Ophiostomatoid fungi associated with three spruce-infesting bark beetles in Slovenia

Context

Ophiostomatoid fungi can severely affect the health and economic value of Norway spruce trees (Picea abies). Although the diversity of ophiostomatoid species and their associations with insects have been well-investigated in central and northern Europe, little is known about the conditions in south-eastern Europe.

Aim

This study aims to study the assemblages of ophiostomatoid fungi associated with three bark beetle species (Ips typographus, Ips amitinus, and Pityogenes chalcographus) that infect Norway spruce in Slovenia.

Methods

Bark beetles were sampled in four phytogeographic regions in Slovenia. The fungi found on the bark beetles were identified based on morphology, DNA sequence comparisons of ITS regions and phylogenetic analysis. The species compositions of the fungal associates of the three insect species were compared and the pairwise associations of the occurrence of the fungal species were analysed.

Results

Thirteen different species were found. The most commonly encountered fungal associates of the beetles were Ophiostoma bicolor, Ophiostoma brunneo-ciliatum, Grosmannia piceiperda, Ophiostoma ainoae, Ceratocystiopsis minuta, and Grosmannia penicillata. The composition of the fungal associates differed among the bark beetle species, but not among the phytogeographic regions.

Conclusions

This study confirms that ophiostomatoid species are common associates of the investigated bark beetle species. Many ophiostomatoid species have strong host associations. I. typographus and P. chalcographus can act as effective vectors for O. bicolor, O. ainoae, G. piceiperda and O. brunneo-ciliatum, whereas I. amitinus often carries G. piceiperda and C. minuta in Slovenian forests.     

小蠹虫伴生长喙壳类真菌研究进展

小蠹虫与多种微生物具有密切的关系,其中小蠹虫与伴生真菌种间关系存在着相对稳定性和依赖性.在小蠹虫蛀干过程中,伴生真菌随蠹虫携带进入树木木质部和韧皮部,通过消耗寄主的养料,堵塞木质部筛管,破坏韧皮细胞,对寄主树木产生危害作用.在小蠹虫众多的伴生真菌里,尤以长喙壳类真菌(ophiostomatoid fungi)在小蠹虫种群建立、协同克服寄主抗性、引起树木病害等方面起到重要作用,带来直接和间接的经济损失.该文对小蠹虫与长喙壳类真菌伴生关系、长喙壳类真菌种类等做一综述.     

Ophiostomatoid fungi associated with bark beetles onAbies veitchii in wave-regenerated forests

Relationships between tree mortality and bark beetle infestation onAbies veitchii at the wave-regenerated forest in Mt. Asahi, Okuchichibu area were investigated. Most of the firs with green needles and newly developed current year’s shoots in the dieback zone were heavily infested by bark beetles before the death of the trees. After heavy infestation of beetles, about half of the infested firs died within the year, and the other half died in the next year. When the species composition of bark beetles and associated ophiostomatoid fungi were investigated in Mt. Asahi and also at a typical wave-regenerated forest in Mt. Shimagare, Yatsugatake area,Cryphalus montanus andC. piceae were dominant beetle species for Mt. Asahi and Mt. Shimagare, respectively.Ophiostoma subalpinum andO. europhioides were dominant fungal species at both wave-generated forests. BecauseO. subalpinum was detected more frequently from deeper areas of sapwood thanO. europhioides, it was suggested that the fungal species may accelerate the death of stressed firs in wave-regenerated forests. Contribution No. 169, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Population levels and flight phenology of bark beetle predators in stands with and without previous infestations of the bark beetle Tomicus piniperda

Relative population levels and flight periods of Tomicus piniperda (L.) (Col.: Scolytidae) and two of its main predators, Thanasimus formicarius (L.) (Col.: Cleridae) and Rhizophagus depressus (F.) (Col.: Monotomidae) were monitored in 1995 in eight Scots pine stands in central Sweden using flight barrier traps (five per stand) baited with α-pinene and ethanol. In four of the stands (A-stands) T. piniperda and associated species had reproduced the previous year in stumps and slash remaining after thinnings conducted in the winter of 1993/1994. In the remaining four stands (B-stands) no bark beetle breeding material had been available during the five preceding years. In addition, the flight periods of the species were monitored in one stand in 1996. In 1995 the catches of T. piniperda and R. depressus were four to five times higher in the A-stands than in the B-stands, whereas there was no difference in the catch of T. formicarius between the two kinds of stands. The T. formicarius/T. piniperda ratio was ca. 50 times higher in the B-stands compared with the A-stands during the period of clerid predation on colonising bark beetle adults and six times higher during the period of clerid oviposition. The R. depressus/T. piniperda ratio was only slightly higher in the A-strands than in the B-stands as a result of the spatial distribution of T. piniperda. Three additional species of bark beetle predators were caught: Glischrochilus quadripunctatus (L.), Pityophagus ferrugineus (F.) (Col.: Nitidulidae) and Rhizophagus ferrugineus (Payk.) (Col.: Monotomidae). Based on their seasonal abundance the bark beetle predators can be divided into three temporal groups: the first species to occur in the spring is G. quadripunctatus, the second group consists of R. depressus and T. formicarius, and the last species to initiate flight are R. ferrugineus and P. ferrugineus.     

