Attraction of the grasshopper, Melanoplus sanguinipes, to host plant odors and volatile components

The attraction of the polyphagous grasshopper, Melanoplus sanguinipes (F.), to odors from plant foliage or to chemical components of these odors was tested in a glass Y-tube olfactometer. Humidified air was passed at equal flow rates through a sample chamber containing plant material and an empty control chamber and then through the Y-tube to the holding chamber containing the test insect. Solutions of volatile chemicals in water were metered at a constant rate into the sample air stream with a syringe pump. Insects moving upwind were recorded after entering either the sample or control arm of the Y-tube. Both nymphs and adults were strongly attracted to the odor of chopped and intact seedling foliage of perennial ryegrass and wheat. Chopped leaves but not intact leaves of sorghum and alfalfa also were significantly attractive. The major components of ryegrass odor from both chopped and stem-cut leaves were Z-hex-3-en-1-yl acetate, Z-hex-3-en-1-ol, and pent-1-en-3-ol, in that order, with lesser amounts of E-hex-2-enal. Chopped leaves released many more minor components. The major components when tested individually or in binary and ternary mixtures were significantly attractive to grasshoppers compared to humidified air but not to the degree of whole plant odor. However, a quartenary mixture simulating the odor blend had levels of attractancy equal to that of chopped grass odor. Blends of these 5- and 6-carbon unsaturated alcohols, esters, and aldehydes volatilizing from green plants probably play an important role as olfactory cues for orientation of grasshoppers to food plants.

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Résumé L'attraction de M. sanguinipes (F.) par l'odeur du feuillage et des composés chimiques de ces odeurs a été examinée dans un olfactomètre en tube de verre en Y. Des flux identiques d'air humidifié étaient introduits dans une enceinte contenant le matériel végétal et dans une enceinte témoin, et, via le tube en Y, dans l'enceinte contenant l'insecte à étudier. Des solutions aqueuses de substances volatiles étaient introduites à un taux constant dans le courant d'air grâce à une seringue. Les insectes se déplaçant contre le vent étaient enregistrés après pénétration dans une branche déterminée du tube en Y. Larves et adultes étaient fortement attirés par l'odeur de feuillage intact ou coupé de semis de Lolium perenne et de blé (Triticum aestivum). Les feuilles coupées, mais non les feuilles intactes de sorgho (Sorghum bicolor) et de luzerne (Medicago sativa) étaient, elles aussi, significativement attractives. Les principales substances constituant de l'odeur de feuilles de Lolium perenne, tant coupées qu'intactes, étaient dans l'ordre de Z-hex-3-en-1-yl acétate, le Z-hex-3-en-1-ol et le pent-1-en-3-ol, et dans une moindre mesure, E-hex-2-enal. Les feuilles coupées libéraient beaucoup plus de composés secondaires. Les principaux constituants testés, seuls ou en mélanges binaires ou ternaires, étaient significativement attractifs, mais moins que l'odeur totale de la plante. Toutefois, un mélange quaternaire, simulant le mélange odorant, avait le même pouvoir attractif que l'odeur de la plante entière. L'union de ces alcools, esters et aldéhydes à 5- et 6-carbones non saturés, volatilisés à partir des plantes vertes, jouent probablement un grand rôle comme signaux orientateurs lors de l'attraction des criquets par leur plantes alimentaires.

     

Influence of the inoculation time of high sugar content must on the formation of wine aroma

The addition of inocula of a commercially available strain of Saccharomyces cerevisiae to musts with a high initial sugar content at various fermentation stages induces variable changes in the different components of the volatile fraction of wine and, potentially, its sensory properties as well. Inoculation alters the concentration ratio between the 2,3-butanediol isomers and causes a decrease in acetates and ethyl ester content. We propose an analytical ratio to evaluate the aromatic quality of the wine.     

