不同小蠹类与天牛类引诱剂联用对蛀干甲虫的林间诱捕效果

松墨天牛Monochamus alternatus Hope是传播松材线虫病的主要媒介,引诱剂是抑制松墨天牛种群数量的无公害调控有效方式之一。本研究通过在中国浙江富阳的林间试验测定了6种小蠹类引诱剂与1种天牛引诱剂不同组合联用对松墨天牛成虫以及其他蛀干害虫的诱捕效果。结果表明： 横坑切梢小蠹Tomicus minor引诱剂3-carene-10-ol、云杉八齿小蠹Ips typographus引诱剂2-methyl-3-buten-2-ol、欧洲榆小蠹Scolytus multistriatus引诱剂4-methyl-3-heptanol和纵坑切梢小蠹T. piniperda引诱剂verbenol分别与松墨天牛引诱剂联用后,对松墨天牛的引诱效果无显著性差异(P<0.05)。西部松大小蠹Dendroctonus brevicomis 引诱剂exo-brevicomin或黄杉大小蠹D. pseudotsugae引诱剂1-methylcyclohex-2-en-l-ol与松墨天牛引诱剂联用后对松墨天牛的诱捕效果有减弱的趋势。另外,与单独使用中国天牛引诱剂相比,小蠹类引诱剂与其联用后在诱捕其他蛀干害虫的种类和个体数量上均有所减少。     

Phloem parenchyma cells are involved in local and distant defense responses to fungal inoculation or bark-beetle attack in Norway spruce (Pinaceae)

The anatomical response of Norway spruce bark polyphenolic parenchyma cells (PP cells) to inoculation with the phytopathogenic fungus Ceratocystis polonica and attack by its bark-beetle vector Ips typographus was examined. Fungal inoculation on the periderm surface had no effect, while inoculation just below the periderm or halfway into the phloem (mid-phloem) generated detectable responses within 3 wk. The responses included increase in PP cell size and in periodic acid-Schiff's staining of PP cell phenolics, wound periderm initiation from PP cells, and cambial zone traumatic resin duct formation. Fungi were not seen in samples 3 wk after subperiderm or mid-phloem inoculation, but were found in some samples 6 and 9 wk after mid-phloem inoculation. In contrast, inoculations into the cambium resulted in partial (3 wk) or complete (6 and 9 wk) fungal colonization and death of tissue in the infected area. This indicates that PP cells have defenses capable of inhibiting fungal growth. Samples taken near bark-beetle galleries had similar anatomical responses as inoculated samples, validating the inoculation approach to studying defense responses in spruce. These results show that PP cells represent not only a constitutive defense system, but are also involved in local and remote inducible defenses against fungal and beetle attack.     

Priming of inducible defenses protects Norway spruce against tree-killing bark beetles

Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short-lived model plants such as Arabidopsis, but little is known about this phenomenon in long-lived plants like spruce. We compared the effects of pretreatment with sublethal fungal inoculations or application of the phytohormone methyl jasmonate (MeJA) on the resistance of 48-year-old Norway spruce (Picea abies) trees to mass attack by a tree-killing bark beetle beginning 35 days later. Bark beetles heavily infested and killed untreated trees but largely avoided fungus-inoculated trees and MeJA-treated trees. Quantification of defensive terpenes at the time of bark beetle attack showed fungal inoculation induced 91-fold higher terpene concentrations compared with untreated trees, whereas application of MeJA did not significantly increase terpenes. These results indicate that resistance in fungus-inoculated trees is a result of direct induction of defenses, whereas resistance in MeJA-treated trees is due to defense priming. This work extends our knowledge of defense priming from model plants to an ecologically important tree species.     

Anatomical defences against bark beetles relate to degree of historical exposure between species and are allocated independently of chemical defences within trees

Conifers possess chemical and anatomical defences against tree‐killing bark beetles that feed in their phloem. Resins accumulating at attack sites can delay and entomb beetles while toxins reach lethal levels. Trees with high concentrations of metabolites active against bark beetle‐microbial complexes, and more extensive resin ducts, achieve greater survival. It is unknown if and how conifers integrate chemical and anatomical components of defence or how these capabilities vary with historical exposure. We compared linkages between phloem chemistry and tree ring anatomy of two mountain pine beetle hosts. Lodgepole pine, a mid‐elevation species, has had extensive, continual contact with this herbivore, whereas high‐elevation whitebark pines have historically had intermittent exposure that is increasing with warming climate. Lodgepole pine had more and larger resin ducts. In both species, anatomical defences were positively related to tree growth and nutrients. Within‐tree constitutive and induced concentrations of compounds bioactive against bark beetles and symbionts were largely unrelated to resin duct abundance and size. Fewer anatomical defences in the semi‐naïve compared with the continually exposed host concurs with directional differences in chemical defences. Partially uncoupling chemical and morphological antiherbivore traits may enable trees to confront beetles with more diverse defence permutations that interact to resist attack.     

