季也蒙假丝酵母对松材线虫病的抑制作用

松材线虫病是重要的森林病害,该病与松材线虫携带的病原菌和松树的内生病原菌密切相关。在室内条件下,初步研究了从人工培养的松材线虫上分离到的菌株C对松材线虫病的抑制作用。在健康的水培马尾松枝上分别接种松材线虫接种液、菌株C接种液、松材线虫与菌株C的混合接种液。处理后松枝的相对重量与相对蒸腾强度均为:接种菌株C的松枝>混合接种的松枝>接种线虫的松枝。处理后15d时,接种线虫的松枝与混合接种的松枝的相对重量有显著性差异(p<0.05)。接种线虫松枝的存活期显著短于其它处理松枝的存活期(p<0.05)。接种菌株C的针叶褐变株数少于接种线虫的松枝,两者有显著性差异(p<0.05)。从接种线虫和混合接种的所有松枝中都分离到松材线虫,且分离出的线虫量没有显著性差异。将8个月生的断根马尾松苗插入菌株C的查彼培养液的滤液中培养,6d后松苗的平均感病指数和感病株率均显著少于对照(p<0.05)。这表明,菌株C对松材线虫病有抑制作用,菌株C培养液中产生的某些代谢物质有利于松苗的抗病和存活。菌株C可能抑制了松树上的内生病原菌和松材线虫携带的病原微生物,或提高了松树的生长力和抗逆能力。经电子显微镜观察并参照AP I 20 C AUX鉴定系统鉴定,菌株C为季也蒙假丝酵母C and id a gu ilierm ond ii。     

Transmission of the pine wood nematode Bursaphelenchus xylophilus through feeding activity of Monochamus galloprovincialis (Col., Cerambycidae)

Abstract:  Transmission of the pinewood nematode (PWN) Bursaphelenchus xylophilus (Steiner & Bührer) Nickle to Pinus pinaster Aiton branches through feeding wounds of its vector in Portugal, Monochamus galloprovincialis Olivier, was studied under laboratory conditions. All the B. xylophilus -infected beetles transmitted nematodes to branches they fed. The transmission was more frequent during the first 6 weeks after emergence, with transmission peaks during the second and the sixth week. The adult M. galloprovincialis transmitted nematodes for a mean of 5 weeks, independently of the beetle's sex or longevity. No relation was found between beetle feeding intensity and effective transmission of B. xylophilus to the branches. The nematode transmission ceased after the ninth week, even in insects which still had B. xylophilus on their bodies. The longevity of the nematode-free insects (control group) was slightly higher than the B. xylophilus -infected beetles, although with no significant difference. The results emphasize the necessity to control the immature stages of M. galloprovincialis prior to emergence and develop efficient strategies to capture and eliminate the recently emerged beetles, as majority of the nematode infection of healthy pine trees occurs during a short period of few weeks after beetle emergence.     

Temperature Effects on the Transmission of Bursaphelenchus xylophilus (Nemata: Aphelenchoididae) by Monochamus alternatus (Coleoptera: Cerambycidae)

The object of this research was to investigate the effects of ambient temperature on the transmission of the pinewood nematode, Bursaphelenchus xylophilus, by its vector, Monochamus alternatus. Ninety M. alternatus were reared individually at one of three constant temperatures (16, 20, and 25 °C). As the ambient temperature decreased from 25 to 16 °C, longevity of vectors decreased, nematode transmission efficiency decreased, and the peak period of nematode transmission was delayed and its peak height decreased. Low temperature may inhibit the transmission process, and this inhibition could be partially responsible for preventing pine wilt disease from devastating pine forests in cool regions.     

Population density ofMonochamus alternatus adults (Coleoptera: Cerambycidae) and incidence of pine wilt disease caused byBursaphelenchus xylophilus (Nematoda: Aphelenchoididae)

Summary The seasonal occurrence ofMonochamus alternatus and newly weakened trees were investigated in aPinus thunbergii stand for 4 years. Adult beetles were present between June and September with a peak in their population occurring in early July followed by a decline then a period of about one month being in a steady number. The average number ofBursaphelenchus xylophilus (Nematoda), which is the causal agent of pine wilt disease, within beetles decreased as the season advanced. Pine trees newly weakened byB. xylophilus appeared between June and October, especially from August to October. The proportion of weakened or killed trees was directly proportional to the average beetle density per tree from June to August.     

