寄生性天敌对华山松大小蠹种群控制作用评价

对秦岭林区优势先锋虫种华山松大小蠹 Dendroctonus armandi 寄生蜂种群的林问分布规律进行了研究.在标准地调查基础上,选择华山松大小蠹虫害木作为解析木,分期分批采集华山松大小蠹幼虫和蛹进行室内饲养.结果表明:秦岭林区华山松大小蠹有寄生蜂7种.在河谷地带华山松林中寄生蜂种类最多,7种寄生蜂都有分布,总寄生率最高(37.5%～42.5%),其它依次为竹子华山松林、鹿蹄草华山松林、苔草华山松林、山坡下部华山松林;华山松虫害木树干不同部位寄生蜂种群组成和总寄生率不同,华山松大小蠹寄生蜂种群在华山松虫害木树干上的垂直分布与华山松大小蠹种群相吻合,说明华山松大小蠹种群和寄生蜂种群长期以来建立了相互制约而又相互依存的密切关系.     

太白山华山松大小蠹防治初探

华山松大小蠹是为害华山松主要的蛀干害虫,被称为＂华山松的癌症＂,多年来人们一直在探索尚未见一成效显著的办法。本文根据太白山西河营林区地处秦岭北麓的地理位置及气候环境,结合连续几年对深山区华山松林发生的华山松大小蠹虫的监测与防治实践工作,归纳整理的一些采取营林与化学药剂相结合的防治措施,对于周边林区防治华山松大小蠹虫害具有参考价值。     

华山松大小蠹共生真菌对寄主树木的影响

华山松大小蠹共生真菌（ Ｏｐｈｉｏｓｔｏｍａ ｓｐ ．和Ｌｅｐｔｏｇｒａｐｈｉｕ ｍ ｓｐ ．） 是克服寄主华山松树木抗性系统的先导和致死寄主树木的主要原因。华山松大小蠹共生真菌通过对寄主树木木质部树脂道泌脂细胞的分解和菌丝在寄主树木树脂道内的大量繁殖,堵塞寄主树木树脂道,使寄主华山松泌脂系统失去活性和抗性功能。同时,随共生真菌在寄主树木木质部内的发育,菌丝分解寄主木质部薄壁细胞,使寄主树木木质部物质代谢紊乱,导致寄主华山松迅速死亡     

华山松大小蠹带菌部位及贮菌器结构研究

研究了秦岭林区华山松大小蠹带菌部位及贮菌器结构,结果表明：华山松大小蠹成虫具有前胸背板体壁凹陷和刺毛构成的贮菌器,用于携带和传播真菌,其所携带真菌种类以穿孔细帚霉和小线嘴壳为主,以真菌孢子为唯一携带方式,并在在虫入侵健康寄主华山检针携带真菌孢子接种于华山松木质部。华山松大小蠹消化道内不具有含菌细胞和特化的带菌结构,消化道内存在的真菌也没有菌丝发育形成的附着孢或吸盘结构,使真菌不能被有效地贮存或携带     

神农架林区华山松大小蠹危害风险分析

利用景观生态学的研究方法,以神农架林区华山松大小蠹Dendroctonus armandi为研究对象,从华山松Pinus armandii景观空间格局分析林区华山松大小蠹发生情况,并对林区各林场乡镇的风险程度进行分析.结果表明:华山松大小蠹发生与寄主华山松的面积分布占比、斑块密度呈正相关,相关系数R值分别为0.504和...     