针叶树树脂的抗害功能及抗害机制

害虫及其共生真菌是针叶树生长、繁衍的一个灾害性的问题,在漫长的进化过程中,很多针叶树种发展了高度发达的固有和诱导树脂防御系统来抵御侵害。树脂的抗害过程,也即树脂的分泌过程,树脂是由单萜、蓓半萜和二萜组成的复杂混合物。文章介绍树脂的组成及其抗害功能,分析外界环境条件对树脂防御功能的影响,阐述诱导树脂生物合成的途径、路线及其一般规律和树脂萜的基因鉴定,讨论开发、利用树脂优良特性保护针叶树的前景。     

危害松树的小蠹虫与其伴生菌的相互关系

危害健康松属植物的小蠹虫经常与一些特殊的真菌相联系。在小蠹虫危害松属植物的过程中,这些真菌被小蠹虫的一些特殊结构或者体表携带到松属植物上。小蠹虫与其伴生菌的联系表明小蠹虫和其伴生菌之间是一种互惠互利的关系。伴生菌随小蠹虫扩散而被带到新的寄主树木。而伴生菌或作为小蠹虫的食物来源,但更重要的是,有些伴生菌能够通过其菌丝渗透寄主组织,释放毒素,致死寄主树木,以帮助小蠹虫降低寄主抗性。许多研究致力于探索小蠹虫/伴生菌联合体与寄主树木之间关系的特征和确定小蠹虫与其伴生菌相互关系在生态学上的意义。然而,不同小蠹虫和其伴生菌所组成的共生体系,不同小蠹虫的种群数量,和不同环境条件下同种小蠹虫与其伴生菌相互作用方式的差异使我们在研究小蠹虫和其伴生菌这个共生体系时,对它们各自在成功聚集寄主树木过程中所发挥的重要作用的概括变得非常困难。     

New species of bark beetles from the Rovno amber (Insecta: Coleoptera: Scolytidae)

Two new species of bark beetles are described from the Late Eocene Rovno amber. Xylechinus mozolevskae sp. nov. (Hylesininae: Tomicini) is the first fossil representative of this genus, differing from recent species in having large triangular scales along the suture. Taphramites rovnoensis sp. nov. (Scolytinae: Dryocoetini) differs from the closest species, T. gnathotrichus from Baltic amber, in the presence of short thin hairs on the elytra.     

Specialized phloem parenchyma cells in Norway spruce (Pinaceae) bark are an important site of defense reactions

The bark anatomy of Norway spruce clones that were resistant or susceptible to Ceratocystis polonica, a bark-beetle-vectored fungal pathogen, was compared. The major difference concerned the axial parenchyma cells, called polyphenolic parenchyma (PP cells) because of their vacuolar deposits. The phenolic nature of the deposits was indicated by autofluorescence under blue light, and immunocytochemical studies demonstrating PP cells are enriched in phenylalanine ammonia lyase (EC 4.3.1.5), a key enzyme in phenolic synthesis. Susceptible-clone PP cells occurred as single rows filled with dense deposits. The resistant clone had 40% more PP cells, which occurred in rows two cells thick plus as individual cells scattered among the sieve cells and had lighter deposits. Trees inoculated with fungus were analyzed but a distinct fungal response could not be separated from the general wound response. In the resistant clone, phenolic bodies were reduced in size and density or disappeared completely 12 d after wounding, and PP cell size increased. The susceptible-clone phenolics and cell size changed only slightly. These data show that PP cells are active in synthesis, storage, and modification of phenolics in response to wounding, providing an important site of constitutive and inducible defenses.     

