Comparative Phloem Chemistry of Manchurian (<Emphasis Type="Italic">Fraxinus mandshurica</Emphasis>) and Two North American Ash Species (<Emphasis Type="Italic">Fraxinus americana and Fraxinus pennsylvanica</Emphasis>)

Recent studies have investigated interspecific variation in resistance of ash (Fraxinus spp.) to the exotic wood-boring beetle, emerald ash borer (EAB, Agrilus planipennis). Manchurian ash (Fraxinus mandshurica) is an Asian species that has coevolved with EAB. It experiences little EAB-induced mortality compared to North American ashes. Host phloem chemistry, both constitutive and induced, might partly explain this interspecific variation in resistance. We analyzed the constitutive phloem chemistry of three ash species: Manchurian ash and North American white (Fraxinus americana) and green (Fraxinus pennsylvanica) ash. Analysis of the crude phloem extracts revealed the presence of an array of phenolic compounds including hydroxycoumarins, a monolignol, lignans, phenylethanoids, and secoiridoids. Both qualitative and quantitative differences were observed among the three ash species. Hydroxycoumarins and the phenylethanoids, calceloariosides A and B, were present only in the phloem of Manchurian ash and might represent a mechanism of resistance against EAB.     

Distinguishing Defensive Characteristics in the Phloem of Ash Species Resistant and Susceptible to Emerald Ash Borer

We examined the extent to which three Fraxinus cultivars and a wild population that vary in their resistance to Emerald Ash Borer (EAB) could be differentiated on the basis of a suite of constitutive chemical defense traits in phloem extracts. The EAB-resistant Manchurian ash (F. mandshurica, cv. Mancana) was characterized by having a rapid rate of wound browning, a high soluble protein concentration, low trypsin inhibitor activities, and intermediate levels of peroxidase activity and total soluble phenolic concentration. The EAB-susceptible white ash (F. americana, cv. Autumn Purple) was characterized by a slow wound browning rate and low levels of peroxidase activity and total soluble phenolic concentrations. An EAB-susceptible green ash cultivar (F. pennsylvanica, cv. Patmore) and a wild accession were similar to each other on the basis of several chemical defense traits, and were characterized by high activities of peroxidase and trypsin inhibitor, a high total soluble phenolic concentration, and an intermediate rate of wound browning. Lignin concentration and polyphenol oxidase activities did not differentiate resistant and susceptible species. Of 33 phenolic compounds separated by HPLC and meeting a minimum criterion for analysis, nine were unique to Manchurian ash, five were shared among all species, and four were found in North American ashes and not in the Manchurian ash. Principal components analysis revealed clear separations between Manchurian, white, and green ashes on the basis of all phenolics, as well as clear separations on the basis of quantities of phenolics that all species shared. Variation in some of these constitutive chemical defense traits may contribute to variation in resistance to EAB in these species.     

Variation in the Volatile Profiles of Black and Manchurian Ash in Relation to Emerald Ash Borer Oviposition Preferences

Emerald ash borer (EAB; Agrilus planipennis) is a devastating pest of ash (Fraxinus spp.) in its invaded range in North America. Its coevolved Asian hosts are more resistant and less preferred for oviposition than susceptible North American species. We compared EAB oviposition preferences and bark and canopy volatile organic compound (VOC) emissions of resistant Manchurian ash and susceptible black ash, and examined relationships between VOC profiles and oviposition. In the field, black ash was highly preferred for oviposition while no eggs were laid on Manchurian ash, and we found clear differences in the VOC profiles of Manchurian and black ash. We detected 78 compounds emitted from these species, including 16 compounds that elicited EAB antennal activity in prior studies. Four compounds were unique to black and 11 to Manchurian ash. Emission rates of 14 canopy and 19 bark volatiles varied among the two species, including four previously reported as antennally active. Specifically, 7-epi-sesquithujene (bark) emissions were greater from black ash, while β-caryophyllene (canopy), linalool (bark), and α-cubebene (bark) were emitted at higher rates by Manchurian ash. No relationships were found between the emission rate of any single compound or group of compounds (e.g. monoterpenes) suggesting that preference may be based on complex profile combinations. This is the first study to directly compare VOCs of black and Manchurian ash as well as the first to examine bark- and canopy-specific VOCs. The unique bark and canopy VOC profiles of these two species implicates potentially important variation in VOCs between a closely related resistant and susceptible species that provides a foundation for future studies of host preferences of EAB.     

