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。     

小蠹虫伴生菌研究概况

小蠹虫伴生菌是在植物-小蠹虫-伴生菌系统中,削弱树木抗性、协助小蠹虫侵害的重要因子。伴生菌与小蠹虫的联系和相互适应是在长期协同进化中形成的。寄主树木对伴生菌的抗御作用主要是通过物理防御、化学防御进行的。而伴生菌对寄主树的侵害又常常是与小蠹虫协同作用的。因此,揭示伴生菌在小蠹虫相互生态联系,探讨伴生菌在植物-小蠹虫-伴生菌系统中所扮演的角色,对于防治小蠹虫危害、保护寄主树木具有重要意义。     

树木抗性与小蠹虫生存策略的进化

小蠹虫对寄主树木的入侵危害不仅受到树木原生性抗性的直接影响 ,而且小蠹虫在寄主树木组织内的定居繁衍也受到寄主树木诱导性抗性的制约。寄主树木抗性的强弱决定小蠹虫入侵寄主树木的数量 ,也促使小蠹虫与特定的真菌共生 ,真菌通过对寄主树木生理生化代谢的影响 ,以削弱寄主树木抗虫性 ,从而为小蠹虫在寄主树木组织内的定居创造必备的生存条件。同时小蠹虫为适应真菌的共生和寄主树木的抗虫性 ,促使小蠹虫生存繁衍策略高度进化 ,从而形成小蠹虫—共生真菌—寄主树木三者协同进化共生的关系     

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。     

应用信息化合物防治小蠹虫的研究进展

小蠹虫是世界上重要的森林害虫,常造成森林大面积死亡.小蠹虫多存在于高中山区且其生活隐蔽,利用传统的防治方法很难达到较好的效果.近年来利用化学信息物质防治小蠹虫成为国内外研究的热点.本文简要概述了化学信息物质,特别是寄主次生性物质和小蠹虫信息素对小蠹虫寄主选择行为的影响,以及国内外应用化学信息物质防治小蠹虫的进展.     

秦岭华山松小蠹生态位研究

通过对秦岭林区海拔１６００～２２００ｍ的中山地带华山松小蠹虫种类和生态位的研究,结果表明：在秦岭林区入侵危害寄主华山松的小蠹虫有１９种,其中能构成竞争和共存的小蠹虫主要有１１种。虽然,这１１种小蠹虫具有各自不同的生态位宽度,且存在不同程度的生态位重叠,但各小蠹虫可依据其对寄主树木营养和空间需求的不同、种群密度的相互制约,以及入侵寄主树木时序的差异达到竞争的平衡和共存。秦岭华山松小蠹生态系统的建立,首先是由华山松大小蠹入侵健康华山松,并通过携带蓝变真菌入侵寄主树木,迅速克服寄主树木抗性系统,使寄主树木树势衰弱;其次松六齿小蠹、暗额星坑小蠹和松十二齿小蠹,作为秦岭华山松的主要次期性小蠹,迅速入侵衰弱的寄主华山松;最后其它次期性小蠹虫入侵寄主树木,利用寄主华山松剩余营养和空间。从而实现秦岭华山松立木小蠹生态系统的动态稳定。     

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.     

小蠹科害虫化学信息物质及其对侵害寄主等行为的影响

在综合大量国内外研究成果的基础上,就松树寄主气味、非寄主气味、小蠹虫信息素以及其他化学信息物质对调控小蠹科害虫侵袭寄主林木等的行为,作了系统详细的论述。     

针叶树小蠹对非寄主挥发物的嗅觉识别和行为反应研究评述

针叶树小蠹在扬飞扩散过程中,要有效地依靠嗅觉机制鉴别寄主和非寄主植物的气味,以便在行为反应方面快速定位寄主,降低不利因素对种群的影响。不同的非寄主植物挥发物可以从生境、树种及个体水平上发挥不同的驱避作用。综述非寄主挥发物的范畴和作用、小蠹虫的嗅觉识别及行为反应,提出加强国内针叶树小蠹非寄主挥发物研究与开发的方向,以期为小蠹虫综合管理技术开发提供借鉴和参考。     

