松材线虫及其传媒松墨天牛的监测和防治现状

松材线虫起源于北美大陆。1 982年侵入中国。松材线虫能引起一种林业上最具危险性、毁灭性的病害“松材线虫病”。松材线虫病的病因复杂,传播途径多样,不同国家地区对其采取的监测和防治策略也有所差异。目前,该病局限分布于北美和东北亚,但在世界范围内其扩散趋势日益明显。该文简要从监测预警,物理、化学、生物等防治方法、以及监测防治中存在问题和发展趋势等方面概述了国内外松材线虫Bursaphelenchusxylophilus及其关键传媒松墨天牛MonochamusalternatusHope的研究现状,对制定适宜我国的松材线虫病监测和防治策略有借鉴和参考价值。     

温度对松褐天牛传递松材线虫数量的影响

松材线虫病是一种重要的检疫性病害,松褐天牛是传播松材线虫的主要媒介昆虫.本实验研究了温度对松褐天牛传递松材线虫数量的影响.设置22℃、28℃和34℃ 3个温度梯度,结果表明松褐天牛成虫的寿命随温度升高而缩短,其中雌虫寿命短于雄虫,且羽化进度不太一致,多数松褐天牛携带的松材线虫量在1000～9999条之间.通过对松褐天牛取食传入松枝的松材线虫量的追踪记录发现,随着温度升高,传播线虫的高峰时段随之提前.34℃高温下松褐天牛的传递率最低,表明高温对松材线虫病的发生具有抑制作用.     

松材线虫及其关键传媒墨天牛的研究进展

松材线虫Bursaphelenchusxylophilus (Steiner&Buhere,1 93 4Nickle,1 981 )是一种世界多国公认的重大外来生物。其原产地在美国 ,但松材线虫并不严重危害该国松林 ;日本受害最重 ,经过几十年的研究与防治 ,现已基本能控制松材线虫病大发生。自 1 982年我国南京中山陵首次发现松材线虫以来 ,其在我国的扩散趋势越来越明显 ,现已成为我国一种重要入侵病原生物。它不但对我国南方数百万公顷松林构成毁灭性威胁 ,影响我国经济和社会可持续发展 ,而且将破坏我国一些著名风景名胜区、文化遗产地。同时 ,松材线虫正成为一项技术壁垒 ,严重影响我国的进出口贸易。该文简要从松材线虫及其关键传煤墨天牛Monochamusspp .的生物学特性、分布状况 ,松材线虫病的蔓延条件及影响因素等方面概述国内外的研究动态 ,以期为我国对松材线虫的研究与防治工作提供参考     

松材线虫对媒介天牛和寄主松树化学信息信号的识别与利用

当环境恶化时繁殖型线虫可以改变自身发育模式进入扩散周期,并利用环境化学信息准确寻找适宜生存的健康寄主或食物,进行短距离迁移。伞滑刃属植物寄生线虫的扩散迁移需要借助媒介昆虫的携带。松材线虫在松树死亡后就会形成分散型3龄线虫,并准确定位墨天牛属老熟幼虫,90％以上聚集于蛹室周围,形成“蛹室效应”,并被天牛携带到新寄主,1头天牛有时可携带上万条松材线虫。中国科学院动物研究所森林害虫化学生态组最新研究揭示了松材线虫扩散迁移的化学信息机制：线虫如同昆虫一样可以辨别信息混合物比例。     

松墨天牛化学生态学

松墨天牛(Monoohamus alternatus)是危害针叶树的重要蛀干害虫,而且是松材线虫病(Bursaphelenchus xylophilus)的主要传播媒介昆虫.本文综述了松墨天牛与寄主植物之间、松墨天牛种内及松墨天牛与松材线虫之间的化学生态学研究进展.在松墨天牛与寄主植物相互关系中,寄主植物中的萜烯类挥发物在松墨天牛选择取食和产卵寄主时发挥重要的调节作用,这些挥发物常常因寄主危害与否而发生改变,并对天牛表现出性别差异;寄主中的化学物质如碳水化合物、氨基酸、甾醇、磷脂和黄酮等能够刺激或驱避天牛的取食和产卵行为.松墨天牛种内通讯过程中,两性天牛的吸引、求爱和交尾等生殖行为由性信息素所引起;雌天牛分泌的产卵忌避信息素能够调节产卵刻槽的空间分布,有助于卵的分散,避免下一代幼虫对生存空间和食物的竞争.松墨天牛与松材线虫之间化学生态关系的物质基础为寄主植物、天牛及线虫产生的单萜、CO2及不饱和脂肪酸,它们调控线虫向蛹室的聚集、进入虫体和脱离虫体等行为.最后,展望了松墨天牛化学生态学的研究方向.     