中国松材线虫病空间分布格局

应用地统计学和克里格插值方法,分析了松材线虫病在中国的空间分布结构和空间相关性.研究表明,松材线虫病在中国呈聚集分布.在全国和江苏、安徽、广东、浙江5个不同空间尺度下,半变异函数均为球形,空间依赖性距离分别可达10 1888°、3.4464°、2.1581°、3.08°和2.4376°.松材线虫病在中国有着2个明显的聚集分布区域,一个位于(30.5～32.5°N,117.7～120.5°E),以南京为中心,包括江苏、安徽大部和浙江西北部,另一个位于(22.5～24°N,113～114.5°E ),在广东境内.松材线虫病在中国早期空间分布自然扩散模型为R = 5.4743e0.4139t(R2 = 0.9204).     

松材线虫病发生点格局及影响因素

松材线虫病在中国大陆造成了巨大的生态与经济价值损失,南方地区尤为严重,分析松材线虫病空间分布、量化环境因素对其发生的影响对于松材线虫病的防控整治具有重要意义。本研究以江西省赣州市南康区松材线虫病为研究对象,采用核平滑密度、Ripley’s K函数、点过程模拟等空间点格局分析方法,探讨了区域松材线虫病发生的空间格局及其对环境变量的响应。结果表明: 研究区松材线虫病的发生不是随机分布,而是存在显著的空间聚集区。地形因子、植被因子和人类活动因子是影响松材线虫病空间异质性分布的主要因素。空间点格局分析表明,海拔、坡度、距最近道路距离、道路密度、距最近居民点距离、郁闭度和植被类型对松材线虫病的发生具有重要影响。在森林病害管理中,除了加强因人类活动引起病害传播源的管控外,还应该考虑地形、植被类型等特征进行松材线虫病害的综合预警监测。     

携带与未携带松材线虫的松墨天牛转录组差异表达基因分析

【目的】本研究旨在建立携带与未携带松材线虫Bursaphelenchus xylophilus的松墨天牛Monochamus alternatus成虫各组织的转录组数据库,揭示松墨天牛对松材线虫响应的转录组整体表达特征。【方法】以携带和未携带松材线虫的松墨天牛成虫的表皮、气管和脂肪体为材料,采用Illumina HiSeq^TM 2000测序平台开展转录组测序,利用Trinity软件对RNA-Seq数据进行从头组装,利用NCBI数据库进行基因注释。通过DEG-Seq分析携带和未携带松材线虫的松墨天牛成虫中的差异表达基因,对上调表达基因进行GO和KEGG代谢途径富集分析,并通过实时荧光定量PCR技术对部分差异表达的基因包括ENV, CDK1, HSP70-C, HSP70, HSP75, DUO, PABPN1和IGFP基因的表达水平进行验证。【结果】测序过滤后共获得55 059条单基因簇(unigene),平均长度为1 536 bp。将unigene与数据库中的序列进行BLASTX比对,成功注释24 354条unigenes,其中4 022条unigene在GO数据...     

Inhibitory Effect of Bursaphelenchus mucronatus (Nematoda: Aphelenchoididae) on B. xylophilus Boarding Adult Monochamus alternatus (Coleoptera: Cerambycidae)

Inhibitory effects of Bursaphelenchus mucronatus on the number of B. xylophilus carried by an adult Monochamus alternatus were investigated using artificial pupal chambers. When pupal chambers were infested with either B. xylophilus or B. mucronatus, the load of B. xylophilus onto the beetle was greater (P < 0.001) than that of B. mucronatus. However, within the pupal chamber there was no difference in the abundance of the third-stage dispersal juveniles, which would molt to the fourth-stage dispersal juveniles to board beetles. The nematode load on beetles that emerged from pupal chambers infested with both Bursaphelenchus species was smaller (P = 0.015) than that of beetles with B. xylophilus alone but greater (P < 0.001) than that of beetles with B. mucronatus alone, suggesting an inhibitory effect of B. mucronatus. As a result of this study, the rate of inhibition of B. mucronatus on molting of third-stage dispersal juveniles of B. xylophilus to fourth-stage dispersal juveniles was 0.65, which resulted in great inhibition on boarding beetles at a rate of 0.7.     