景洪农场橡胶树小蠹虫危害现状调查报告

<正> 橡胶树小蠹虫是胶园常见重要害虫之一。近年来,我场的开割胶园因受小蠹虫钻蛀而导致胶树死亡的现象相继发生,危害逐年加重,局部林段已形成重虫害区,被虫蛀死亡的胶树达5％以上,给生产造成较大损失。为了掌握橡胶树小蠹虫种类、危害现状,为今后开展防治工作提供依据。1992年,我场结合热作病虫害普查工作,对橡胶树小蠹虫进行了专题调查。     

Colonisation of native and exotic conifers by indigenous bark beetles (Coleoptera: Scolytinae) in France

Planting exotic conifers offers indigenous forest insects an opportunity to extend their host range and eventually to become significant pests. Knowing the ecological and evolutionary modalities driving the colonisation of exotic tree species by indigenous insects is thus of primary importance. We compared the bark beetle communities (Coleoptera: Curculionidae, Scolytinae) associated with both native and introduced conifers in France. The aim of our study was to estimate the influence of both host- and insect-related factors on the beetles’ likelihood to shift onto new hosts. We considered the influence of host origin (i.e. native vs. exotic), host tree species identity, tree bark thickness and tree taxonomic proximity, as well as insects’ host specificity. A field inventory using trap trees was carried out in two regions in France (Limousin and Jura) during two consecutive years (2006 and 2007) on three European native conifer species [Norway spruce (Picea abies); Scots pine (Pinus sylvestris) and European Silver-fir (Abies alba)] and five North American [Sitka spruce (Picea sitchensis); Eastern white pine (Pinus strobus); Grand fir (Abies grandis); Douglas fir (Pseudotsuga menziesii) and Western red cedar (Thuja plicata)]. A total of 18 indigenous and 2 exotic bark beetle species were collected. All exotic conifer species were colonised by indigenous bark beetle species and no significant difference was observed of the cumulated species richness of the latter between native and exotic tree species (13 vs. 14, P < 0.05). The ability of indigenous bark beetles to shift onto exotic conifers appeared to strongly depend on host species (significantly structuring bark beetle assemblages), the presence of phylogenetically related native conifer species and that of similar resources, in combination with insect host specificity. Host tree species status (native or exotic) also seemed to be involved, but its effect did not seem as essential as that of the previous factors. These findings are discussed in terms of adaptation, plasticity and practical aspects of forest management.     

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。     

Pruning enhances the susceptibility of Picea abies to infection by the bark beetle‐transmitted blue‐stain fungus,Ophiostoma polonicum

Defoliation of conifers occasionally precedes bark beetle attacks, suggesting that a severe loss of foliage and ensuing reductions in carbohydrate availability may enhance host tree susceptibility. To shed light on this question, different degrees of defoliation on young Picea abies were simulated by removing whole whorls of branches from below, the trees retaining 100, 50, or 25% of their original crown biomass. After one week or one year, the trees were inoculated with Ophiostoma polonkum, a tree‐killing fungus transmitted by Ips typographus.

Fungal proliferation and tree mortality increased with increasing levels of pruning. Pruning reduced stem diameter growth, but not carbohydrate reserves in foliage and bark. Foliar N, P, and Ca increased with increasing pruning. The results lend support to the hypothesis that a reduction in the photosynthesis capacity increases host tree susceptibility to a beetle‐fungus attack, and that induced defence against infection depends on efficient translocation of assimilates to the sites of infection.     

Test von Monoterpenen als Zusatz zu Pheroprax® bzw. Chalcoprax® in Pheromonfallen zum Fang des Buchdruckers,Ips typographus L. bzw. des Kupferstechers,Pityogenes chalcographus L. (Col., Scolytidae)

