Specific Attraction of Fig-Pollinating Wasps: Role of Volatile Compounds Released by Tropical Figs

Floral scents often act as pollinator attractants. In the case of obligate and specific plant–pollinator relationships, the role of floral signals may be crucial in allowing the encounter of the partners. About 750 Ficus species (Moraceae) are involved in such interactions, each with a distinct species of pollinating wasp (Chalcidoidea, Agaonidae). Several species have been shown to release volatile compounds, but their role in pollinator attraction has rarely been simultaneously tested. We investigated the floral scents of four tropical fig species and combined chemical analysis with biological tests of stimulation of insects. Pollinators of three species were stimulated by the odor of their associated fig species and generally not by the odor of another species. The fourth actually comprised two distinct varieties. The main compound was often a different one in each species. Floral blends of different species always shared compounds, but ratios of these compounds varied among species.     

炼焦过程中挥发性有机物化学反应活性的研究

利用不锈钢采样罐和全自动预浓缩/GC/MS系统,在58-Ⅱ型和JN43-80型焦炉顶测试了炼焦过程中挥发性有机物(VOCs)中各组分的浓度,结合OH自由基消耗速率分析了这些物质的反应活性。研究发现,装煤时刻产生的TVOCs浓度明显高于炼焦过程产生的;炼焦过程中(包括装煤时刻)无组织排放的VOCs反应活性各不相同。     

A Novel Approach for Isolation of Volatile Chemicals Released by Individual Leaves of a Plant in situ

A glass chamber designed specifically for collecting volatile chemicals from individual leaves of a plant in situ is described. The effectiveness of the chamber was demonstrated by collecting volatile chemicals from single leaves of two plant species, potato (Solanum tuberosum) and broad bean (Vicia faba), before and after mechanical damage. The glass chamber, in conjunction with thermal desorption, enables reduction of the entrainment time and thereby allows the monitoring of compounds released by leaf damage in successive 5-min periods. An intact broad bean leaf, in the middle of the day, produces small amounts of the green leaf volatiles (E)-2-hexenal and (Z)-3-hexen-1-ol. However, during the first 5 min after mechanical damage, large amounts of (Z)-3-hexenal, (E)-2-hexenal, and (Z)-3-hexen-1-ol are produced. The decline in production of (Z)-3-hexenal and (E)-2-hexenal is fast, and after 10 min, these compounds reach very low levels. (Z)-3-Hexen-1-ol shows an increase for the first 10 min and then a gradual decline. An intact potato leaf, in the middle of the day, produces very small amounts of the sesquiterpene hydrocarbons -caryophyllene and germacrene-D. After being damaged, the profile of released volatiles is different from that of broad bean. In potato, damage is associated with release of large amounts of green leaf volatiles and sesquiterpene hydrocarbons. Compounds such as (Z)-3-hexenal, (E)-2-hexenal, and (Z)-3-hexen-1-ol are released in high amounts during the first 5 min after damage, but after 10 min, these drop to very low levels. High release associated with damage is also observed for -caryophyllene, (E)--farnesene, germacrene-D, and -bisabolene. The highest level is reached 5 min after damage and 15 min later, these compounds drop to low levels. The significance of compounds released after plant damage is discussed.     

固相微萃取法结合GC-MS分析小鱼眼草中挥发性化合物

采用固相微萃取技术提取小鱼眼草挥发油成分,用气相色谱-质谱联用技术对挥发油成分进行分析测定。从小鱼眼草挥发油中鉴定出32个化学成分,占挥发油色谱总峰面积的97.24％。其中含量超过4％的组分有:大香叶烯-D(30.84％)、3-异丙基-5,5-二甲基-环戊烯(17.11％)、β-石竹烯(8.00％)、大香叶烯-B(5....     

Comparative Capability to Detoxify Vegetable Allelochemicals by Larval Mosquitoes

In order to confirm the phytotoxicological basis for the ecological specialization of larval culicine fauna among different subalpine mosquito breeding sites, we compared the capability of six different Aedes larval taxa or populations of different ecological origin to detoxify dietary leaf litter originating from the environmental vegetation. Detoxification experiments were performed through in vitro digestion of a toxic leaf litter fraction using larval extracts as the enzymatic sources. Comparison of toxicological and detoxifying properties among the different larval samples indicates an association between their tolerance to leaf litter toxicants and their detoxification capability, which vary according to ecological origin. The fact that the detoxifying factor within the larval extracts appears to be a protein-like compound with a molecular weight bigger than 30 kDa suggests the possible involvement of detoxifying enzymes in larval tolerance to leaf litter toxicants. This is congruent with previous biochemical data that suggests the involvement of cytochrome P450 monooxygenase and esterase activities in the detoxification process.     

