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。     

化学通讯在松材线虫侵染和扩散中的作用

松材线虫为外来入侵种 ,由其引起的松材线虫病正在我国迅速扩散蔓延 ,造成我国部分地区松林资源的毁灭性破坏。松材线虫病的发生和流行与媒介天牛、寄主植物、共生真菌和细菌密切相关 ,松材线虫 -墨天牛 -松树 -共生微生物之间存在着广泛的化学联系 ,它们通过化学互作 ,调控松材线虫的行为 ,影响松材线虫的侵染和扩散     

湖北宜昌松林景观格局对松材线虫流行及扩散的影响

景观格局对能量流、物质流和物种流等生态学过程影响显著。为了探究区域生境差异对病虫害发生及扩散的影响,以湖北省宜昌市夷陵区松材线虫病为对象,结合区域森林资源二类清查矢量数据和松材线虫病普查资料,运用景观生态学的原理和方法,探究景观格局对松材线虫病发生的影响。研究结果表明:1)松林景观类型百分比、平均斑块面积、自然连接度和聚合度与松材线虫病的发病率成正相关;2)松林斑块的粒级结构分析表明,中、小斑块能抑制松材线虫病的发生,巨斑块、超大斑块对松材线虫的发生有利;3)从景观干扰上分析显示人类活动强度与松材线虫病发病率成正相关;4)在景观尺度水平上,景观的破碎度大、多样性指数高、蔓延度指数小、斑块形状简单、受人类活动影响大的乡镇松材线虫病发病率高。通过斑块类型尺度和景观尺度两个水平上的分析可知,在夷陵区乡镇尺度上,由小斑块松林组成且斑块聚集度低、景观破碎化程度低的景观格局对松材线虫病有一定的抑制作用。研究结论对当地松材线虫病的防治就有较好的参考价值。     

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。     

松材线虫的天然毒素研究进展

概述了松材线虫病的现行防治措施及存在问题,介绍了植物源和真菌源天然毒素毒杀松材线虫的研究现状及研究中遇到的问题,指出天然毒素在未来松材线虫病生物防治中的研究方向。     

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。     

Fast R-CNN深度学习和无人机遥感相结合在松材线虫病监测中的初步应用研究

松材线虫病因其破坏性强、传播速度快和防治难度大等特点,严重威胁着我国的松林资源.及时发现、定位和清理病死松树是控制松材线虫病蔓延的有效手段.本研究利用小型无人机获得松材线虫病疫点的可见光和多光谱的航摄影像.根据松树针叶颜色变化,将松材线虫Bursaphelenchus xylophilus侵染的松树分为病树和枯死树两种类型.将无人机遥感正摄影像图切割成瓦片图,根据不同植被指数的特征差异,筛选出含病树和枯死树的瓦片图.训练Fast R-CNN深度学习框架形成最终模型,通过模型运算获得病枯死松树的分布地图及坐标点位置.研究结果显示Fast R-CNN深度学习和无人机遥感相结合能有效识别出病树和枯死树,正确率分别达到90％和82％,漏检率分别为23％和34％,可为大面积监测松材线虫病的发生现状和流行动态、评估防控效果和灾害损失提供技术支撑.     

松材线虫病发生及防控现状

松材线虫在20世纪30年代就由美国的Steiner和Buhrer作为新种报道,但直至1971年才在日本被确认是引起松树枯死的原因。目前松材线虫在世界上分布还不很普遍,但对世界松林构成严重威胁。本文介绍了松材线虫发生及防控现状,着重介绍了松材线虫在世界的分布、寄主植物、传媒昆虫及管理现状。针对我国松材线虫病的发生和防控现状,探讨了我国松材线虫病防控对策和提出展望。     

松材线虫对其携带的细菌繁殖的影响

1.引言松材线虫病（Bursaphelenchus xylophilus）是松树的一种毁灭性病害,在日本、中国、韩国和北美、尼日利亚和葡萄牙等国家蔓延,造成了巨大经济损失,其中以日本和中国受害最重.一直认为松材线虫是引起该病的唯一病原,但近十几年来的研究发现,细菌在致病过程中可能起着重要作用,相继从病木和松材线虫体上分离到能对黑松苗有致萎活性的细菌.赵博光等首次根据实验提出松材线虫病是线虫和细菌共同侵染引起的复合侵染病害的假说,并在以后的试验中得到了验证.关于松材线虫对其细菌繁殖的影响研究鲜有报道.本试验采用从感病松树上分离并鉴定了的细菌菌株中选取假单胞属7株、其它属的细菌菌株3株,     

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。     

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.     

Impact of Pinewood Nematode in North America: Present and Future

Bursaphelenchus xylophilus, pinewood nematode (PWN), is the most serious pest of pine forests in Japan, but in North America its role in pine wilt disease is still being studied. The PWN is known to infest many species of Pinus, with P. nigra, P. sylvestris, and P. thunbergii the most susceptible in the eastern United States. Because of its potential, several European countries (Finland, Norway, and Sweden) and Korea have established embargoes against the importation of coniferous wood from regions of the world known to be infested with the PWN. Although the PWN is not considered an economic pest in North American forests, the recent embargoes have established an impact on current forest management practices and an economic impact on North American export trade.     

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.     

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.     

Post-inoculation Population Dynamics of Bursaphelenchus xylophilus and Associated Bacteria in Pine Wilt Disease on Pinus thunbergii

Population dynamics of the pine wood nematode Bursaphelenchus xylophilus (PWN) and its accompanying bacteria in non-inoculated twigs along with the process of the disease was observed in Japanese black pine, Pinus thunbergii inoculated with PWN. In the non-inoculated twigs, bacteria could be detected when only a few pine needles became yellow. Once most needles had turned yellow or brown, the nematode began to appear and the bacterial populations increased. At the late stages of the disease when the inoculated pine was dying and the needles were totally wilted, the populations of both nematode and bacteria started to increase rapidly. Only a few bacterial species were found at the early stages. As the disease process advanced, the bacterial populations increased rapidly in both population size and variety of the species. However, Pseudomonas fluorescens , P. sp., Pantoea sp. and Sphimgomenas pancimobilis, remained dominant.     

First report of the invasive Australian tortoise beetle Trachymela sloanei (Coleoptera: Chrysomelidae: Chrysomelinae) in Asia

The Australian tortoise beetle Trachymela sloanei (Coleoptera: Chrysomelidae: Chrysomelinae), an invasive pest of several species of Eucalyptus has been reported for the first time in Asia. It was first detected in Shenzhen, China where it has become established. Currently, T. sloanei is not a destructive forest pest in Shenzhen. Pupae and adults were frequently found infected by an unknown fungus.