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...     

重寄生属植物及其寄主的地理分布

通过对重寄生属植物及其寄主的地理分布状况的讨论,对重寄生属植物可能的起源时间、地点与迁 移进行了分析。重寄生属植物主要寄生在桑寄生科(Loranthaceae)植物上,重寄生属植物的分布区与其寄主 的基本一致,均主要分布在东南亚和中国南部的热带与亚热带地区;重寄生属植物可能起源于第三纪之前某 一时期的华南热带地区,随后向周边地区扩散。在第三纪,重寄生属植物的祖先偶然寄生在桑寄生科某些寄 生植物祖先上,经过几千万年的协同进化,形成了今天比较稳定的寄生与寄主关系。     

Host-mediated effects on the reproductive phenological asynchrony of a generalist mistletoe in China

一种泛性桑寄生植物繁殖物候异步性的寄主介导效应 寄主介导效应被认为会导致半寄生性的桑寄生植物的繁殖物候异步性，并由此为与桑寄生植物互惠共生的传粉者和种子散布者提供更长时间的食物资源供应，但目前关于此方面的研究还缺乏相关的实证数据。本研究以广泛分布于中国西南西双版纳地区的一种泛性桑寄生科植物五蕊寄生(Dendrophthoe pentandra)为材料，每周监测其开花、结果物候，检测了其开花和结果物候是否呈季节性格局，量化了五蕊寄生繁殖物候的异步程度，并检测了影响该植物始花期早晚的因素。最后，本研究还检验了五蕊寄生繁殖物候的异步性随寄主种类数量变化的效应。研究结果表明：(i)在连续两年的物候观测中五蕊寄 生的花期和果期都呈单峰分布格局；(ii)始花期显著受到植物大小和光照强度的影响，即冠幅越大和受光程度越高的植物个体有更早的始花期和更长的花期和果期；(iii)不同的寄主种类对五蕊寄生的繁殖物候有显著的影响，但与假设相反的是，随着寄主种类数量的增加，五蕊寄生繁殖物候的异步性没有显著提高。这项研究表明，在解释泛性桑寄生植物的繁殖物候异步性及寄主种类的数量对其影响的生态学意义还需进行更深入的探究。     

西双版纳桑寄生科植物的调查

西双版纳的桑寄生科植物,已发现9属24种3变种,其中有些种类在全州坝区至高海拔山区均有分布,一些种类只分布在某地区或某山关。海拔1000—1500米的山区分布的种类最多。这些桑寄生植物共有寄主树种83科263属483种。桑寄生植物在光照强、空旷的环境,种类和种群量多,在群落中寄生的层次和寄主树上寄生的部位低;在郁闭、阴湿的森林内种类种群量少,且多寄生在上层乔木的小枝上。对环境和树木适应性强的种类,其寄主可达数十个科数百种;适应性弱的种类寄主很少,甚至专类或专一的寄主。重复寄生较多,它们之间有多种复杂的关系。     

北桑寄生种群的分布格局及其寄生特性

北桑寄生(Loranthus tanakae)是桑寄生科桑寄生属的落叶灌木,多以壳斗科植物为寄主。辽东栎(Quercus wutaishanica)是黄土高原主要的优势种和建群种,也是北桑寄生的主要寄主植物。本研究调查了寄主植物辽东栎和寄生植物北桑寄生的生长状况、北桑寄生和辽东栎的空间分布格局、北桑寄生的寄生行为偏好。结果显示:(1)在调查的851株辽东栎个体中有358株(占总辽东栎个体的42.1%)被感染,共调查1112个北桑寄生个体,每株辽东栎上感染的北桑寄生个数范围为1~20个。(2)辽东栎在0~60 m尺度上呈聚集分布,在≥60 m尺度上呈随机分布;北桑寄生在0~100 m尺度上均呈聚集分布。(3)有964个北桑寄生个体生长在辽东栎上端1/2高度内,北桑寄生吸根周长大小与其寄主枝的周长呈极显著正相关(r=0.713,P0.01)。较高和较大的辽东栎个体更容易被感染,北桑寄生倾向于寄生在寄主辽东栎个体更高的位置上。     