Olfactory responses recorded from sensilla coeloconica of the silkmoth Bombyx mori

Abstract. Extracellular single sensillum recordings were made from the double-walled multiporous sensilla coeloconica on the antennae of males and females of Bombyx mori L. (Lepidoptera: Bombycidae). The receptor neurones responded to olfactory stimuli; no thermo- or hygroreceptors were found. Many neurones responded with a decrease of the transepithelial potential and increased rates of nerve impulses to aliphatic hydrocarbons with chain lengths between three and ten carbon atoms. Most abundant were neurones responding best to acids and aldehydes. Receptor neurones responding with a low threshold to only one acid of a certain chain length were considered as specialists. In some sensilla an increase of the transepithelial potential combined with nerve impulse inhibition was observed in response to monoterpene alcohols. Neurones responding with excitation to aliphatic acids and with inhibition to terpenes were found in the same sensilla. Some neurones excited by aliphatic acids were inhibited by terpenes. Responses to headspace volatiles of mulberry leaves, the larval food, were also obtained. Therefore the coeloconic sensilla may be involved in the selection of oviposition sites.     

烟草挥发物对2近缘种夜蛾产卵行为的影响及其成分分析

寡食性烟夜蛾Helicoverpa assulta (Guenée)和广食性棉铃虫H.armigera (Hübner)是铃夜蛾属2近缘种,烟草是其共同寄主.室内实验测定了1个普通烟草品种和4个黄花烟草品种叶片挥发物对二者电生理和行为反应的影响.结果表明,烟夜蛾处女雌蛾和交配雌蛾对4个黄花烟草品种叶片挥发物的EAG反应均显著高于普通烟草,而棉铃虫对普通烟草叶片挥发物的反应显著高于黄花烟草;二者的行为反应与EAG测试结果相似,黄花烟草叶片挥发物对烟夜蛾有较强的引诱作用,棉铃虫对普通烟草叶片挥发物有较强趋性;两种夜蛾雄蛾对这些挥发物的EAG和行为反应均没有雌蛾强烈,性别差异显著;GC-MS分析表明,与K326相比,马合烟叶片挥发物中尼古丁的相对含量高(76.91%),绿叶气味种类多但芳香族化合物种类少,挥发物种类和含量的不同是否与两种夜蛾产卵趋性差异相关,有待进一步研究.     

Headspace-SPME of <Emphasis Type="Italic">in vitro</Emphasis> shoot-cultures and micropropagated plants of <Emphasis Type="Italic">Lavandula viridis</Emphasis>

In this work the volatiles emitted from in vitro shoot-cultures and micropropagated plants of Lavandula viridis L’Hér. were characterized and compared with those obtained from the field-grown mother-plant, using headspace solid phase micro-extraction following by capillary gas chromatography coupled to mass spectrometry (HS-SPME-GC/MS). The headspace composition consisted mainly in oxygenated monoterpenes (66.7–79.2 %), where the major constituents emitted by the mature field-grown mother-plant, in vitro shoot-cultures and micropropagated plants were 1,8-cineole (74.0, 51.9 and 57.8 %) and camphor (2.9, 15.3 and 8.7 %), respectively. The headspace of in vitro shoot-cultures and micropropagated plants showed greater amount of α-pinene, camphene, β-pinene, β-selinene and selina-3,7(11)-diene, when compared with the field-grown mother-plant.     

植物挥发性物质在蚜虫寄主定位中的作用

本文综述了植物挥发性物质的化学性质、研究方法及其在蚜虫寄主定位中的作用     

寄主植物挥发物对梨小食心虫受孕雌虫的引诱作用初探

梨小食心虫Grapholita molesta(Busck),是一种世界性的蛀果害虫。利用产卵选择试验研究了15种寄主植物挥发物对梨小食心虫受孕雌虫的产卵引诱活性。室内试验表明:受孕雌虫对不同挥发物的产卵选择趋性不同,其中对叶醇和己酸丁酯表现出明显的产卵选择趋性。为验证寄主挥发物对受孕雌虫的实际诱捕效果,进行了田间诱捕试验。结果发现,挥发物中己酸丁酯、苯甲腈、叶醇、E-2-己烯醛以及乙酸己酯诱捕到的雌虫均为受孕雌虫,显著高于空白对照及其他物质,其中己酸丁酯的平均诱捕量最多,苯甲腈次之,E-2-己烯醛、乙酸己酯这两种物质的平均诱捕量分别为第三、第四,叶醇的诱捕量低于乙酸己酯,其余物质的诱捕量均较低。综合室内及田间试验结果发现,寄主植物挥发物对受孕雌虫的引诱作用也随它们之间的作用距离表现出一定的差异性。