松纵坑切梢小蠹(Blastophaqus piniperda L.)生活史的观察及防治方法的研究

松纵坑切梢小蠹亦称松纵道剪枝小蠹、松小蠹等。它是鞘翅目,小蠹虫科的一种小蠹虫。属于松林次期害虫,对于衰弱和濒死的树木为害极为严重。在其成虫补充营养时期严重为害当年新梢,其交尾、产卵及幼虫期为害衰弱和濒死树木干部的韧皮部,严重时可使大片林木枯死。     

华山松大小蠹对华山松韧皮部营养和矿物元素的利用

对健康和蓝变真菌侵染的华山松韧皮部以及华山松大小蠹排泄物中粗蛋白、粗脂肪、粗纤维、淀粉、还原性糖、可溶性总糖、游离态氨基酸和Na,K,Ca,Mg,Fe,Cu,Mn,Zn等8种元素进行分析,结果表明:华山松大小蠹对寄主华山松营养物质的利用率依次为:还原性糖＞粗脂肪＞可溶性总糖＞粗纤维＞淀粉＞粗蛋白.华山松韧皮部的17种游离态氨基酸中含有华山松大小蠹必需的9种氨基酸;华山松大小蠹对寄主华山松韧皮部组织内的Na,K,Ca,Mg,Fe,Cu,Mn,Zn等8种矿物元素需求量存在明显差异,其中对K元素的需求量最大,而对Cu,Mn,Zn 3种元素的需求量较小.同时,华山松大小蠹共生真菌能够加速华山松木质部和韧皮部中营养的分解转化,为华山松大小蠹在被害华山松韧皮部和木质部间的生存和发育创造条件,并加速被害华山松树势的衰弱和死亡.     

华山松16种小蠹(鞘翅目:象虫科:小蠹亚科)前胃结构的形态学

通过光学显微和扫描电镜技术,对危害华山松的16种小蠹前胃形态结构进行观察.根据前胃板的结构特征可以将16种小蠹前胃分成3个类型,这些前胃形态结构的差异可以作为小蠹分类鉴定的辅助手段,且前胃类型与韧皮部小蠹虫在华山松树干上的空间分布相吻合,华山松韧皮部小蠹前胃结构的特化是适应食物类型(营养的累积和质地)的结果.     

化学信息素对小蠹虫入侵危害的调控

评述了小蠹科昆虫化学信息通讯的复杂性和种间多样性，小蠹虫利它素、利己素和信息素在寄主树木选择、入侵、定居和繁殖中的行为调控机制。并讨论了化学信息素合成与分泌对小蠹虫种群密度和生态位宽度，以及天敌昆虫种类和数量动态的影响。     

小蠹虫信息化合物作用研究概述

小蠹虫具有复杂的种间和种内信息化合物,其主要作用是调节和控制对寄主树木的选择、入侵及危害,进而调控小蠹虫在森林生态系统内的种群密度和生态分布。本文简要概述了信息化合物在小蠹虫寄主选择、入侵、定居、繁殖等一系列行为中的作用,并进一步阐述了小蠹虫寄主选择理论,重点阐明了寄主与非寄主植物挥发物的作用。     

松球壳孢菌的致病性研究

实验证明 ,国内供试松球壳孢菌 (Sphaeropsissapinea)的致病力明显高于美国的B型菌株 ,与A型相似 ,致病性较强。B型也能无伤侵入 ,只是发病率明显低于A型。伤口并不是病菌侵入的唯一途径 ,自新梢伸长至针叶发育完全期间 ,病菌可直接侵入树木当年嫩梢并使之枯萎 ;此后 ,随着梢部组织的不断成熟与老化 ,伤口对病菌侵入与危害的作用才得以显现出来 ,无伤接种时不发病或只产生部分枯叶。气孔也是病菌侵入的途径之一。病菌不但可侵入当年新稍 ,而且还可于枝梢的 2a和 3a生处有伤侵入 ,使之染病甚至死亡。油松(Pinustabulaeformis)、赤松 (P .densiflora)、彰武松 (P .densifloravar .zhangwuensis)较樟子松 (Pinussylvestrisvar.mongolica)抗病 ,且彰武松主要表现为“耐病”。幼龄的樟子松较大龄的抗病。树势削弱的枝梢抗病性能降低 ,发病快而重。潜育期和繁殖期的长短与寄主、树势、组织的成熟程度和气温等有关     

