance of host shifts of agents following release. Guidelines for assessment of nontarget impacts need to recognize and adopt such recent developments and emphasize a general increased understanding of the evolution of host choice and the phylogenetic constraints to shifts in host use. This review covers all these recent advances for the first time in one document, highlighting how inconsistent interpretation by biological control practitioners can be avoided.     

Inheritance of phenotypic traits in the progeny of a Ceratocystis interspecific cross

Ceratocystis fimbriata is a fungal plant pathogen that causes black rot on Ipomoea batatas. Based on inoculation studies on numerous tree species, the pathogen is known to be host specific. The closely related species, Ceratocystis manginecans, causes severe wilt on a broad range of tree hosts, including Mangifera indica, Acacia mangium and other leguminous tree species. The genetic factors underlying the pathogenicity and host specificity of Ceratocystis species have rarely been investigated. In this study, an F₁ population of 70 recombinant progeny from a cross between C. fimbriata and C. manginecans was generated and the inheritance of various phenotypic traits was investigated. Results showed that colony colour, growth rate, asexual spore production and aggressiveness to I. batatas and A. mangium are all quantitative traits with high levels of heritability. However, conidia production and aggressiveness appeared to be regulated by a small number of genes. No correlation could be found between aggressiveness and other phenotypic traits, suggesting that these are inherited independently. This is the first study to consider genetic inheritance of pathogenicity and host specificity in Ceratocystis species and the results will contribute, in future, to the identification of quantitative trait loci and candidate genes associated with the traits investigated.     

Wisconsin desmids. II. Aufwuchs and plankton communities of selected soft water lakes,hard water lakes and calcareous spring ponds

This report summarizes the results of summer studies of five soft water lakes, five hard water lakes and six calcareous spring ponds in Wisconsin with respect to the composition of the plankton and aufwuchs communities and the relative role of desmids in those communities. The results are compared with similar data obtained from selected acid bog lakes, alkaline bog lakes and closed bogs. Soft water lakes harbored a greater aufwuchs and plankton desmid diversity than hard water lakes or spring ponds; however, diversity in acid bog lakes was substantially greater than in any other lake type. Utricularia contained the greatest desmid diversity and population density in every lake where it occurred. Staurastrum was the most prevalent genus in the plankton and it was the only one recorded from hard water lakes and calcareous spring ponds. Desmid aufwuchs population densities were roughly comparable in hard water lakes, soft water lakes and acid bogs and the contribution of desmids to the total aufwuchs population was similar for the latter two lake types. However, the plankton of acid bog lakes generally harbored substantially greater desmid populations and these populations contributed much more to the total population than in any other lake type. Aufwuchs data are presented for several hosts and comparisons of population densities are given among hosts within a given lake and between the same host in different lakes of a given type. Data for other algal groups are also included.     

Genomic regions of pufferfishes responsible for host specificity of a monogenean parasite, Heterobothrium okamotoi

The genetic mechanisms underlying host specificity of parasitic infections are largely unknown. After hatching, the larvae of the monogenean parasite, Heterobothrium okamotoi, attach to the gill filaments of hosts and the post-larval worms develop there by consuming nutrients from the host. The susceptibility to H. okamotoi infection differs markedly among fish species. While this parasite can grow on tiger pufferfish (also called fugu), Takifugu rubripes, it appears to be rejected by a close congener, grass pufferfish, Takifugu niphobles, after initial attachment to the gills. To determine the genetic architecture of the pufferfish responsible for this host specificity, we performed genome-wide quantitative trait loci analysis. We raised second generation (F₂) hybrids of the two pufferfish species and experimentally infected them with the monogenean in vivo. To assess possible differences in host mechanisms between early and later periods of infection, we sampled fish three h and 21 days after exposure. Genome scanning of fish from the 3 h infection trial revealed suggestive quantitative trait loci on linkage groups 2 and 14, which affected the number of parasites on the gill. However, analysis of fish 21 days p.i. detected a significant quantitative trait locus on linkage group 9 and three other suggestive quantitative trait loci on linkage groups 7, 18 and 22. These results indicated the polygenic nature of the host mechanisms involved in the infection/rejection of H. okamotoi. Moreover the analyses suggested that host factors may play a more important role during the growth period of the parasite than during initial host recognition at the time of attachment. Within the 95% confidence interval of the linkage group 9 quantitative trait locus in the fugu genome, there were 214 annotated protein-coding genes, including immunity-related genes such as Irak4, Muc2 and Muc5ac.     

单殖吸虫的生态学

单殖吸虫是一类宿主专一性较强的寄生虫,外环境和宿主特征对单殖吸虫有明显的影响。本文对目前单殖吸虫生态学方面的研究作了一个概述,主要论述了宿主、环境等对单殖吸虫的影响、单殖吸虫之间的关系以及单殖吸虫种群的空间分布。