Long‐distance dispersal of non‐native pine bark beetles from host resources

1. Dispersal and host detection are behaviours promoting the spread of invading populations in a landscape matrix. In fragmented landscapes, the spatial arrangement of habitat structure affects the dispersal success of organisms. 2. The aim of the present study was to determine the long distance dispersal capabilities of two non‐native pine bark beetles (Hylurgus ligniperda and Hylastes ater) in a modified and fragmented landscape with non‐native pine trees. The role of pine density in relation to the abundance of dispersing beetles was also investigated. 3. This study took place in the Southern Alps, New Zealand. A network of insect panel traps was installed in remote valleys at known distances from pine resources (plantations or windbreaks). Beetle abundance was compared with spatially weighted estimates of nearby pine plantations and pine windbreaks. 4. Both beetles were found ≥25 km from the nearest host patch, indicating strong dispersal and host detection capabilities. Small pine patches appear to serve as stepping stones, promoting spread through the landscape. Hylurgus ligniperda (F.) abundance had a strong inverse association with pine plantations and windbreaks, whereas H. ater abundance was not correlated with distance to pine plantations but positively correlated with distance to pine windbreaks, probably reflecting differences in biology and niche preferences. Host availability and dispersed beetle abundance are the proposed limiting factors impeding the spread of these beetles. 5. These mechanistic insights into the spread and persistence of H. ater and H. ligniperda in a fragmented landscape provide ecologists and land managers with a better understanding of factors leading to successful invasion events, particularly in relation to the importance of long‐distance dispersal ability and the distribution and size of host patches.     

Interaction of pre-attack and induced monoterpene concentrations in host conifer defense against bark beetle-fungal complexes

Two pine species (Pinus resinosa, P. banksiana) responded to inoculation with fungi carried by bark beetles by rapidly increasing monoterpene concentrations at the entry site. Changes in total monoterpenes were more pronounced than changes in proportionate compositions. The extent and rate of host response was affected by fungal species, the viability of the inoculum, and host tree species. In general, host responses were highest to fungi that are phytopathogenic and consistently associated with the major bark beetles in the study region. Simple mechanical wounding cannot account for the observed allelochemical changes, as aseptic inoculations elicited only minor reactions. Similarly, inoculation with autoclaved inviable fungi generally elicited intermediate responses, suggesting that both structural and metabolic fungal properties are important. Responses by jack pine, P. banksiana, were generally more rapid and variable than those of red pine, P. resinosa. Dose-toxicity experiments with synthetic compounds demonstrated that monoterpene concentrations present in vivo only a few days after simulated attack are lethal to most beetles. Constitutive (pre-attack) monoterpene levels can also exert some toxicity. Because bark beetles engage in pheromone-mediated mass attacks that can deplete host defenses, constitutive monoterpene levels, while a necessary early phase of successful plant defense, appear insufficient by themselves. Such interactions between constitutive and induced defense chemistry may be important considerations when evaluating general theories of plant defense.     

Field response of non‐target beetles to Ips sexdentatus aggregation pheromone and pine volatiles

Although mass trapping cannot be a definitive control measure, it is one of the few ones available to contain the destruction of millions of cubic metres of conifer forests perpetrated every year worldwide by bark beetles. However, using bark beetle aggregation pheromones during both monitoring and control programs may negatively affect other saproxylic insects. The aim of this study was to describe the response of both Ips sexdentatus and its saproxylic beetle associates, especially predators, to traps baited with a commercial blend of I. sexdentatus aggregation pheromone. Furthermore, the usefulness of adding pine volatiles, such as (?)‐α‐pinene and ethanol, to the pheromone was discussed. The commercial blend proved to be attractive to I. sexdentatus adults, both when used alone and together with pine volatiles. Pheromone attractiveness, however, was lessened by the addition of the volatiles. The pheromone blend proved to be attractive to Thanasimus formicarius, as well as to other predator species. Overall, although during our study, traps baited only with (?)‐α‐pinene and ethanol attracted some predator specimens, I. sexdentatus pheromone traps were more attractive. Our study confirms that calendar differences in flight activity between the bark beetle and its predators are substantial; therefore, they should be taken into account when planning control measures. According to our data, the commercial blend of I. sexdentatus pheromone seems to be the most effective, among the baits used, in catching I. sexdentatus adults, while reducing the impact on T. formicarius.     

Attack preference of Ips pini on Pinus ponderosa in northern Arizona: tree size and bole position

1 The present study investigated the influence of tree size and bole position on selection of ponderosa pines (Pinus ponderosa Dougl. ex Laws.) by Ips pini Say (Coleoptera: Curculionidae: Scolytinae) in a northern Arizona forest. Ips pini were attracted to lower and upper bole positions with pheromone lures, and the number of attacks counted. In addition, tree phloem and bark thickness, resin flow in response to wounding and characteristics of tree water and carbon relations were all measured. 2 Bark thickness was the most strongly related tree characteristic to number of I. pini attacks. Thin bark and a high number of attacks occurred at the lower bole position of 10‐cm diameter trees and upper bole positions of 23‐, 35‐, and 50‐cm diameter trees. 3 Phloem thickness increased directly with tree size, was greater at the upper bole compared with the lower bole, but was not associated with number of attacks. 4 Resin flow did not differ strongly over tree sizes or bole positions, and was not related to number of I. pini attacks. Attacks were not related to characteristics of tree carbon and water relations measured during I. pini flights.     