Experiments on monoterpenes in combination with Pheroprax^® and Chalcoprax^® in pheromone traps for catching the bark beetlesIps typographus L. andPityogenes chalcographus L. (Col., Scolytidae) It is highly evident that monoterpenes of the host tree serve as olfactory stimulants for “pioneer-beetles” colonizing first a tree before any bark-beetle-produced aggregation pheromones can lure those beetles to the host. The findings ofRedemann (1993) about a significant increase of spruce engraver catches by addition of both (?)-alpha-pinen and (+)-limonen simultaneously to pheroprax-baited bark beetle traps (Pheroprax^R being the aggregation pheromone ofIps typographus) induced us to conduct field experiments testing the same host volatiles in comparable bark beetle traps baited with either Pheroprax^® or Chalcoprax^® (aggregation pheromone ofPityogenes chalcographus). Despite we used methods considering the influence of place and time on the bark beetle flight activities, in 3 experiments with 30 repetitions in total no monoterpene-induced enhancement oftypographus-catches could be found; the same was true withP. chalcographus (2 experiments, 18 repetitions in total). With respect to the important role of host volatiles also from a practical point of view, it is strongly recommended to repeat experiments like these under different conditions to reveal the reasons of the different findings.     

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.

     

云杉八齿小蠹化学生态的研究进展(鞘翅目,小蠹科)

本文对云杉八齿小蠹化学生态的研究进展进行了综述。云杉八齿小蠹在中欧的大面积爆发激发了广大林业科学工作者对其化学生态学的广泛研究。在寻找寄主的过程中,雄性找到寄主后释放化学信息物质吸引雄性和雌性的聚集。开始发起进攻的小蠹在找寻寄主的过程中能利用寄主树脂作为利己素,并能够在体内解毒后合成可被利用的化学信息物质。在云杉八齿小蠹雄性的中肠中,我们发现9种单萜类化合物,主要是反式马鞭草烯醇和2-甲基3-己烯2-醇,这两种物质被认为是云杉八齿小蠹聚集信息素的主要成分。小蠹二烯醇的含量虽然很低但是能显著提高马鞭草烯醇和2-甲基3-己烯2-醇的野外诱集作用。马鞭草烯酮和小蠹烯醇是反聚集信息素,在调节攻击密度和树皮下的种群密度的过程中起着重要的作用。本文主要综述了寄主抗性、信息素成分和小蠹虫行为之间的关系。野外生测的结果证明利用信息素防治云杉八齿小蠹是行之有效的防治方法。     

Prescribed fire effects on bark beetle activity and tree mortality in southwestern ponderosa pine forests

Prescribed fire is an important tool in the management of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests, yet effects on bark beetle (Coleoptera: Curculionidae, Scolytinae) activity and tree mortality are poorly understood in the southwestern U.S. We compared bark beetle attacks and tree mortality between paired prescribed-burned and unburned stands at each of four sites in Arizona and New Mexico for three growing seasons after burning (2004–2006). Prescribed burns increased bark beetle attacks on ponderosa pine over the first three post-fire years from 1.5 to 13% of all trees, increased successful, lethal attacks on ponderosa pine from 0.4 to 7.6%, increased mortality of ponderosa pine from all causes from 0.6 to 8.4%, and increased mortality of all tree species with diameter at breast height >13 cm from 0.6 to 9.6%. On a per year basis, prescribed burns increased ponderosa pine mortality from 0.2% per year in unburned stands to 2.8% per year in burned stands. Mortality of ponderosa pine 3 years after burning was best described by a logistic regression model with total crown damage (crown scorch + crown consumption) and bark beetle attack rating (no, partial, or mass attack by bark beetles) as independent variables. Attacks by Dendroctonus spp. did not differ significantly over bole heights, whereas attacks by Ips spp. were greater on the upper bole compared with the lower bole. Three previously published logistic regression models of tree mortality, developed from fires in 1995–1996 in northern Arizona, were moderately successful in predicting broad patterns of tree mortality in our data. The influence of bark beetle attack rating on tree mortality was stronger for our data than for data from the 1995–1996 fires. Our results highlight canopy damage from fire as a strong and consistent predictor of post-fire mortality of ponderosa pine, and bark beetle attacks and bole char rating as less consistent predictors because of temporal variability in their relationship to mortality. The small increase in tree mortality and bark beetle attacks caused by prescribed burning should be acceptable to many forest managers and the public given the resulting reduction in surface fuel and risk of severe wildfire.