辽宁抚顺松材线虫入侵松林内天牛种类调查

【目的】松材线虫Bursaphelenchus xylophilus (Steiner&Buhrer) Nickle的媒介昆虫云杉花墨天牛Monochamus saltuarius Gebler在辽宁省被发现意味着我国北方松林的生态安全正在遭受严重的威胁。明确松材线虫入侵松林内的天牛种类、数目,可以为早期监测松材线虫媒介昆虫和潜在媒介昆虫的种群动态以及预测松材线虫病的发生提供参考。【方法】为了明确天牛广谱型引诱剂、APFI持久增强型松墨天牛高效诱剂、F8型松墨天牛引诱剂及其复配诱芯的诱捕效果,于2019-2020年的5-10月在辽宁省抚顺市的油松林、红松林、落叶松林开展诱捕天牛试验。【结果】将天牛广谱型引诱剂和F8型松墨天牛引诱剂放在同一诱捕器中具有较好引诱效果,每诱捕器捕获的天牛物种数量（油松林18种,红松林14种,共计19种）和天牛样本数量（油松林（18.31±8.86）头/周,红松林（23.44±10.92）头/周）最多。在试验林地共计诱捕到34种共计13307头天牛,其中云杉花墨天牛数量最多,占总诱捕量的67%,褐梗天牛Arhopalus rusticus、锯天牛Prionus insularis、小灰长角天牛Acanthocinus griseus、松皮花天牛Rhagium japonicum分别占总诱捕量的13.2%、6.6%、4.1%和2.7%。【结论】捕获到危害针叶树的天牛8种,包括云杉花墨天牛（优势种）、小灰长角天牛、灰长角天牛Acanthocinus aedilis、褐梗天牛、脊鞘幽天牛Asemum striatum和锯天牛。根据天牛的取食产卵习性推测,小灰长角天牛、灰长角天牛在补充营养的时候可能会传播松材线虫到健康松树上,而褐梗天牛、脊鞘幽天牛和锯天牛羽化成虫后不需补充营养且产卵在衰弱木的树皮缝隙或者表土处,它们有效传播松材线虫的几率较小。     

三峡库区松材线虫病扩张速度对人为活动的响应

松材线虫病是我国森林重要的检疫性病害,除自然媒介天牛传播,人为因素介导的传播在松材线虫病扩散和蔓延中起着至关重要的作用。选择在我国松材线虫病的重点发生区域三峡库区,研究马尾松林景观格局和以人为活动强度为主要因子的松材线虫病扩散规律,尝试揭示松材线虫病扩散机制。结果显示三峡库区的疫点数在近年有上升趋势,各地区发病率得到一定控制;在疫区和非疫区,马尾松林斑块聚合度最大的是非疫区的大渡口,为98.6406;斑块分离度最大的是非疫区的秭归,为0.9318;方差分析结果显示马尾松林景观格局和松材线虫病之间没有相关性。进一步研究了松材线虫病和人为活动强度的联系,结果显示松材线虫病发病率和地区路网密度、人口总量具有较强的相关性,和地区GDP、货运周转量相关性小。宜昌的松材线虫病发病率和路网密度的相关系数为0.985,和人口总数的相关系数为0.866;重庆的松材线虫病发病率和路网密度相关系数为0.924,和人口总数相关系数为0.999;其次基于路网密度和人口总数,对三峡库区松材线虫病疫情在未来十年进行了预测,结果显示随着路网密度和人口总数的扩增,宜昌松材线虫病也将呈现逐步增大的趋势,R~2值为0.919和0.637;重庆发生趋势一致,R~2值为0.976和0.992。     