Herbivorous Caterpillars and the Green Leaf Volatile (GLV) Quandary

Several herbivorous caterpillars contain effectors in their oral secretions that alter the emission of green leaf volatiles (GLVs) produced by the plants upon which the caterpillars are feeding. These effectors include an isomerase, a fatty acid dehydratase (FHD), and a heat-stable hexenal trapping (HALT) molecule. GLVs serve as signaling compounds in plant-insect interactions and inter-and intra-plant communication. However, it is not known whether these GLV-altering effectors are common among herbivorous caterpillars, or the evolutionary context of these effectors in relation to GLV emission by host plants in response to feeding damage. Here, we examined the distribution and activity of the isomerase, FHD, and HALT effectors across 10 species spanning 7 lepidopteran families. Six of the 10 species possessed all three effectors in their oral secretions. Activity from the HALT and FHD effectors was observed in all examined caterpillar species, while activity from the isomerase effector varied in some species and was absent in others. There was no discernable pattern in effector activity based on evolutionary divergence, since individual species within a family did not possess similar mechanisms to alter GLV emission. These data, demonstrating the GLV-altering effectors acting at different steps in the GLV biosynthetic pathway and present in the examined caterpillar species at different combinations with different activities, highlight the importance of these effectors in changing the emission of these compounds during caterpillar herbivory. Understanding the prevalence and roles of GLV-altering effectors and GLV emission itself will open new research areas in the dynamics of plant-insect interactions.

     

应用模拟室内环境试验箱研究涂层有机挥发物的散发性

本研究以双组分溶剂型涂料形成涂层为代表试样,应用模拟室内环境试验箱,采用一次热解吸气相色谱法测定涂层有机挥发物的散发浓度,研究不同模拟试验条件(暴露面积、温湿度、光源、通风等)对被测涂层有机挥发物的散发性影响.研究发现被测涂层有机挥发物散发浓度随暴露面积、温度、湿度的增大明显增大,使用普通蓝荧光灯或365nm的UV-A...     

Modeling of Groundwater Contamination by Phenol Released from Spilled Bitumen

Leaching of phenol from spilled bitumen into flowing aquifer poses an environmental threat to groundwater contamination. A two‐dimensional model with de‐coupled transfer was built to model phenol propagation in the flowing stream. The model predicted that the produced phenol concentration monitored at an observation well would rise sharply and then decline gradually as the phenol flux emerging from the bitumen surface was depleted with time. The model is useful in estimating the size of the spill, produced phenol concentration, phenol spatial distribution and the time required for the phenol concentration to decline to an environmentally acceptable level. It is well suited to other water pollution problems with chemical spills.     

Systemic Induction of Allelochemicals in Glanded and Glandless Isogenic Cotton by Spodoptera exigua Feeding

Induction of systemic resistance to feeding of beet armyworm, Spodoptera exigua, was investigated in two isogenic lines of Stoneville 213 cotton, Gossypium hirsutum, that differed in the presence of pigment glands. In laboratory bioassays, larvae strongly preferred to feed on glandless cotton plants when presented a choice between undamaged terminal leaves of undamaged glanded and glandless plants. Feeding damage inflicted by S. exigua larvae on the two oldest leaves of glanded plants seven days prior to feeding bioassays caused larvae to prefer by 33-fold the undamaged terminal foliage from undamaged plants compared to that from damaged plants. Feeding damage on glandless plants caused only a 2.6-fold greater preference for terminal foliage from undamaged plants over foliage from previously damaged plants. Extracts of terminal foliage from glanded cotton damaged seven days earlier had significantly greater quantities of terpenoid aldehydes (hemigossypolone, gossypol, and heliocides) than did foliage from undamaged glanded plants. Terpenoid aldehydes were undetectable in extracts of both undamaged and previously damaged glandless plants. The profile of volatile compounds collected from the headspace of mechanically damaged terminal leaves of undamaged glanded and glandless plants differed. Both cotton isolines released large quantities of lipoxygenase products (hexenyl alcohols, acetates, and butyrates), but glandless plants released only small amounts of mono- and sesquiterpenes compared to glanded plants. Glandless plants damaged seven days prior to volatile collection released significantly greater quantities of lipoxygenase products, -ocimene, and - and -farnesene than did undamaged glandless plants. Previously damaged glanded plants released significantly greater quantities of all mono- and sesquiterpenes and hexenyl acetates and butyrates, but not alcohols. The relative importance of volatile compounds versus terpenoid aldehydes in induced feeding deterrence in cotton to S. exigua larvae is still unclear.     