Transmission of Bursaphelenchus xylophilus through Oviposition Wounds of Monochamm carolinensis (Coleoptera: Cerambycidae)

Transmission of pinewood nematode through Monochamus carolinensis oviposition wounds was documented. Nematode transmission was measured as the average number of nematodes isolated per oviposition wound excavated and also as the percentage of oviposition wounds from which nematodes were isolated. The influence of three factors that might affect nematode transmission was investigated: age of the beetle vector, number of nematodes carried per beetle, and egg deposition in the oviposition wound. Only the number of nematodes carried by the beetle was found to have a significant effect on transmission. Nematodes were transmitted more frequently and in slightly greater numbers by beetles carrying more nematodes. The influence of pinewood on nematode exit from beetles were investigated by comparing nematode exit from beetles placed over pine chips with those placed over distilled water. Nematodes exited in greater numbers and at a higher frequency from beetles over pine chips than from beetles over distilled water. Apparently, the nematodes are able to detect a factor from the pine chips that promotes their exit from the beetles.     

松墨天牛对寄主树木的产卵选择

在室内采用选择行为方法,研究了松墨天牛Monochamus alternatus对几种松属植物的产卵选择行为。结果表明,松墨天牛对黑松Pinus thunbergii的选择性最强,对马尾松P.massoniana的选择性最弱,二者间差异显著,它们与火炬松P. taeda和湿地松P. elliottii间无明显差异。在黑松和马尾松的被松材线虫危害木与健康木之间,松墨天牛明显选择被害木产卵;具产卵痕枝段和虫粪处理过的枝段,对松墨天牛的产卵有显著抑制作用,松墨天牛明显地选择对照枝段产卵。     

松墨天牛在秦巴林区不同寄主上的危害规律

松墨天牛Monochamus alternatus是次期性蛀干害虫,也是松材线虫病的主要传播媒介,廓清该害虫在秦巴林区不同寄主上的危害程度和发生规律,对于控制松材线虫病的扩散蔓延具有重要意义.本研究对秦巴林区遭受松材线虫病严重危害的3种主要松树(油松Pinus tabuliformis、华山松P.armandii和马尾松P.massoniana)进行了冬季疫木野外解析,并在统计不同胸径、不同高度疫木树干上松墨天牛侵入孔和幼虫数量的基础上,采用聚集度指标分析方法,对该害虫在不同寄主上的危害差异进行了比较研究.结果表明,松墨天牛在3种寄主上的危害程度具有显著差异,以华山松受害最重,其次分别为马尾松和油松;越冬幼虫在油松上主要危害皮下1～2 cm的边材;在华山松和马尾松上危害比较多样,以髓心部位受害最重,其后依次为心材、边材和树皮;在油松和华山松上,松墨天牛主要在树干7m以下部分危害,而在马尾松上主要危害树干7m以上部分,且虫口数量均与寄主胸径呈显著正相关.松墨天牛侵入孔和越冬幼虫在不同寄主树干上均呈聚集性分布.本研究揭示了松墨天牛在秦巴林区3种主要寄主上的危害规律,对于进一步开展大尺度地理范围松墨天牛的寄主选择性及危害规律研究提供了基础信息,也为秦巴林区松墨天牛的有效防治和松材线虫病的蔓延控制提供了新的重要信息.     

不同干扰措施对松材线虫入侵松林内物种多样性的影响

经野外调查发现:松材线虫入侵松林后,对原先林型相同的两块染病松林而言,经过人为伐除和保留受害木这两种干扰措施后,任其自然恢复更新,后恢复的林型会大不相同,即对受害木采取不同的干扰措施会对染病松林内林下植被的更新产生不同的影响.基于以上出发点,以松材线虫入侵后采取不同伐除干扰措施的2个马尾松受害群落为研究对象,针对受害木移除和保留两种处理方式,选择α多样性指数函数Rényi指数为测量单位,探讨了不同受害木处理方式下植物多样性的变化规律.结果表明:受害木及时移走的松林内林下灌草多样性比受害木保留的要高.     

Transmission of Pinewood Nematode Through Feeding Wounds of Monochamus carolinensis (Coleoptera: Cerambycidae)

Transmission of pinewood nematode, Bursaphelenchus xylophilus, to mature, field grown Scots pines through feeding wounds of Monochamus carolinensis was investigated by caging nematode-infested beetles on pine branches for 24 hours. Nematodes were transmitted to 31 of 64 branches. Frequency of successful transmission was independent of the sex of the beetle but dependent upon beetle age. Transmission frequencies were highest for beetles 2, 3, and 4 weeks after emergence as adults. The number of nematodes transmitted per branch was low and did not differ between beetle sexes or among beetle age categories. The number of nematodes extracted per branch was correlated with the number of nematodes carried per beetle but was not correlated with the feeding area on the branch.     