混交林中黄斑星天牛选择寄主的行为与寄主抗虫性关系的研究

通过观察混交林中黄斑星天牛选择寄主的行为,认为对不同抗生寄主,它选择寄主的行为不同。它能通过复杂的感觉行为和一定的时间找到混交林中的感性树种并造成严重危害和它们种群密度在感性树种上的上升。这种天牛选择寄主在远距离一般以植物气味定向,近距离则以性信息素 增加种群密度。除视觉外,它的主要感觉行为是触角摆和胫节磨擦,选择到达合适寄主是通过逐步的感觉阶段完成的。树皮粗糙程度,叶片特征,枝条特征及混交林密度     

非寄主挥发物对针叶树小蠹虫作用的研究进展

针叶树小蠹虫不仅能通过信息化学物质识别和回避非寄主生境,而且能识别非寄主树种和不适寄主树。非寄主挥发物,尤其是6碳乙醇等绿叶气体和一些8碳醇等树皮挥发物是代表着非寄主的重要气味信号,在针叶树小蠹虫寻找寄主的过程中有重要意义。本文分别对绿叶气体和非寄主树皮挥发物等的研究基础、小蠹虫对非寄主的回避、影响挥发物释放的因素、非寄主挥发物的采集分析、生物测定方法和非寄主挥发物作用的生态学及进化意义等方面的研究现状和进展进行了综述,认为小蠹虫能在混交林中找到寄主不是单因素决定的,是受多因素影响的结果。非寄主挥发物在针叶树小蠹虫的管理中具有广阔的应用前景。     

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

? Our aim is to present why the hypothesis, that Ophiostomatoid fungi play an important role in the establishment of most bark beetle species on living conifers, is valuable.

? After summarizing knowledge about the relationships of bark beetles with conifers and fungi, we conclude that controversy results from misinterpretations when using fungal pathogenicity to demonstrate the role of Ophiostomatoid fungi in beetle establishment on host trees.

? We demonstrate that fungal pathogenicity is not the right parameter to appreciate the role of fungus in beetle establishment on host trees. We argue that artificial low density inoculations that allow the appreciation of fungus ability to stimulate tree defenses and thus to help beetles in overcoming tree resistance must be used in complement to mass inoculations. In both cases, results must be expressed in terms of tree defense stimulation rather than in terms of tree killing.

1. Fungal species stimulating tree defenses are generally not those that grow the best in the sapwood.
2. We argue that beetle development in the phloem, fungal invasion of the sapwood and phloem, and tree death, occur after tree defenses are exhausted, and that any fungus present in the beetle gallery could thus potentially invade the sapwood after defense exhaustion.

? We conclude that stimulation of the tree defense reactions in both the phloem and the superficial sapwood is a real benefit brought by fungi to the beetles during the first phase of establishment (overcoming tree resistance).

? Considering the origin of the bark beetle fungus associations attacking living trees and their general functioning based on stimulation of tree defenses, we develop three hypotheses:

1. any beetle species would be helped in its establishment in a given tree species by developing an association, even loosely, with a fungus species belonging to the Ophiostomatoid flora of that tree species;
2. the necessity of a considerably low level of tree resistance for fungus extension into the tree is the selection pressure that has led fungi to develop their intrinsic ability to stimulate tree defenses, through their ability to grow into the phloem. This association can be completed by antagonistic fungal species controlling extension of the previous fungal species in the tree tissues;
3. Beetle species using the strategy of overcoming tree resistance are associated with a fungal complex, of which species could assume three roles regarding relationships between beetles and trees: 1- to stimulate tree defenses in the phloem and superficial sapwood, 2- to grow into the sapwood after tree resistance is overcome, and 3- to control phloem extension of the first other two categories. Bringing nutrients to the beetle progeny can be a fourth role.

? We propose that bark beetle — Ophiostomatoid associations can be categorized, based on associations’ frequency and complexity while taking into account beetle aggressiveness. We show that a close correspondence exists between beetles’ aggressiveness and the ability of their main associated fungal species to stimulate the defenses of their host tree.

? We conclude with suggesting that most sapwood invading fungi might be “cheaters” which have taken advantage of the efficiency of the relationship between beetles and fungi that stimulate tree defenses.