Higher Activities of Defense-Associated Enzymes may Contribute to Greater Resistance of Manchurian Ash to Emerald Ash Borer Than A closely Related and Susceptible Congener

Emerald ash borer (EAB) is an invasive beetle native to Asia that infests and kills ash (Fraxinus spp.) in North America. Previous experiments indicated that larvae feeding on co-evolved, resistant Manchurian ash (F. mandshurica) have increased antioxidant and quinone-protective enzyme activities compared to larvae feeding on susceptible North American species. Here, we examined mechanisms of host-generated oxidative and quinone-based stress and other putative defenses in Manchurian ash and the closely related and chemically similar, but susceptible, black ash (F. nigra), with and without exogenous application of methyl jasmonate (MeJA) to induce resistance mechanisms. Peroxidase activities were 4.6–13.3 times higher in Manchurian than black ash, although both species appeared to express the same three peroxidase isozymes. Additionally, peroxidase-mediated protein cross-linking activity was stronger in Manchurian ash. Polyphenol oxidase, β-glucosidase, chitinase, and lipoxygenase activities also were greater in Manchurian ash, but only lipoxygenase activity increased with MeJA application. Phloem H₂O₂ levels were similar and were increased by MeJA application in both species. Lastly, trypsin inhibitor activity was detected in methanol and water extracts that were not allowed to oxidize, indicating the presence of phenolic-based trypsin inhibitors. However, no proteinaceous trypsin inhibitor activity was detected in either species. In response to MeJA application, Manchurian ash had higher trypsin inhibitor activity than black ash using the unoxidized water extracts, but no treatment effects were detected using methanol extracts. Based on these results we hypothesize that peroxidases, lignin polymerization, and quinone generation contribute to the greater resistance to EAB displayed by Manchurian ash.     

Differential Response in Foliar Chemistry of Three Ash Species to Emerald Ash Borer Adult Feeding

The emerald ash borer (EAB; Agrilus planipennis Fairmaire; Coleoptera: Buprestidae), is an exotic wood-boring beetle that has been threatening North American ash (Fraxinus spp.) resources since its discovery in Michigan and Ontario in 2002. In this study, we investigated the phytochemical responses of the three most common North American ash species (black, green, and white ash) in northeastern USA to EAB adult feeding. Black ash was the least responsive to EAB adult feeding in terms of the induction of volatile compounds, and levels of only two (indole and benzyl cyanide) of the 11 compounds studied increased. In green ash, levels of two [(E)-β-ocimene and indole] of the 11 volatile compounds studied were elevated, while the levels of two green leaf volatiles [hexanal and (E)-2-hexenal] decreased. White ash showed the greatest response with an increase in levels of seven of the 11 compounds studied. Qualitative differences among ash species were detected. Among the phenolic compounds detected, ligustroside was the only one detected in all three species. Oleuropein aglycone and 2 unidentified compounds were found only in black ash; coumaroylquinic acid and feruloylquinic acid were detected only in green ash; and verbascoside hexoside was detected only in white ash. EAB adult feeding did not elicit or decrease concentrations of any selected individual phenolic compounds. However, although levels of total phenolics from black and green ash foliage were not affected by EAB adult feeding, they decreased significantly in white ash. EAB adult feeding elevated chymotrypsin inhibitors in black ash. The possible ecological implications of these findings are discussed.     