丝状真菌杀松材线虫代谢产物研究进展

松材线虫病是破坏我国森林生态系统最为严重的病害,具有极强的传播性和破坏性,防治此种病害迫在眉睫。基于对物理和化学方式防治松材线虫的研究,对环境友好度最高的生物防治具有更广的研究前景。丝状真菌及其次级代谢产物,来源于自然,与传统的化学杀线虫药剂相比,对环境影响较小,针对松材线虫的致死作用更为专一,因此,从丝状真菌的次级代谢产物中分离获得杀松材线虫活性产物并测定其结构和活性,对于松材线虫病的防治具有重要意义。本文对丝状真菌产生的具有杀松材线虫活性产物的结构、活性展开综述,发现近二十年共有57个活性产物被发现,且结构多种多样,活性差别较大,为了更好地开展此领域的研究,本文对所有产物的结构和活性进行了系统总结,最后又对该领域的研究进行了总结和展望,以期对松材线虫病的生物防治和丝状真菌杀松材线虫次级代谢产物的深入研究提供参考。     

A-3型松褐天牛引诱剂诱虫谱研究

2002～2004年,在广州地区应用A-3型松褐天牛Monochamus alternatus Hope(鞘翅目Coleoptera天牛科Cerambycidae)引诱剂诱捕鞘翅目昆虫,结果表明:A-3型松褐天牛引诱剂具有较广的诱虫谱,可以诱捕到鞘翅目中10个科48种昆虫;松树的主要蛀干害虫是松褐天牛、赤梗天牛Arhopalus unicolor Ganhan、马尾松角胫象Shirahoshizo patruelis Voss、松瘤象Hyposipalus gigas Fabricius和松纵坑切梢小蠢Tomicus piniperda Linnaeus等小蠹虫;进一步分离所诱捕的松褐天牛及其他松树主要蛀干害虫携带松材线虫Bursaphelenchus xylophilus Nickle的情况,发现松褐天牛与赤梗天牛均携带松材线虫,其中松褐天牛是松材线虫病最重要的传播媒介.     

携带松材线虫对松墨天牛成虫肠道和气管细菌的影响

【目的】探究被松墨天牛Monochamus alternatus携带的松材线虫Bursaphelenchus xylophilus对松墨天牛肠道和气管细菌的影响。【方法】野外采集携带松材线虫的松墨天牛成虫后,取出完整肠道和气管进行细菌总DNA抽提后进行16S rDNA基因测序并拼接,并利用生物信息学方法分析松墨天牛成虫肠道和气管细菌组成、结构、丰度和多样性。【结果】携带松材线虫的松墨天牛成虫肠道和气管细菌菌群共检测到15门26纲66目110科201属296种,可操作分类单元(operational taxonomic unit, OTU)数目为444。携带松材线虫的松墨天牛成虫比未携带松材线虫的松墨天牛成虫肠道优势细菌菌群变化不显著,均为变形菌门(Proteobacteria)肠杆菌目(Enterobacterales);携带松材线虫的松墨天牛成虫气管优势细菌菌群为变形菌门肠杆菌目,未携带松材线虫的松墨天牛成虫气管优势细菌菌群为厚壁菌门(Firmicutes)乳杆菌目(Lactobacillales)。携带松材线虫的松墨天牛成虫较未携带松材线虫的松墨天牛成虫气管细菌多样性和丰度升高,细...     

Pathogenic cellulase assay of pine wilt disease and immunological localization

The pine wilt disease caused by Bursaphelenchus xylophilus (BX), also known as the pine wood nematode (PWN), is the most devastating disease of pine trees. In this work, a high molecular weight B. xylophilus cellulase antigen (BXCa) was purified from total homogenates of nematodes. BXCa was found to be able to hydrolyze carboxymethyl cellulose (CMC) efficiently (155.65 U/mg) and to have an approximate molecular mass of 58.9 kDa. We harvested anti-BXCa antibodies and performed immunocytochemical assays, which revealed the localization of cellulase pools in the esophageal gland cells of the PWN. It was also discovered that cellulase was secreted from the stylet and was used to hydrolyze cellulose to facilitate the PWN entering host cells. These results are consistent with other plant parasitical nematodes. Interestingly, strong fluorescence signals from cellulase staining were observed in tracheid cells in naturally infected pine wood, in addition to ray cells and the resin canal zone. These results strongly suggest that the cellulase released by the PWN is one of the pathogenic substances of pine wilt disease and is responsible for the development of the early symptoms of the disease.     