西双版纳桑寄生植物的危害调查

西双版纳的27种桑寄生科植物,危害着野生和栽培的双子叶植物及裸子植物83科263属183种。受害严重的果园植株受害率达76—96％,老式茶园的普洱茶60％以上植株受害,三叶橡胶树50％以上受害,行道庭园树及外引载培植物也受到严重威胁,赞成经济上的重大损失。桑寄生植物的危害性与其生物学特性、对环境和树木的适应性及寄生方式有关。树木有抗寄生性,抗性强的树种少感染或不感染寄生,抗性弱的树种感染多种寄生。桑寄生的幼苗吸器不能侵入光滑、坚硬且具腊质的树皮;树皮产生隔离层除去幼苗及树体内的化学抑制作用,致使桑寄生幼苗不能正常生长发育而完成生命周期。     

大豆蚜在寄主与非寄主植物上的口针刺吸行为

用EPG记录法记录了大豆蚜Aphis glycines Matsunra在寄主和非寄主植物上的口针刺吸行为。结果表明,大豆蚜在寄主大豆植物的韧皮部取食时间长,而在非寄主棉花、黄瓜和丝瓜植物韧皮部取食时间甚短或根本未取食;非寄主植物内部对大豆蚜的侵害存在抗性,影响取食的因素和其所在部位因非寄主植物种类的不同而不同。     

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。     

几种非豆科植物根瘤内生菌侵染特征的研究

自不同科、属、种的非豆科植物根瘤分离内生菌,对其寄主植物进行了交叉侵染,结果表明,这些Frankia菌对不同寄主的侵染没有明显的专一性,供试菌可以进行跨越科、属、种的侵染,但有的菌株对于某些植物的侵染,可能存在一些特殊情况,相同菌株对不同植物的侵染能力,以及不同菌株对同一寄主的侵染能力是有差异的。从同一种植物根瘤中分离的不同菌株,侵染能力也有高低之分,供试菌随寄主植物的改变,侵染能力及所建立的共生系统固氮活性有所降低,侵染原寄主植物所形成的根瘤固氮活性较高的菌株,在改变寄主后所形成的根瘤固氮活性也比较高,在一定条件下,寄主植物的结瘤量与根瘤固氮活性呈正相关,而侵染不同寄主后,根瘤中菌体孢子的表面结构也发生了一定变化。     

青岛崂山的重寄生菌白粉寄生孢及其寄主多样性

2005-2007年从青岛崂山的16科30属35种植物上采集了143份白粉菌样品,经形态鉴定分属于7属22种。其中40份样品中检测到白粉寄生孢Ampelomyces quisqualis,其寄主植物属于8科14属15种,其寄主真菌属于7属10种白粉菌。统计分析发现,多孢穆氏节丝壳上白粉寄生孢的发生率和重寄生强度均为最高;群落组成分析发现,棕丝单囊壳为白粉寄生孢寄主真菌中的优势种,其重要值为89.22%;菊科为白粉寄生孢寄主植物中的优势科,其重要值为97.85%。     

A Host Creates an Enemy‐free Space for Mistletoes by Reducing Seed Predation Caused by a Woodboring Beetle: A Hypothesis