Electrophysiological Response and Attraction of Emerald Ash Borer to Green Leaf Volatiles (GLVs) Emitted by Host Foliage

Green leaf volatiles (GLVs) function as host attractants, pheromone synergists, or sexual kairomones for a number of coleopteran folivores. Hence, we focused on host GLVs to determine if they were attractive to adults of the emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), which feeds on ash (Fraxinus) foliage. Eight GLVs were identified by chromatography-electroantennogram (GC) and GC-mass spectrometry in foliar headspace volatiles collected in traps containing Super-Q from white ash, Fraxinus americana, and green ash, Fraxinus pennsylvanica, trees. GLVs in the aeration extracts elicited antennal responses from both male and female adults in gas chromatography-electroantennogram detection bioassays. Male antennae were more responsive than female antennae and showed the strongest response to (Z)-3-hexenol. Six field experiments were conducted in Canada and the USA from 2004 to 2006 to evaluate the attractiveness of candidate GLVs, in various lure combinations and dosages. Field experiments demonstrated that lures containing (Z)-3-hexenol were the most effective in increasing trap catch when placed on purple traps in open areas or along the edges of woodlots containing ash. Lures with (Z)-3-hexenol were more attractive to males than females, and dosage may be a factor determining its effectiveness.     

Chemical Ecology of the Emerald Ash Borer <Emphasis Type="Italic">Agrilus planipennis</Emphasis>

The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a serious invasive pest that has caused devastating mortality of ash trees (Fraxinus sp., Oleaceae) since it was first identified in North America in 2002. Shortly after its discovery, surveys were conducted, based on the visual inspection of trees. The shortcomings of visual surveys have led to a critical research need to find an efficient survey method for detecting A. planipennis infestations. Here, we present a review of research that has led to the development of effective trapping methods for A. planipennis. Studies on the insect’s biology and behavior have led to the identification of several potential attractants as well as the design of a visually attractive trap. The ongoing challenge in developing an optimally efficient trapping methodology for A. planipennis will involve finding the best combination of variables, such as trap shape, trap color (or other visual properties), trap placement, lure components, as well as the ratios and release rates of those components.     

Interactive Influence of Leaf Age,Light Intensity,and Girdling on Green Ash Foliar Chemistry and Emerald Ash Borer Development

Biotic and abiotic environmental factors affect plant nutritional quality and defensive compounds that confer plant resistance to herbivory. Influence of leaf age, light availability, and girdling on foliar nutrition and defense of green ash (Fraxinus pennsylvanica Marsh) was examined in this study. Longevity of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), adults reared on green ash foliage subjected to these factors was assayed. Mature leaves generally were more nutritious with greater amino acids and a greater ratio of protein to non-structural carbohydrate (P:C) than young leaves, in particular when trees were grown in shade. On the other hand, mature leaves had lower amounts of trypsin and chymotrypsin inhibitors, and total phenolics compared to young leaves. Lower defense of mature leaves alone, or along with higher nutritional quality may lead to increased survival and longevity of emerald ash borer feeding on mature leaves. Sunlight reduced amino acids and P:C ratio, irrespective of leaf age and girdling, and elevated total protein of young foliage, but not protein of mature leaves. Sunlight also dramatically increased all investigated defensive compounds of young, but not mature leaves. Girdling reduced green ash foliar nutrition, especially, of young leaves grown in shade and of mature leaves grown in sun. However emerald ash borer performance did not differ when fed leaves from trees grown in sun or shade, or from girdled or control trees. One explanation is that emerald ash borer reared on lower nutritional quality food may compensate for nutrient deficiency by increasing its consumption rate. The strong interactions among leaf age, light intensity, and girdling on nutrition and defense highlight the need for caution when interpreting data without considering possible interactions.     