     

云南橡胶树小蠹虫研究

云南植胶区橡胶树小蠹虫为4个科17个种的小蠹虫群体,是主要蛀食橡胶树死亡组织的次期性害虫,长期生存在橡胶林中。1990年后,橡胶树小蠹虫为害逐渐明显,表现大量发生,虫害树快速死亡,造成严重的经济损失。经2000～2007年的研究表明:橡胶树小蠹虫种群结构已发生重要变化,活蛀性的角面长小蠹(Platypussecrelus Sampson)、小杯长小蠹(P.calicutus Chapuis)已发展成为优势种,致使橡胶树小蠹虫种群从次要害虫逐渐变为主要害虫,成为橡胶树衰退重要的促进因素(Contributing factors);橡胶树衰退,特别是过度的乙烯利刺激割胶导致的橡胶树衰退,是促变小蠹虫群体结构并逐渐发展成为主要害虫的主要诱因。因此,提高管理水平,调控生产技术,使胶林生态系统达到新的平衡,才是有效地控制橡胶树衰退趋势和控制小蠹虫为害于经济阈值之下的正确途径。     

松属线粒体基因序列变异研究

本研究利用ＰＣＲ和ＰＣＲ产物直接序列分析技术,获得了分属于松属（Ｐｉｎｕｓ）两个亚属Ｐｉｎｕｓ和Ｓｔｒｏｂｕｓ１２个松树种ｃｏｘＩ、ａｔｐ６和ｏｒｆ２５三个线粒体基因ＤＮＡ片段的序列。发现ｃｏｘＩ基因的ＤＮＡ序列在属内没有任何变异,但ａｔｐ６和ｏｒｆ２５在两个亚属间和亚属内出现了较多的碱基置换。这说明尽管裸子植物线粒体基因有较多的ＲＮＡ编辑（ＲＮＡｅｄｉｔｉｎｇ）存在,可促进ＤＮＡ序列的变异,但促进程度因不同基因而异。依据ａｔｐ６和ｏｒｆ２５所做的系统进化树不仅与分类结果一致,而且进一步表明了亚属内种间的亲缘关系。尽管线粒体基因序列变异比叶绿体和核ＤＮＡ变异小,线粒体基因编码序列变异仍适于研究裸子植物亚属甚至组间的系统进化关系。     

Bark beetle (Coleoptera: Scolytidae) diversity in spaced and unmanaged mature lodgepole pine (Pinaceae) in southeastern British Columbia

Variation in the number and diversity of bark beetles in spaced mature lodgepole pine stands in the East Kootenay region of British Columbia was analyzed in relation to location (site), spacing treatment and years following treatment. We analyzed the number of bark beetles and the number of bark beetle species that emerged from stumps or were captured in flight traps in the first five years following spacing. We also investigated the incidence of bark beetle attacks on the remaining trees and the mean dates of emergence from stumps and of capture in flight traps for the common species. Observations were made on three sites, each having three treatments: 4 m × 4 m spacing, 5 m × 5 m spacing, and an untreated control. The mean density of bark beetles emerged from stumps was different among sites and years but not between spacing treatments. There was no statistically significant variation in the number of bark beetle species captured in flight traps by site, spacing treatment, years, or spacing treatment and years. Significantly more bark beetles were captured in the 4 m × 4 m spacing treatment than in the control. The number of bark beetles captured was the highest in the first 2 years following treatment. Up to 26 species of bark beetles, excluding ambrosia beetles, were captured in flight barrier traps. There was no difference in species diversity by site or treatment indicating that species diversity in mature lodgepole pine is relatively stable over large areas. Of the 213 trees that sustained at least 10 attacks by bark beetles on the lower 2 m of the bole, 59.1% occurred in the spaced plots but only 18.2% of those were successful, versus 74.7% success in the infested trees in the control plots. The majority of infested trees contained Ips sp., Dendroctonus valens and D. murrayanae. Of the seven trees attacked by mountain pine beetle (D. ponderosae) only one tree was located in a spaced plot.     