Nematicidal and Propagation Activities of Thyme Red and White Oil Compounds toward Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae)

The toxic and propagation effects on Bursaphelenchus xylophilus of 28 Thymus vulgaris red oil and white oil compounds were examined using direct contact and cotton ball bioassays. Results were compared with those of the trunk-injection nematicides emmamectin benzoate, levamisol hydrochloride and morantel tartrate. In direct contact bioassays, geraniol (LC₅₀, 0.47 mg/ml) was the most toxic compound, followed by thymol (1.08 mg/ml), carvacrol (1.23 mg/ml) and terpinen-4-ol (2.61 mg/ml). In cotton ball tests with 20 inactive compounds at 2 mg/cotton ball, p-cymene significantly inhibited propagation (propagation ratio [PR] 8), compared with the castor oil-ethanol-treated control (PR 56). Propagation stimulation was observed with (–)-caryophyllene oxide, (+)-ledene, (+)- and (–)-limonene, linalool oxide, β-myrcene, (–)-α-phellandrene, (+)-α-pinene and γ-terpinene (PR 63–100). The other 10 compounds exhibited low to moderate levels of propagation inhibition (PR 36–56). At 0.1 μg/cotton ball, emmamectin benzoate and morantel tartrate exhibited complete suppression of propagation, whereas a very low level of propagation inhibition was obtained from levamisol hydrochloride (PR 6). In conclusion, propagation-stimulating compounds can exist in plants in addition to nematicidal compounds, and careful use of plant preparations containing high quantities of these compounds is mandatory.     

Occurrence of Bursaphelenchus mucronatus (Nematoda: Aphelenchoididae) and the microhabitat distribution of fungi in declining pine trees in a locale in Korea

A total of 33 pine trees with symptoms of decline were collected in Jeonnam Province, South Korea, and were examined for the presence of nematodes. About 20% of the trees sampled were positive with Bursaphelenchus species. All Bursaphelenchus species were found in recently dead or dying trees. Based on morphological observations, the nematode extracted from the declining pine trees was identified as B. mucronatus. The highly pathogenic pine wood nematode B. xylophilus was not found in any pine trees sampled. B. mucronatus was easily reared on fungus Botrytis cinerea. Twenty one fungal isolates were isolated from dead trees, fallen twigs, and healthy pine trees. The fungal isolates belonged to Trichoderma genus and were dominant in the wood of partially declining pines. The blue‐stain fungi transmitted by the Monochamus beetle were not detected. The B. mucronatus population decreased markedly on Auxarthron reticulatum DY‐2 isolated from soils. The number of nematodes also reduced on Verticillium saksenae A‐1, a nematophagous fungus, and Beauveria bassiana, an entomopathogenic fungus. This observation suggested the fungal production of nematicidal activity against B. mucronatus. When the fungal culture filtrates were also used for nematicidal activity on B. mucronatus, the culture filtrates of A‐1, DY‐2 and B. bassiana showed over 50% mortality within 48 h exposure. The fungi BC4, BC5 and BC6 isolated from declining pine trees inhibited the reproduction of B. mucronatus, and their culture filtrates also expressed nematicidal activity, indicating a possible interaction between the fungi in pine trees and nematodes at microhabitat level.     

Distance effect of co-occurring tree species on pine wilt disease incidence inPinus densiflora seedlings inoculated withBursaphelenchus xylophilus

Field-grownPinus densiflora seedlings were inoculated withBursaphelenchus xylophilus and the incidence of pine wilt disease was analyzed with respect to the spatial relationships between pine seedlings and adjacent seedlings of other tree species in a pure pine stand and three stands mixed withAlnus sieboldiana, Sarothamus scoparius or naturally associated species. The disease incidence was 60.9% in a 0–40 cm distance class from the nearestA. sieboldiana seedlings and then decreased with increasing minimum distance. The mean minimum distance between pine seedlings andA. sieboldiana was significantly shorter in diseased seedlings than in healthy ones. The highest disease incidence (53.9%) was found in a 0–40 cm distance class from the nearestS. scoparius, although the relationship with minimum distance was blurred by a high incidence in the 80-cm distance class. The mean minimum distance between pine seedlings was significantly short in diseased seedlings in a pure stand, whereas it was not so short between pine seedlings and other tree species in the two stands mixed withS. scoparius and the naturally associated species. The distance effect on disease incidence was noticeable inA. sieboldiana andP. densiflora at high density. This was not so clear inS. scoparius and was not found in the naturally associated species.     