利用改性粉煤灰处理含酚焦化废水

采用改性粉煤灰处理焦化废水中的苯酚,找出处理焦化废水中苯酚的最佳pH值、时间、温度、吸附剂的用量。     

Proteomic Analysis of Immature Fraxinus mandshurica Cotyledon Tissues during Somatic Embryogenesis: Effects of Explant Browning on Somatic Embryogenesis

Manchurian ash (Fraxinus mandshurica Rupr.) is a valuable hardwood species in Northeast China. In cultures of F. mandshurica, somatic embryos were produced mainly on browned explants. Therefore, we studied the mechanism of explant browning and its relationship with somatic embryogenesis (SE). We used explants derived from F. mandshurica immature zygotic embryo cotyledons as materials. Proteins were extracted from browned embryogenic explants, browned non-embryogenic explants, and non-brown explants, and then separated by 2-dimensional electrophoresis. Differentially and specifically expressed proteins were analyzed by mass spectrometry to identify proteins involved in the browning of explants and SE. Some stress response and defense proteins such as chitinases, peroxidases, aspartic proteinases, and an osmotin-like protein played important roles during SE of F. mandshurica. Our results indicated that explant browning might not be caused by the accumulation and oxidation of polyphenols only, but also by some stress-related processes, which were involved in programmed cell death (PCD), and then induced SE.     

高钙粉煤灰在小石峡水电站中的应用研究

研究了高钙粉煤灰不同掺量情况下混凝土的体积安定性及高钙粉煤灰的最大掺量情况下,在不同水胶比、不同掺量情况下混凝土的力学性能及耐久性性能。研究发现：掺高钙粉煤灰混凝土的安定性可通过测定其胶凝材料的安定性来评定,掺加25%左右的高钙灰,所配制的混凝土的强度性能和体积稳定性都较好,随着水胶比的降低,掺高钙粉煤灰混凝土同龄期的抗压强度逐渐增大：掺高钙粉煤灰灰混凝土具有良好的抗渗性能及良好的抗冻性能。     

粉煤灰地聚合物力学性能影响因素研究综述

粉煤灰地聚合物是以粉煤灰为硅铝质原料制备的,具有强度高、耐高温、耐腐蚀、有效固封金属离子等优点.但它固有的脆性以及需高温养护才能快速获得高强度的特点限制了其运用范围,而以纤维作为增强材料不仅可以提高粉煤灰地聚合物的强度,还可以改善其延性和韧性.本文主要从粉煤灰原料特性、碱激发剂、养护制度和增强材料四方面入手,重点阐述了...     

粉煤灰掺量对矿渣-水泥胶砂耐磨性和强度的影响

研究了粉煤灰掺量对矿渣-水泥胶砂28 d、45 d和350 d耐磨性和强度的影响.在矿渣-水泥胶砂中掺入10%的粉煤灰后胶砂28 d、45 d和350 d耐磨性可增大也可减小,但当粉煤灰掺量≥20%时,均降低,且随粉煤灰掺量继续增加,不断降低.在矿渣-水泥胶砂中掺入10%粉煤灰后胶砂28 d、45 d强度减小,且随粉煤灰掺量继续增加,不断减小.在矿渣-水泥胶砂中掺入粉煤灰后,胶砂350 d强度可增加也可降低,取决于粉煤灰掺量和矿渣取代水泥量.随掺粉煤灰的矿渣-水泥胶砂强度增大,胶砂磨损率总体趋势减小,但并不单调减小.     

Behavioral Evidence for a Contact Sex Pheromone Component of the Emerald Ash Borer, <Emphasis Type="Italic">Agrilus Planipennis</Emphasis> Fairmaire

The cuticular hydrocarbon profiles of emerald ash borers, Agrilus planipennis, were examined to determine if there are differences in these compounds between the sexes. We also assessed feral male EAB in the field for behavioral changes based on the application of a female-specific compound to dead, solvent-washed beetles. Males in the field spent significantly more time attempting copulation with dead, pinned female beetles coated with a three-beetle-equivalent dose of 3-methyltricosane than with solvent-washed beetles or those coated in 3-methyltricosane at lower concentrations. Males in the field spent the most time investigating pinned dead, unwashed female beetles. In the laboratory, sexually mature males were presented with one of several mixtures applied in hexane to filter paper disks or to the elytra of dead female beetles first washed in solvent. Male EAB also spent more time investigating dead beetles treated with solution applications that contained 3-methyltricosane than dead beetles and filter paper disks treated with male body wash or a straight-chain hydrocarbon not found on the cuticle of EAB.     