Parasitic plants rely on host plants for nutrition. The number of host species varies largely between groups, from single species or genus to hundreds of species. Relative abundance of the host and evolutionary history are the main requisites for parasitic plants to develop specificity to abundant hosts. In the present study, we suggest a novel mechanism by which a hemiparasitic mistletoe can develop local specificity mediated by its host. First, we describe a novel interaction in which a woodboring beetle (Hypothenemus obscurus) preys on mistletoe seeds (Psittacanthus plagiophyllus) attached to tree branches. This beetle preys more frequently on seeds deposited on branches of non‐host species than on branches of its unique local host species (53 percent on average vs. 26 percent respectively). We hypothesize that local host specificity for this mistletoe could be partly mediated by beetle‐host incompatibility, since the host offers a predation‐free space in which mistletoes have better chances to grow. Furthermore, that the exceptional gum exudates produced by this unique host species minimize beetle attacks on branches, thus reducing predation of mistletoe seeds. This novel tritrophic interaction opens an avenue for research on macroscopic host‐specificity mechanisms that occur at the level of the host bark and that have been poorly studied by plant ecologists.     

Host specificity of a Brazilian mistletoe, Struthanthus aff. polyanthus (Loranthaceae), in cerrado tropical savanna

The aim of this study was to determine if the mistletoe Struthanthus aff. polyanthus shows host specificity, and if host abundance and twig architecture influence this specificity in Cerrado (senso strictu). An area of 1.3 ha of natural savanna was sampled for the occurrence of the mistletoe. The twigs of the hosts were classified as vertical or horizontal, and the bark as smooth or rough. We sampled a total of 666 trees in the study site and 118 individuals (17.7%) hosted S. aff. polyanthus. The abundance of mistletoe was significantly affected by the bark type, but not by the twigs inclination. In the cerrado, S. aff. polyanthus seems to be a generalist, with a tendency to be more common on some hosts (Kielmeyera coriacea, Pouteria ramiflora and Styrax ferrugineus), prefering that with rough bark type.     

Host specific variation in photosynthesis of an obligate xylem‐tapping mistletoe Dendrophthoe curvata in a Bornean heath forest

Most mistletoe–host ecophysiological studies have paid attention to the influence of parasites on host performance. This paper explored the impact of varying hosts on the photosynthesis of a single mistletoe species. Here, we studied an obligate xylem‐tapping tropical mistletoe (Dendrophthoe curvata (Blume) Miquel) parasitizing four different hosts (Acacia auriculiformis A. Cunn. Ex Benth, Andira inermis (W. Wright) DC., Mangifera indica L. and Vitex pinnata L.) in a homo geneous tropical heath forest patch in Brunei Darussalam. We compared photosynthetic capacity and photosynthesis‐related characteristics of the mistletoe on four different hosts to evaluate the overall impact of hosts on the parasite. Results showed that the mistletoe–host patterns of CO₂ assimilation rates, transpiration rates and water use efficiency varied significantly based on the host. In the D. curvata–Vitex pinnata association, the mistletoe exhibited significantly lower CO₂ assimilation rates but showed no significant variations in transpiration rates and water use efficiency when compared to the host. In D. curvata–Andira inermis and D. curvata–Mangifera indica associations, the mistletoe showed significantly higher photosynthetic rates than the hosts, whereas in the D. curvata–Acacia auriculiformis association, there was no significant difference in photosynthetic rates between the counterparts. Host specificity also significantly influenced some mistletoe photosynthetic parameters such as light saturated photosynthesis, specific leaf area, leaf chlorophyll content, CO₂ assimilation rates, stomatal conductance, transpiration rates and water use efficiency. Different tree hosts intrinsically offer different resources to their obligate mistletoe parasites based on their physiology and environmental parameters. We argue that host‐specific responses have driven these intra‐specific variations in mistletoe physiology. This study provides background for future investigation on potential host‐regulated mechanisms that drive functional changes in host‐dependent mistletoes.     