Pathogenic Cellulase Assay of Pine Wilt Disease and Immunological Localization

The pine wilt disease caused by Bursaphelenchus xylophilus (BX), also known as the pine wood nematode (PWN), is the most devastating disease of pine trees. In this work, a high molecular weight B. xylophilus cellulase antigen (BXCa) was purified from total homogenates of nematodes. BXCa was found to be able to hydrolyze carboxymethyl cellulose (CMC) efficiently (155.65 U/mg) and to have an approximate molecular mass of 58.9 kDa. We harvested anti-BXCa antibodies and performed immunocytochemical assays, which revealed the localization of cellulase pools in the esophageal gland cells of the PWN. It was also discovered that cellulase was secreted from the stylet and was used to hydrolyze cellulose to facilitate the PWN entering host cells. These results are consistent with other plant parasitical nematodes. Interestingly, strong fluorescence signals from cellulase staining were observed in tracheid cells in naturally infected pine wood, in addition to ray cells and the resin canal zone. These results strongly suggest that the cellulase released by the PWN is one of the pathogenic substances of pine wilt disease and is responsible for the development of the early symptoms of the disease.     

Using an evapo-transpiration model (ETpN) to predict the risk and expression of symptoms of pine wilt disease (PWD) across Europe

The pine wood nematode (PWN) Bursaphelenchus xylophilus is the causal agent of pine wilt disease (PWD), a xylem restricting disease of pine trees. PWN, a native of North America where it very rarely kills native pine trees, has spread internationally killing host trees in China, Japan, Korea, Taiwan and Portugal, with isolated incursions into Spain. Based on the locations where tree mortality has been recorded, it appears that pine trees growing in hot, dry conditions are more susceptible to pine wilt disease. This paper describes the ETpN model, an evapo-transpiration model (previously developed by Forest Research), which has been modified to incorporate the presence of PWN inside a tree and which predicts the regions of Europe that are likely to succumb to PWD. ETpN acts independently of the vector beetle (Monochamus spp.), predicting the likelihood of PWD on the assumption that a tree in a particular region has already been infested by the pine wood nematode. Different regions across Europe are included to investigate and demonstrate how different climates affect PWD incidence significantly. Simplified, “lite” and latency models have been developed to allow a non-specialist user to determine respectively the risk of PWD at a particular location and the likelihood of delays (latency) in expression of wilt symptoms.     

Pathogenicity of aseptic Bursaphelenchus xylophilus

Pine wilt is a disease of pine (Pinus spp.) caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus. However, the pathogenic mechanism of pine wilt disease (PWD) remains unclear. Although the PWN was thought to be the only pathogenic agent associated with this disease, a potential role for bacterial symbionts in the disease process was recently proposed. Studies have indicated that aseptic PWNs do not cause PWD in aseptic pine trees, while PWNs associated with bacteria cause wilting symptoms. To investigate the pathogenicity of the PWN and its associated bacteria, 3-month-old microcuttings derived from certain clones of Pinus densiflora Siebold & Zucc. produced in vitro were inoculated under aseptic conditions with aseptic PWNs, non-aseptic PWNs and bacteria isolated from the nematodes. Six-month-old aseptic P. densiflora microcuttings and 7-month-old P. massoniana seedlings were also inoculated under aseptic conditions with aseptic PWNs and non-aseptic PWNs. The results showed that the aseptic microcuttings and seedlings inoculated with aseptic PWNs or non-aseptic PWNs wilted, while those inoculated with bacterial isolates did not wilt. Nematodes were recovered from wilted microcuttings and seedlings inoculated with aseptic PWNs and non-aseptic PWNs, and the asepsis of nematodes recovered from aseptic PWN-inoculated microcuttings and seedlings was reconfirmed by culturing them in NB liquid medium at 30°C for more than 7 days. Taken together, the results indicate that the asepsis of PWN did not cause the loss of pathogenicity.     