Inter- and Intra-Specific Variation in Stem Phloem Phenolics of Paper Birch (<Emphasis Type="Italic">Betula papyrifera</Emphasis>) and European White Birch (<Emphasis Type="Italic">Betula pendula</Emphasis>)

Outbreaks of bronze birch borer (BBB) (Agrilus anxius), a wood-boring beetle endemic to North America, have been associated with widespread mortality of birch (Betula spp.). There is substantial inter- and intra-specific variation in birch resistance to BBB. Species endemic to North America, such as paper birch (B. papyrifera), have coevolved with BBB and are more resistant than European and Asian birch species, such as European white birch (B. pendula), which lack an evolutionary history with BBB. Borer larvae feed on stem phloem tissue. Therefore, in search of potential resistance mechanisms against BBB, we compared the constitutive phenolic profile of stem phloem tissue of paper birch with that of European white birch. We also analyzed intraspecific variation in phenolic composition among clones and/or half-siblings of both species. Three phenolics (coumaroylquinic acid, betuloside pentoside A, and a diarylheptanoid hexoside) were detected only in paper birch, and concentrations of six other phenolics were significantly higher in paper birch. These differences may contribute to the high resistance of paper birch to BBB relative to European white birch. There was significant intraspecific variation in four of 17 phenolics found in paper birch and in five of 14 found in European white birch, but clones and half-siblings within each species could not be distinguished by phenolic composition using multivariate analysis.     

粉煤灰对碱激发矿渣/粉煤灰体系的作用机理研究

碱激发胶凝材料是以工业固体废弃物为原料制备的一种绿色无机胶凝材料,具有良好的力学性能与耐久性能。粉煤灰因其独特的球体微观结构与其他固废微粉存在本质区别,因此粉煤灰在碱激发胶凝材料体系中的作用机理亟待研究。以矿渣与粉煤灰为原料,利用碱激发剂制备胶凝材料,并对材料进行抗压强度测试,最后采用XRD、FTIR和SEM探究碱激发矿渣/粉煤灰体系的水化反应机理,研究粉煤灰对矿渣/粉煤灰体系的作用机理。结果表明:外掺3%(质量分数)NaOH作为碱激发剂,水固比为0.4时,随粉煤灰掺量减少,抗压强度呈现先上升后下降的趋势;m(矿渣):m(粉煤灰)为4:1时,28 d抗压强度达到峰值(37.1 MPa)。粉煤灰颗粒在不同龄期形成具有不同反应程度与尺寸的嵌入式微观结构,对材料力学性能起到不利影响;但粉煤灰的活化程度随龄期延长逐渐变大,对后期强度发展有持续贡献。碱激发矿渣/粉煤灰体系水化产物中含有Friedel盐、托贝莫来石、钙矾石、C-S-H/C-A-S-H凝胶,以及粉煤灰中残留的α石英相。随粉煤灰掺量增加,托贝莫来石生成量减少,钙矾石向Friedel盐转变,钙矾石生成量减少,Friedel盐生成量增多。     

掺粉煤灰和矿粉对混凝土开裂性能的影响

选用粉煤灰、矿粉作为掺合料以单掺和复掺的形式掺入到硅酸盐水泥混凝土中,检测其坍落度和3d、28d抗压强度以及早期抗开裂性能。研究结果表明:矿粉、粉煤灰均会降低混凝土3d强度,矿粉可以提高混凝土28d强度,粉煤灰掺量过大会降低混凝土28d强度。随着矿粉掺量的增加,混凝土坍落度随之降低,粉煤灰刚加入时会使混凝土坍落度降低,但是随着掺量的升高,坍落度会逐渐增大;开裂方面:单掺时,粉煤灰与矿粉都在掺量为37%时,抗开裂效果最佳,其中粉煤灰效果最好,复掺时,随着矿粉相对掺量的变大,裂缝的面积和数目都在增大。     