Production and Properties of Ejecta Released by Fracture of Materials

We have examined ejecta (particles in the size range 0.1 to 500 μm) which are released by fracture of a variety of materials. The ejecta from most non-metallic materials are electrically charged and frequently have high velocities. The amount of ejecta produced depends on the material and the conditions of fracture. For unfilled, glassy polymers the ejecta are produced in regions of fast-hackled fracture. Detailed measurements have been made on the ejecta mass and size distributions from the fracture of composites. From these measurements the total particle surface areas can be estimated and are found to be comparable to or greater than the cross-sectional area of the fractured samples. Thus, the ejecta should be a consideration in the analysis of surface energy and other parameters from fractographical analysis.     

Comparative Detoxification of Plant (Magnolia virginiana) Allelochemicals by Generalist and Specialist Saturniid Silkmoths

The foliage of sweetbay magnolia (Magnolia virginana) contains at least two biologically active phenylpropanoid compounds (magnolol and a biphenyl ether) that are toxic to a number of generalist insect herbivores. These compounds have little effect on caterpillars of the sweetbay silkmoth, C. securifera, which is a specialist on sweetbay, but they are toxic to two closely related silkmoths, C. angulifera and C. promethea. To understand the influence of phytochemistry on the evolution of host use and feeding specialization in Callosamia, the detoxification capability of C. securifera was compared with that of C. angulifera and C. promethea. Degradation of magnolol and the biphenyl ether by midgut homogenate of the sweetbay specialist was NADPH-dependent and inhibited by piperonyl butoxide, suggesting the involvement of cytochrome P-450 detoxification enzymes. Both were degraded three times faster in the specialist compared to the unadapted herbivores. Higher rates of degradation could not be induced in the polyphagous C. promethea by a mixture of magnolol and the biphenyl ether or by the P-450 inducer pentamethylbenzene, nor did activity vary significantly when larvae were reared on different host plants. Use of sweetbay by Callosamia silkmoths appears to be dependent on their ability to degrade host toxins rapidly via midgut detoxification enzymes. Moreover, the intraspecific comparisons contradict the common prediction that higher levels of cytochrome P-450 activity are found in more polyphagous species; instead, P-450 activity is more closely associated with specific chemical attributes of the herbivores' host plants.     

气相色谱/质谱法分析检测莳萝酊的挥发成分

用同时蒸馏萃取(SDE)和固相微萃取(SPME)两种方法对莳萝酊进行前处理,通过气相色谱/质谱法(GC-MS)检测了其挥发性和半挥发性成分。两种方法从莳萝酊中共检出62个化学物质,其中SDE检出47个,SPME检出41个,二者共同组分26个。莳萝酊的主要成分有γ-松油烯、对-伞花烃、枯敬醛,4-乙基-3-壬烯-5-炔、百里酚、香芹酚、3-甲基-4-异丙基苯酚等,和国内产的大茴香、小茴香、红茴香、藏茴香的成分明显不同。这些不同构成了莳萝的特征香味。烟草的加香实验表明,莳萝有增加香气,丰富烟香等作用。     

Volatile compounds produced by irradiation of butterfat

Anhydrous butterfat was irradiated at 6 megarads in a special glass reaction flask, and the headspace and total condensate samples were examined by wide-range (−180C to 125C) gas chromatography combined with mass spectrometry. The nature and amounts of volatile compounds were not greatly influenced by whether the butterfat was irradiated under oxygen or under vacuum, nor (apart fromn-alkanoic acids) by storage for 1 and 9 weeks. Carbon dioxide was produced in greatest amount. Of the remaining compounds, aliphatic hydrocarbons predominated both in number and amount. Aliphatic oxygenated compounds including carbonyl compounds were isolated in relatively small amounts. The following compounds were identified positively: C_1–13 n-alkanes; C_4–9 2-methylalkanes; C_2–14 alk-l-enes; C_2–9 alk-l-ynes; C_2–5 n-alkanoic acids; C_1–5 n-alkan-l-ols and propan-2-ol; C_2–8 n-alkanals and 2-methylbut-2-enal; C_3–5,7 alkan-2-ones; C_1–4 n-alkyl formates, vinyl and isoamyl formate, methyl acetate and methyln-hexanoate; and carbon dioxide. Visiting Scientist from Division of Dairy Research, C.S.I.R.O., Highett, Victoria, Australia.     