元江干热河谷木质藤本的多样性及其与宿主树木的关系

木质藤本是森林生态系统的重要组分。本研究在元江干热河谷地区随机设置了30个20 m×20 m的样方,调查样方中胸径≥0.5 cm的木质藤本多样性及其与宿主树木之间的关系。结果显示:30个样方中记录到胸径≥0.5 cm的木质藤本植物共945株(隶属于22种20属11科),其中,豆科木质藤本的丰富度和多度最高;胸径≤2 cm的木质藤本占个体总数的63.7%;茎缠绕类木质藤本的个体数最多。样方中胸径≥5 cm的树木共有1060株(隶属于38种31属16科),36.0%的树木上至少附藤1株。不同径级和不同树皮粗糙度的树木被木质藤本侵扰的百分比之间存在极显著差异(P0.001)。随着宿主树木平均枝下高的增加,附藤率呈下降趋势。76.5%的木质藤本选择离其根生长点最近的树木进行攀援。表明元江干热河谷中的木质藤本以小径级占优势,树木胸径、枝下高、树皮粗糙度和木质藤本根生长点到树木的距离是影响木质藤本侵扰树木的重要因素,支持木质藤本对宿主树木的侵扰具有选择性的假说。研究结果对中国西南干热河谷退化植被的恢复与物种多样性保护具有重要意义。     

Host effects on ectomycorrhizal fungal communities: insight from eight host species in mixed conifer-broadleaf forests

To advance our understanding of host effects on the community structure of ectomycorrhizal fungi (EMF), EMF communities were compared among different host species, genera and families in two mixed conifer-broadleaf forests in Japan. Using molecular identification methods we examined EMF root tips of eight coexisting species belonging to six genera (three families): Abies and Tsuga (Pinaceae), Betula and Carpinus (Betulaceae) and Fagus and Quercus (Fagaceae). In total, 205 EMF species were detected, and the total richness was estimated to exceed 300 species using major estimators. Of the 55 EMF species occurring three or more times, eight showed significantly biased host preference. A Mantel test showed a significantly negative correlation between EMF community similarity and host taxonomic distance. Detrended correspondence analysis separated EMF communities mainly by host taxonomic and successional status. Thus, EMF communities are similar on hosts with similar taxonomic and successional status. A significant proportion of EMF exhibited host specificity, which may contribute to the extremely diverse EMF community in conifer-broadleaf forests.     

Mistletoe species richness patterns are influenced more by host geographic range than nitrogen content

Mistletoes are hemiparasites that access water and nutrients from their hosts. Previous studies have suggested that host genera with high nitrogen are parasitized by more mistletoe species but these studies failed to take into account phylogenetic relationships among host genera. Our main question was whether more mistletoe species parasitize host genera with high nitrogen content when phylogenetic relationships were controlled. We also asked whether patterns in mistletoe parasitism were related to host geographic range size, host fruit type and host spinescence. Overall, we found no difference between conventional and phylogenetically controlled analyses. We also found no evidence for higher mistletoe species richness on host genera with high nitrogen, fleshy fruits or spinescence. However, similar to findings for animal parasites, we found that host genera with large geographic range had higher mistletoe species richness. This is likely because a greater number of mistletoe species will encounter hosts that have a greater geographic distribution. Mistletoe studies frequently assume that nitrogen status drives patterns in mistletoe parasitism but our study suggests that macroecological patterns in mistletoe assemblages are primarily determined by host geographic range.     

Hymenopterous parasitoids of bark beetles [Scolytidae] in Israel: Host relation,host plant,abundance and seasonal history

Twenty six species of parasitoids were recorded from 15 species of bark beetles in Israel. Parasitoids were collected from infested cut branches of broadleaves and trap-trees of pine and cypress. Most of the parasitoids are oligophagous and range fromEcphylus caudatus, a monophagous species exclusive toHypoborus ficus, toHeydenia pretiosa, which develops on 11 species.Scleroderma domesticus, Agrilocida ferrieri andEupelmus nearurozonus are occasional parasitoids of bark beetles.Cephalonomia hypobori, Israelius carthami, S. domesticus, Entedon ergias, Cerocephala eccoptogasteri andRoptocerus xylophagorum are cryptoparasitoids and search for their host in the galleries. Known parasitoids are listed from 15 tree genera belonging to 8 botanical families. A typical range for the common parasitoids is presented with within-tree distribution of pine parasitoids. Relatively monophagous species are usually dominant parasitoids in a specific beetle population, whereas relatively polyphagous parasitoids vary in abundance among different host populations.Calosota spp., 2Eurytoma spp. andDendrosoter hartigii are usually present in small numbers. Information concerning the seasonal history of the parasitoids suggests that the major species may raise about 5 to 7 annual generations. Contribution from the Agricultural Research Organization, Bet Dagan, Israel N^o 1331-E, 1984 series     