Relationship of Bursaphelenchus xylophilus Population Density to Mortality of Pinus sylvestris

Seven-month-old Scots pine seedlings were inoculated with water or culture filtrate (controls), with 10,000, or 20,000 (experiment 1), and with 2,500 (experiment 2) Bursaphelenchus xylophilus B.C. isolate nematodes and maintained under defined experimental conditions. Controls did not develop pine wilt disease over a 2-month period. In experiment 1, less than 50% of the inoculum was recovered from the nematode-inoculated seedlings in the first 48 hours, after which the nematode population of both treatments increased exponentially resulting in pine death and approximately equal populations at 216 hours after inoculation. In the second experiment, plant mortality, which was always preceded by 2-3 days of chlorosis and associated stem vascular necrosis, first occurred 14 days after inoculation. The nematode population increased until about day 40 after inoculation and declined thereafter. Nematodes extracted from the roots 2 weeks after inoculation accounted for ca.15% of the total number of nematodes per pine. The study indicates that the rate of nematode reproduction is a factor in pine wilt disease. However, the lack of a linear correlation between the number of nematodes and the timing of pine mortality suggests that the timing of pine death may also depend on the location of nematode damage to the host tissue.     

Potential vector switching in the evolution of Bursaphelenchus xylophilus group nematodes (Nematoda: Aphelenchoididae)

To show the importance of vector switching of nematodes in the evolution of the Bursaphelenchus xylophilus group, we tested a hypothesis that “Bursaphelenchus doui (or its ancestor) was transferred by Acalolepta fraudatrix, Acalolepta sejuncta, and/or Monochamus subfasciatus (or their ancestral species) from broad‐leaved trees to conifers, switched vectors from these cerambycid beetles to Monochamus beetles in conifers, and then evolved into the common ancestor of Bursaphelenchus mucronatus and B. xylophilus.” We used a simple nematode‐loading method to beetles and produced 20 binary combinations of five B. xylophilus group species and four cerambycid beetle species in the tribe Lamiini. The affinity of the nematodes for the beetles was examined based on phoretic stage formation of the nematodes. Phoretic stages of B. doui appeared in all beetle species examined, namely Acalolepta luxuriosa, Psacothea hilaris, A. fraudatrix, and Monochamus alternatus, although the affinity of the nematode for M. alternatus was weak. This finding indicates that B. doui could switch vectors to conifer‐using Monochamus beetles after transfer by A. fraudatrix from broad‐leaved trees to conifers. We conclude that vector switching of nematodes could have potentially happened during the evolutionary history of the B. xylophilus group.     

利用大面积无人机航拍影像研究松材线虫病病死树林间分布规律

本研究使用固定翼无人机拍摄4 200 ha林地,从中选取了广东省河源市和平县阳明镇、紫金县紫城镇、东源县义合镇共3个样地的3 500 ha林地的航拍影像进行分析,用以探究松材线虫Bursaphelenchus xylophilus病死树的空间分布情况,及不同立地因子对疫情的影响,为松材线虫病监测预报提供解决途径。通过Pix4Dmapper软件对航拍的图像进行拼接生成正射影像图(DOM)等成果,然后使用eCognition(易康)软件对影像成果进行分割、分类和信息提取,最后借助ArcGIS平台进行病死树数量统计并获取方位、坡向、坡度、海拔等立地因子信息。结果表明,松材线虫病死树分布均呈聚集分布。使用双对角线法、平行线法、“Z”字法、五点法等不同抽样方法调查发现,仅五点法所得平均数与总体平均数无明显差异(P<0.05)。松材线虫病死树在不同立地因子下均有差异：主要分布在西坡、南坡和东南坡,西坡最多为25.94%,其次是南坡23.57%;主要分布在半阳坡和阳坡,半阳坡占36.54%,阳坡占34.09%;主要分布在凸坡,但随着疫情的发展,凹坡病死树数量逐渐超过凸坡;主要分布海拔区间在30...