纵坑切梢小蠹伴生菌--云南半帚孢毒素作用机理的初步研究

用纵坑切梢小蠹伴生菌——云南半帚孢Laeptographium yunnanense的毒素处理后，云南松和华山松体内与抗病性密切相关的过氧化物酶、多酚氧化酶和苯丙氨酸解氨酶的活性都明显地下降，表明该毒素可以通过抑制寄主体内与抗性有关的酶的活性来削弱寄主的抗性，从而有利于菌在寄主体内侵染生长。云南松的酶活性下降的程度较大，而华山松的酶活性较高，毒素处理后活性受抑制的程度相对较小，这表明华山松对云南半帚孢的抗御能力较云南松的强，这也是云南境内云南松受害严重而华山松受害轻微的重要原因之一。     

Ophiostomatoid fungi associated with root‐feeding bark beetles on Scots pine in Poland

Ophiostomatoid fungi are known to be associated with various species of bark beetles. However, information about fungal associates of root‐feeding bark beetles in Europe is still fragmentary. For this reason, the fungal associates of Hylastes ater, H. opacus and Hylurgus ligniperda on Pinus sylvestris were isolated and identified. A total of 743 fungal isolates were collected and separated into 10 morphological groups. Analyses of ITS rDNA and partial β‐tubulin gene sequences confirmed that these groups represented distinct species. The 10 species included a total of 13 associations between fungi and bark beetles that had not been recorded previously. All of the bark beetles examined were frequently associated with ophiostomatoid fungi. The fungal diversity and relative abundance of species were very similar in the three species of root‐feeding bark beetles. The most commonly encountered associates of these beetles were Grosmannia radiaticola, Leptographium lundbergii, L. procerum and L. truncatum. Insect infestation data furthermore suggest that Hylastes spp. and Hg. ligniperda are also important vectors of the fungal pathogen Sphaeropsis sapinea.     

纵坑切梢小蠹伴生菌危害机理的研究

该文对纵坑切梢小蠹伴生菌Leptographium yunnanense的危害机理作了初步研究，结果表明，L.yunnanense在与小伴随侵入后，产生致病毒素对寄主树林进行危害，从而辅助纵坑切梢小蠹成功定殖于寄主树木内，该毒素在低浓度条件下仍维持一定的致病力，进一步表明伴生菌在小蠹虫成功蛀害的过程中具有重要的作用。     

Bursaphelenchus fungivorus (Nematoda: Aphelenchida) associated with Orthotomicus erosus (Coleoptera: Scolitydae) in Spain

A survey of the xylophagous insects in the conifer forests, mainly Pinus pinaster woodlands, in Spain was carried out in order to study the phoretic vectors of nematodes of the genus Bursaphelenchus. Fifteen environmental sites were characterized on the bases of altitude, rainfall, temperature and conifer species. Specimens of Orthotomicus erosus (n = 3476) were captured of which 59% carried nematodes under their elytrous, most of them were aphelenchid fungal‐feeding nematodes, but B. fungivorus was found on the beetles from Las Cumbres, Villa Blanca, (Huelva), southern Spain, which represent the first record of O. erosus as vector of a Bursaphelenchus sp. The nematode is characterized by morphometric and biomolecular techniques and distribution and ecology of the insect is discussed.     

纵坑切梢小蠹分子生物学研究进展

纵坑切梢小蠹是欧亚大陆的主要森林害虫之一。文章系统综述了目前国内外分子生物学技术。包括PCR扩增后电泳分析、PCR-RAPD、PCR—RFLP分析和DNA序列分析等技术在纵坑切梢小蠹研究中所取得的一些重大成果,重点介绍了纵坑切梢小蠹起源及与近缘种的遗传学关系等最新研究进展。     

石林县云南松纵坑切梢小蠹危害及其综合治理措施

对石林县云南松纵坑切梢小蠹的危害情况进行调查分析,从石林县森林资源特点、气候因子、立地条件以及林分自身状况等方面探讨松小蠹发生危害的原因,并根据松小蠹的生物学、生态学习性,从监测检疫、营林措施、生化防治等方面提出综合治理措施.     

云南松纵坑切梢小蠹危害及生物学特性研究

纵坑切梢小蠹Ｔｏｍｉｃｕｓｐｉｎｉｐｅｒｄａ在云南分布很广，８０年代以来，在昆明、红河、楚雄３地、州３０个县的云南松人工林内猖獗危害，直接经济损失６０００余万元。该虫在云南１ａ一代，全年危害，无明显的越冬现象。每年５～１１月蛀梢，１１～翌年５月蛀干，树皮下各虫态种群高峰期出现在２～５月，此时是清理蠹害木的最佳时期。成虫干转梢及由梢转干在林间扬飞期１～１４ｄ，集中扬飞３～４ｄ，扬飞期对防治成虫有重要意义     