Male-Produced Pheromone of <Emphasis Type="Italic">Spathius agrili</Emphasis>, A Parasitoid Introduced For The Biological Control Of The Invasive Emerald Ash Borer, <Emphasis Type="Italic">Agrilus planipennis</Emphasis>

The braconid wasp, Spathius agrili, has been released in the U.S. as a biocontrol agent for the invasive emerald ash borer (Coleoptera: Buprestidae: Agrilus planipennis), a destructive pest of ash trees (Fraxinus spp.). We identified and synthesized seven male-specific volatile compounds. Three of these, dodecanal, (4R,11E)-tetradecen-4-olide, and (Z)-10-heptadecen-2-one, were the key behaviorally active components in flight tunnel bioassays. Male specificity was demonstrated by gas chromatographic comparison of male and female volatile emissions and whole body extracts. Identifications were aided by coupled gas chromatographic-mass spectrometric (GC-MS) analysis, microchemical reactions, NMR, chiral GC analysis, and GC and MS comparison with authentic standards. Both the racemic and chiral forms of the γ-lactone, as well as both E- and Z-isomers were synthesized. Flight tunnel behavioral tests showed positive male and female S. agrili responses to both natural pheromone and synthetic blends, with upwind flight and landing on the source. Large field-cage tests, using yellow sticky traps baited with pheromone, captured approximately 50 % of the released male and female wasps in 24-h periods. The use of pheromone-baited traps in the field could simplify the current detection method for determining parasitoid establishment (i.e., laboriously felling and peeling ash trees for recovery of S. agrili from infested EAB larvae).     

粉煤灰-矿渣微粉复合双掺对水泥砂浆抗酸雨侵蚀性能的影响

研究了粉煤灰、矿渣微粉复合双掺时对水泥砂浆的强度以及抗模拟酸雨侵蚀性能的影响。通过试验发现:随着粉煤灰、矿渣微粉总掺量的不断增加,砂浆强度逐渐下降;各不同配比的砂浆经pH值为4.0的模拟酸雨干湿交替循环腐蚀后的强度变化规律为先升高后下降;与纯水泥砂浆试件相比,如粉煤灰、矿渣微粉的掺入过高,则会降低试件的强度值,但是如以强度增长率来评价砂浆的抗酸雨侵蚀能力,则各不同比例的粉煤灰、矿渣微粉复合双掺等量取代水泥配制的砂浆的强度增长率均优于同等条件下纯水泥砂浆试件,即粉煤灰、矿渣微粉复合双掺对水泥砂浆试件在模拟酸雨条件下的强度发展有改善作用。     

改性高钙粉煤灰水泥的各项性能研究

以高钙粉煤灰为原料,机械粉磨高钙粉煤灰至比表面积388.14 m2/kg,配比为50%高钙粉煤灰、45%熟料、3%石膏、1%Ca(OH)2、1%J2,制备高钙粉煤灰水泥,并对比市售普通硅酸盐水泥,通过测量计算不同龄期条件下的强度损失率、长度变化率和干缩率等参数来表征水泥各项性能.结果表明,随着龄期的增长,硅酸盐水泥的抗折、抗压强度、抗冻性及抗硫酸盐侵蚀性强度损失率和干缩率分别为8.05 MPa、56.97 MPa、45.73%、36.2%、1.8× 10-4%,而高钙粉煤灰水泥分别为8.33 MPa、58.77 MPa、37.5%、26.7%、1.5×10-4%,均优于普通硅酸盐水泥,并随龄期增长越加明显.