Characterisation of Oligosaccharides Released by Steam Explosion of Sulphur Dioxide ImpregnatedPinus Radiata

The nature of the solubilized oligosaccharides released from the softwood Plnus radiata by the steam explosion process in the presence or absence of sulphur dioxide are described in this paper. Steam explosion in the absence of sulphur dioxide (215δ, 3 min) resulted in partial solubilization of only the hemicelluloses (14.5 g of neutral sugars/100 g o.d. wood) to their respective oligomers, which ranged in degree of polymerization from 1 to at least 12. The effect of adding 2.5% sulphur dioxide to the substrate was to facilitate the removal and hydrolysis of both hemicellulose and cellulose components (29.5 g of neutral sugars/100 g o.d. wood) by acid catalysis. Steam explosion of the substrate at an elevated temperature of 248° in the presence of 2.5% sulphur dioxide, caused almost complete cellulose and hemicellulose solubilization, and subsequent degradation reflected in poor carbohydrate survival (24.7 g of neutral sugars/100 g o.d. wood). The addition of sulphur dioxide to the process results in enhanced hydrolysis of the solubilized material to mainly mono- and disaccharides. However, the acid reversion products such as isomaltose and gentiobiose are formed, although their effect on total fermentable sugar yield is very small. Under normal steam explosion conditions the acidic aldooligouronic acid hydrolysis products represent only about 6% of total soluble carbohydrate. Interestingly, some demethylation of 4–0-methyl-D-glucuronic acid residues were observed as a consequence of sulphur dioxide catalysis.     

Cuticular Hydrocarbon Trails Released by Host Larvae Lose their Kairomonal Activity for Parasitoids by Solidification

Journal of Chemical Ecology - Successful host search by parasitic wasps is often mediated by host-associated chemical cues. The ectoparasitoid Holepyris sylvanidis is known to follow chemical...     

Removing Volatile Impurities from Granules by Distillation Sweating

The physicochemical foundations of distillation sweating and the kinetics of the removal of volatile impurities from granules are considered. Expressions are suggested for estimating the separation efficiency in this combined process. Diphenyl, naphthalene and caprolactam granules have been purified. The influence of the nature of the separated components, the process conditions, and scale factors on the rate and efficiency are examined. The advantages of distillation sweating over ordinary distillation, sublimation, and fractional melting are demonstrated.     

Volatile compounds produced by copper-catalyzed oxidation of butterfat

Anhydrous butterfat treated with copper and stored under vacuum at 38C in the dark for 9 weeks yielded the C_5–8 n-alkanes, acetic acid and the C_4,5,7,9 alkan-2-ones. The same butterfat stored under oxygen for 1 week yielded the C_1,2,3,5-7 n-alkanes, the C_2,4–6,8 alk-l-enes, the C_7,8 alk-l-ynes, the C_2–6 n-alkanoic acids, ethanol, the C_2–7 n-alkanals, 3-methylbutanal and 4-methylpentanal, the C_1–4 n-alkyl formates, ethyl acetate and propionate,n-propyl acetate and propionate, and butanone. Both treatments yielded carbon dioxide. All samples including those not treated with copper yielded butane-2,3-dione. Visiting Scientist from Division of Dairy Research, C.S.I.R.O., Highett, Victoria, Australia.     

LWCC-CFA在检测水中挥发酚的应用

应用AA3型连续流动分析仪测定地表水中挥发酚,增加长光程比色池(LWCC)以降低方法检出限,达到更低的检测要求。经实验论证,在0~0.0500 mg/L范围内,线性良好(r=0.9999),检出限为0.0002 mg/L,满足地表水检测要求。相较手工分析方法大大提高分析效率,并且减轻对实验人员的危害。