Macroscale analysis of mistletoe host ranges in the Andean‐Patagonian forest

• The number of host species infected by a mistletoe (host range) is critical in that it influences prevalence, virulence and overall distribution of the parasite; however, macroecological analyses of this life history feature are lacking for many regions.
• The Andean‐Patagonian forest, found along the southern Andes from 35 °S to Tierra del Fuego at 55 °S, contains 12 mistletoe species in three families (Loranthaceae, Misodendraceae and Santalaceae). By tabulating herbarium records, the host ranges and geographical distributions of these mistletoes were explored.
• Our results show that these parasites occur on 43 plant species in 24 families but with varying degrees of specificity. All Misodendrum species and Desmaria mutabilis (Loranthaceae) are specialists that use Nothofagus as their primary hosts. Tristerix and Notanthera (Loranthaceae) and Antidaphne and Lepidoceras (Santalaceae) are generalists parasitizing more than six host species from several genera and families. Although many of the mistletoe species are sympatric, there is low overlap in host use.
• Our data show that in the southern South American bioregion, generalist mistletoes have smaller geographic ranges than specialists. This contrast with a previous hypothesis that predicted mistletoes with large geographic ranges would also have large host ranges, and conversely, less diverse regions would have more specialised mistletoes.

     

Are patterns in the taxonomic,biological and ecological traits of water beetles congruent in Mediterranean ecosystems?

1. Coleoptera species show considerable diversity in life histories and ecological strategies, which makes possible their wide distribution in freshwater habitats, including highly stressed ones such as saline or temporary waterbodies. Explaining how particular combinations of traits allow species to occupy distinctive habitats is a central question in ecology. 2. A total of 212 sites, sampled over a wide range of inland aquatic habitats in the south‐eastern Iberian Peninsula, yielded 272 species belonging to 68 genera and 11 families. The affinities of genera for 11 biological and 11 ecological traits, gathered from literature and the authors’ own expertise, were used to assess the degree of congruence between taxonomic, biological and ecological traits. 3. Taxonomic richness was significantly related to the number of both biological and ecological trait categories, with the richest families also showing the highest functional and ecological diversity. A fuzzy correspondence analysis performed on the abundance‐weighed array of biological traits separated genera according to categories of diet, feeding habits, respiration, reproduction and locomotion. A similar analysis of ecological traits revealed that preferences related to longitudinal distribution (headwater to mouth), local habitat and current velocity best discriminated genera. At the family level, there was a distinctive functional grouping of genera based on biological traits. Only Elmidae showed noticeable homogeneity across genera for both biological and ecological traits. 4. Co‐inertia analysis demonstrated a significant match between biological and ecological traits (Rv‐correlation = 0.35, P < 0.001). Elmidae genera displayed the highest concordance, whereas Hydraenidae demonstrated the lowest. 5. These results indicate that the predominance of habitat filtering processes in headwater streams yields biological trait conservatism (as shown by Elmidae genera), as well as trait convergence for some specific traits (for instance, respiration) among certain Dytiscidae genera and other typical rheophilic taxa, whereas other biotic factors, such as competition among species, appear more prominent in less stressed habitats. Further knowledge of traits, especially regarding physiological capabilities, is needed to better understand water beetle life history strategies.