应用聚集信息素监测与防治纵坑切梢小蠹

监测和防治试验结果表明：最好的诱芯9诱集效果是对照诱集效果的7706．8倍，是饵木的20．49倍；效果中等的诱芯1的诱集量是对照的4288．4倍，是饵木的11．4倍；效果最差的诱芯5诱集量为对照的830倍，是饵木的2．19倍。这一结果肯定了聚集信息素诱虫灵敏度高、效果好的特性。同时虫口密度、有虫株率和梢被害率3项指标的减退率证实了应用聚集信息素防治纵坑切梢小蠹的效果显著可靠。其虫口密度减退率平均为94．35％，有虫株率减退率平均为87．7％，被害梢减退率为88．39％。     

土壤物理性质与纵坑切梢小蠹发生初探

松纵坑切梢小蠹是一种严重危害松属树种的世界性蛀干害虫，在云南省西，中，南依无，轻，中，重度危害，选择8个试验点，建立48块调查标地，作危害调查与土壤剖面，收集土壤样本，作室内分析得出，松纵坑切梢小蠹危害与土壤质地，土壤结构，土壤砾质关系密切，与土壤容重，萎蔫点，植物可利用水无明显关系，依此结果，对切梢小蠹的发生规律与综合防治进行了初探。     

云南松林施肥对防治纵坑切梢小蠹虫作用初探

１９９４年和１９９５年在玉溪市北城镇刺桐关办事处石狗头村，云南松纵坑切梢小蠹虫危害的云南松林中，进行了施肥试验。施肥后的云南松被害株率和蠹害指数平均下降２２．６９％和３３．７％，而未施肥的云南松被害株率和蠹害指数平均下降１１．７３％和１８．３％，被害株率和蠹害指数实际平均下降１０．９６％和１５．４％。试验证明，通过施肥，增强树势，能提高云南松对纵坑切梢小蠹虫危害的抵御能力，起到间接防虫的效果     

Monoterpene composition of the preformed and induced resins of Scots pine,and their effect on bark beetles and associated fungi

Inoculations of fungi or introductions of insects were performed on Scots pines. The monoterpene composition of the induced resin differed from that of preformed resin, but did not depend on the nature of the aggression on a same tree. There were variations in the composition of induced resin according to tree. Mycelial growth was strongly limited, more by the increase in resin quantity and total monoterpene quantity than by the qualitative changes of the monoterpene composition. Monoterpenes appeared very toxic for Tomicus piniperda, but not for Ips sexdentatus.     

曲靖地区松纵坑切梢小蠹生物学特性及综合防治

自 1997年以来 ,在沾益县菱角乡和白水镇蠹害林区内设置样地 ,通过连续几年的观察 ,对小蠹虫的生活史 ,成虫蛀梢、蛀干危害习性进行了系统地研究 ,并组建了纵坑切梢小蠹自然种群生命表 ,通过对 10 0 0hm2 的受蠹害林区的综合防治 ,平均受害株率从防治前的 6 1 5 %下降到 17 8% ,受害梢率从 34 9%下降到 10 4 % ,效果显著     

纵坑切梢小蠹伴生菌云南半帚孢毒素活性的生物检测

比较研究了不同生物检测材料及方法在纵坑切梢小蠹伴生菌——云南半帚孢毒素的生物活性检测上的适应性，结果表明该毒素不仅对云南松产生病害作用，对思茅松和华山松同样产生病害作用。用切根幼苗为材料对该毒素进行生测，所需时间虽较短，但幼苗所产生的症状较复杂，不易观察和确定；以松树及其木段为材料将该毒素进行接种试验，则在韧皮部位形成明显的反应区，与接菌产生的反应症状一样，容易确定，但木段上出现反应症状的时间较短，因此，以木段为材料，采用接种法进行该毒素活性检测较好。     

利用云南松物候测报松纵坑切梢小蠹发生期的研究

１９９４～１９９５年，在大理州祥云县下庄乡云南松中龄林内选定３０株样木，进行云南松物候与相应小蠹虫虫情观察。结果为：发生期与物候的相关值为０．９７３２，发生期与温度的相关值为０．８８０５，发生期与湿度的相关值为０．８８８６。因此利用物候作为发生期的测报指标是可行的。     

攀西地区云南松切梢小蠹大发生的原因分析和防治对策探讨

云南松切梢小蠹虫在攀枝花市的发生面积已经达到3．35万hm^2，是攀枝花市的主要森林病虫害。本文分析了该害虫在攀枝花市爆发的原因，总结和探讨了防治对策。     

温度对纵坑切梢小蠹伴生菌——云南半帚孢生长的影响

本文研究了纵坑切梢小蠹伴生菌云南半帚孢Leptographium yunnanense在不同温度下，在PDA培养基，云南松木段和活树上的生长变化情况，结果表明：在5－20℃温度范围内，真菌的生长随温度的升高而加快，云南松韧皮反应区长度逐渐增大；在20－35℃温度范围内，真菌的生长随温度的升高而逐渐减弱，韧皮反应区逐渐减小，说明温度变化使真菌的生长力与云南松的抗性之间的对比力量改变，从而导致真菌的生长长度和韧皮反应区发生相应变化。