松材线虫(Bursaphelenchus xylophilus)入侵对马尾松(Pinus massoniana)林分生长的影响及相关生长模型

松材线虫（Bursaphelenchus xylophilus）是一种松树上发生严重的有害生物,它不仅改变了生态系统的结构和功能,而且改变了系统内生物的原有特性和地理分布。松材线虫及其引起的松树萎蔫病已对中国马尾松林（Pinus massoniana）的树木成长产生了巨大影响。基于此,使用＂每木调查法＂和＂样方法＂,对松材线虫入侵后的马尾松林内松树的各项生长指标因子进行了调查分析,其结果表明：自松材线虫1996年入侵所调查地区的松林后,对于受害松树不管是伐倒木（被伐倒）还是倒木（自然倒地）,其对周围马尾松胸径生长的影响是显著的,而对树高生长的影响不显著。最后建立了一系列的灰色和灰色-马尔可夫链数学模型,其预测结果精度高,可用于今后受害和未受害区马尾松林分因子的生长预测。     

Host Deception: Predaceous Fungus,Esteya vermicola,Entices Pine Wood Nematode by Mimicking the Scent of Pine Tree for Nutrient

Background

A nematophagous fungus, Esteya vermicola, is recorded as the first endoparasitic fungus of pine wood nematode (PWN), Bursaphelenchus xylophilus, in last century. E. vermicola exhibited high infectivity toward PWN in the laboratory conditions and conidia spraying of this fungus on Japanese red pine, Pinus densiflora, seedlings in the field protected the pine trees from pine wilt disease to some extent, indicating that it is a potential bio-control agent against PWN. Previous research had demonstrated that the living fungal mycelia of E. vermicola continuously produced certain volatile organic compounds (VOCs), which were responsible for the PWN attraction. However, identity of these VOCs remains unknown.

Methodology/Principal Findings

In this study, we report the identification of α-pinene, β-pinene, and camphor produced by living mycelia of E. vermicola, the same volatile compounds emitted from PWN host pine tree, as the major VOCs for PWN attraction using gas chromatography-mass spectrometry (GC-MS). In addition, we also confirmed the host deception behavior of E. vermicola to PWN by using synthetic VOCs in a straightforward laboratory bioassay.

Conclusions/Significance

This research result has demonstrated that the endoparasitic nematophagous fungus, E. vermicola, mimics the scent of PWN host pine tree to entice PWN for the nutrient. The identification of the attractive VOCs emitted from the fungus E. vermicola is of significance in better understanding parasitic mechanism of the fungus and the co-evolution in the two organisms and will aid management of the pine wilt disease.     

Evolutionary change in a pine wilt system following the invasion of Japan by the pinewood nematode, <Emphasis Type="Italic">Bursaphelenchus</Emphasis><Emphasis Type="Italic">xylophilus</Emphasis>

Pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causative agent of pine wilt disease (PWD) of pine trees and is transmitted by cerambycid beetles belonging to the genus Monochamus. PWN is believed to have been introduced into Japan from North America at the beginning of the 20th century. In this article, we first provide an outline of the PWD system and the range expansion of PWN in Japan and then review the literature, focusing on the virulence of PWN. Virulence is a heritable trait in PWN, with high virulence being closely related to a high rate of reproduction and within-tree dispersal. When two PWN isolates with different virulence levels are inoculated into pine seedlings, the more virulent nematodes always dominate in dead seedlings. In a laboratory setting, many more virulent nematodes board the insect vectors than avirulent ones. The age at which vectors transmit the most abundant PWNs to pine twigs changes during the course of a PWD epidemic. However, the relation between virulence and transmission of PWN remains as yet relatively unknown. Such information would enable ecologists to predict the evolution of the PWD system. In this review we also compare ecological traits between the PWN and the avirulent congener, B. mucronatus.