Reproductive performance of clonal and sexual bark beetles (Coleoptera: Scolytidae) in the field

In Ips acuminatus (Gyll.) parthenogenetic females occur together with sexual females and with sexual males upon which they depend for sperm. In a reciprocal‐transplant experiment, I studied fecundity differences among parthenogenetic and sexual females from two populations that differ dramatically in the proportion of clonal females. In a second experiment, I studied competition between larvae from different mothers and between females from the two source populations. Fecundity measured by the number of eggs per egg tunnel was influenced by the ambient environment at the sites of the experiment as well as the origin of the female, and was generally higher for clonal than for sexual females at both sites. In experimental groups where larvae competed with larvae from their own population (pure treatments), the number of surviving pupae was significantly lower than in groups where females from the two source populations were mixed. The high fecundity of clonal females makes coexistence of the two types of females difficult to explain. It makes the reproductive advantage associated with clonality in I. acuminatus even higher than the two‐fold difference due to asexuality per sé. The significant differences in the number of pupae in mixed vs. pure groups suggest ecological divergence between sexual and clonal females. This would make the mortality of larvae not only density dependent, but also frequency dependent, which could explain the coexistence of sexual and clonal females.     

Terpenoid and other extractives of western white pine bark

A detailed chemical analysis of the benzene extract of western white pine bark was conducted. The extract consisted of 13% phlobaphenes, 18% strong acids, 21% polar weak acids, 6.5% fatty acids, 9.5% resin acids, and 32% neutrals. The fatty acids consisted mainly of C_20:0, C_22:0, and C_24:0 acids. The resin acids were identified as: isopimaric, anticopalic, dehydroabietic, sandaracopimaric, abietic, 6,8,11,13-abietatetraen-18-oic and pimaric acids. The neutrals on saponification gave fatty acids, sterols, wax alcohols, nonsaponifiables, and other components. The esterified fatty acids consisted primarily of the C_16:0, C_18:0, C_20:0 and C_24:0 acids. The sterols included major amounts of sitosterol, campesterol, and stigmasterol, and traces of cholesterol. Over 70 individual compounds were isolated and identified from the nonsaponifiables. These included borneol, sesquiterpenes, diterpenes, steroidal ketones, as well as lanostane and serratane triterpenes. The characterization of12 new natural products or natural products isolated for the first time from Pinus species is reported.     

Olfactory recognition and behavioural avoidance of angiosperm nonhost volatiles by conifer-inhabiting bark beetles

Abstract 1 When searching for suitable hosts in flight, especially in mixed forests, conifer‐inhabiting bark beetles will encounter not only suitable host trees and their odours, but also unsuitable hosts and nonhost trees. Rejection of these trees could be based on an imbalance of certain host characteristics and/or a negative response to some nonhost stimuli, such as nonhost volatiles (NHV). 2 Recent electrophysiological and behavioural studies clearly indicate that conifer‐inhabiting bark beetles are not only able to recognize, but also to avoid, nonhost habitats or trees by olfactory means. Green leaf volatiles (GLV), especially C₆‐alcohols, from the leaves (and partly from bark) of nonhost angiosperm trees, may represent nonhost odour signals at the habitat level. Specific bark volatiles such as trans‐conophthorin, C₈‐alcohols, and some aromatic compounds, may indicate nonhosts at the tree species level. Flying bark beetles are also capable of determining whether a possible host is unsuitable by reacting to signals from conspecifics or sympatric heterospecifics that indicate old or colonized host tree individuals. 3 Combined NHV signals in blends showed both redundancy and synergism in their inhibitory effects. The coexistence of redundancy and synergism in negative NHV signals may indicate different functional levels (nonhost habitats, species, and unsuitable hosts) in the host selection process. Combinations of NHV and verbenone significantly reduced the number of mass attacked host trees or logs on several economically important species (e.g. Dendroctonus ponderosae, Ips typographus, and I. sexdentatus). 4 We suggest a semiochemical‐diversity hypothesis, based on the inhibition by NHV of bark beetle host‐location, which might partly explain the lower outbreak rates of forest insects in mixed forests. This ‘semiochemical‐diversity hypothesis’ would provide new support to the general ‘stability‐diversity hypothesis’. 5 Natural selection appears to have caused conifer‐inhabiting bark beetles to evolve several olfactory mechanisms for finding their hosts and avoiding unsuitable hosts and nonhost species. NHV and unsuitable host signals have potential for use in protecting trees from attack. The use of these signals may be facilitated by the fact that their combination has an active inhibition radius of several metres in trap test, and by the observation of area effects for several trees near inhibitor soruces in tree protection experiments. Furthermore, incorporation of negative signals (such as NHV and verbenone) and pheromone‐based mass‐trapping in a ‘push–pull’ fashion may significantly increase the options for control against outbreaks of conifer‐inhabiting bark beetles, especially in high risk areas.     

Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum

1 Sudden oak death is caused by the apparently introduced oomycete, Phytophthora ramorum. We investigated the role of bark and ambrosia beetles in disease progression in coast live oaks Quercus agrifolia. 2 In two Marin County, California sites, 80 trees were inoculated in July 2002 with P. ramorum and 40 were wounded without inoculation. Half of the trees in each group were sprayed with the insecticide permethrin [cyclopropanecarboxylic acid, 3‐(2,2‐dichloroethenyl)‐2,2‐dimethyl‐(3‐phenoxyphenyl) methyl ester] to prevent ambrosia and bark beetle attacks, and then were sprayed twice per year thereafter. After each treatment, sticky traps were placed on only the permethrin‐treated trees. Beetles were collected periodically in 2003. 3 Inoculated trees accounted for 95% of all beetles trapped. The ambrosia beetles Monarthrum scutellare and Xyleborinus saxeseni and the western oak bark beetle Pseudopityophthorus pubipennis were the most abundant of the seven species trapped. 4 Permethrin treatment delayed initiation of beetle attacks and significantly reduced the mean number of attacks per tree. Beetles did not attack any wounded or noncankered inoculated trees. 5 Trees with larger cankers trapped more beetles early in the disease. Once permethrin lost effectiveness, the number of beetle entrance tunnels was a more reliable predictor of subsequent trap catch than was canker size. 6 Beetles were initially attracted to P. ramorum cankers in response to kairomones generated in the host‐pathogen interaction. After beetles attacked the permethrin‐treated trees, aggregation pheromones most probably were the principal factor in beetle colonization behaviour.     

小蠹虫对针叶类寄主树木的选择危害机制

小蠹虫对寄主植物的选择是一个非常复杂的过程,也是近年来小蠹虫生态学研究的一个热门话题。文章对国内外小蠹虫寄主搜寻、寄主识别,以及适宜寄主选择等机制等方面的最新研究成果进行了系统报道。     

The gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer‐feeding beetles

The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta‐analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on nonconifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis‐associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or through the supplementation of essential nutrients.     

Hymenopterous parasitoids of bark beetles [Scolytidae] in Israel: Relationships between host and parasitoid size,and sex ratio

Information on parasitoids of bark beetles infesting conifers and broadleaves is presented to show the relations between host and parasitoid size, and parasitoid sex ratios. Sticky traps were employed to determine the sex ratios of parasitoid species operating on beetle-infested material. A wide range in body length was found for most species. Females ofCerocephala eccoptogasteri Masi,Cheiropachus quadrum Febr.,Eurytoma morio Boheman,Heydenia pretiosa Forster,Metacolus unifasciatus Forster,Rhaphitelus maculatus Walker andRoptrocerus xylophagorum (Ratz.) were usually significantly longer than their males, whereas the males of all fourDendrosoter spp. were significantly longer than the females. Body lengths of the males and females were almost identical inEntedon ergias Walker andEcphylus caudatus Rusch. The sex ratio varied markedly within most species; the mean ratio for 5 of them differed significantly from 1∶1. The sex ratio ofM. unifasciatus andE. morio was significantly related to host size. The sex-ratio of parasitoids trapped on sticky traps varied with time in relation to the phenology of the host beetle. Females were more numerous during the larvae development while males were more abundant between the pupal stage and emergence of the host. Male courtship behaviour ofDendrosoter caenopachoids Rusch.,D. protuberans (Nees),M. unifasciatus andR. xylophagorum is described. The effect of host size, the diversity in sex ratios, and possible interaction between parasitoid size and sex-ratio are discussed. Contribution from the Agricultural Research Organization, Bet Dagan, Israel. N° 1328-E, 1984 series.