Response of bark beetles and their natural enemies to fire and fire surrogate treatments in mixed-conifer forests in western Montana

Four treatments (control, burn-only, thin-only, and thin-and-burn) were evaluated for their effects on bark beetle-caused mortality in both the short-term (one to four years) and the long-term (seven years) in mixed-conifer forests in western Montana, USA. In addition to assessing bark beetle responses to these treatments, we also measured natural enemy landing rates and resin flow of ponderosa pine (Pinus ponderosa) the season fire treatments were implemented. All bark beetles were present at low population levels (non-outbreak) for the duration of the study. Post-treatment mortality of trees due to bark beetles was lowest in the thin-only and control units and highest in the units receiving burns. Three tree-killing bark beetle species responded positively to fire treatments: Douglas-fir beetle (Dendroctonus pseudotsugae), pine engraver (Ips pini), and western pine beetle (Dendroctonus brevicomis). Red turpentine beetle (Dendroctonus valens) responded positively to fire treatments, but never caused mortality. Three fire damage variables tested (height of crown scorch, percent circumference of the tree bole scorched, or degree of ground char) were significant factors in predicting beetle attack on trees. Douglas-fir beetle and pine engraver responded rapidly to increased availability of resources (fire-damaged trees); however, successful attacks dropped rapidly once these resources were depleted. Movement to green trees by pine engraver was not observed in plots receiving fire treatments, or in thinned plots where slash supported substantial reproduction by this beetle. The fourth tree-killing beetle present at the site, the mountain pine beetle, did not exhibit responses to any treatment. Natural enemies generally arrived at trees the same time as host bark beetles. However, the landing rates of only one, Medetera spp., was affected by treatment. This predator responded positively to thinning treatments. This insect was present in very high numbers indicating a regulatory effect on beetles, at least in the short-term, in thinned stands. Resin flow decreased from June to August. However, resin flow was significantly higher in trees in August than in June in fire treatments. Increased flow in burned trees later in the season did not affect beetle attack success. Overall, responses by beetles to treatments were short-term and limited to fire-damaged trees. Expansions into green trees did not occur. This lack of spread was likely due to a combination of high tree vigor in residual stands and low background populations of bark beetles.     

Association of wildfire with tree health and numbers of pine bark beetles, reproduction weevils and their associates in Florida

Wildfires burned over 200,000 ha of forest lands in Florida from April to July 1998. This unique disturbance event provided a valuable opportunity to study the interactions of summer wildfires with the activity of pine feeding insects and their associates in the southeastern United States. We compared tree mortality with abundance of bark and ambrosia beetles, reproduction weevils and wood borers relative to fire severity. Over 27% of residual live trees in stands that experienced high fire severity died between October 1998 and May 1999. An additional 2–3% of trees that initially survived the fire died during the second year compared to <1% mortality in unburned stands. One year after the fire, more than 75% of the trees surviving in high fire severity stands had roots infected with one or more species of Leptographium and/or Graphium spp. and nearly 60% of the sampled roots were infected. No such fungi were recovered from roots of trees in unburned stands. Significantly, more root weevils, Hylobius pales and Pachylobius picovorus, were captured in unbaited pitfalls in the moderate and high fire severity stands than in the controls. Mean trap catches of Ips grandicollis, Dendroctonus terebrans and Hylastes salebrosus, three common bark beetles that feed on phloem tissue of pines, were lower in Lindgren traps in the fire-damaged areas than in the control stands. In contrast, catches of the ambrosia beetles, Xyleborus spp. and Monarthrum mali, were higher in burned stands than in control stands. The generalist predator, Temnochila virescens (Coleoptera: Trogositidae), showed a strong positive relationship between abundance and fire severity, while the flat bark beetle, Silvanus sp. (Coleoptera: Sylvanidae), exhibited the reverse trend. Our results show that most tree mortality occurred within 1 year of the fire. Ips or Dendroctonus bark beetle populations did not build up in dead and weakened trees and attack healthy trees in nearby areas. The prevalence of Leptographium spp. in roots may be a symptom of, or result in, weakened trees that may affect the trees’ susceptibility to bark beetles in the future.