Search results for " volatiles"
showing 10 items of 28 documents
Influence of Feeding and Oviposition by Phytophagous Pentatomids on Photosynthesis of Herbaceous Plants
2010
Abstract Feeding by herbivorous insects may change photosynthetic activity of host plants. We studied how feeding and oviposition by herbivorous stink bugs, Murgantia histrionica and Nezara viridula (Heteroptera: Pentatomidae), affect photosynthetic parameters of Brassica oleracea (savoy cabbage) and Phaseolus vulgaris (French bean). First, we measured photosynthetic gas exchange, chlorophyll fluorescence imaging, and emission of induced volatile organic compounds (VOC) immediately after feeding and during a post-feeding period. Photosynthesis decreased rapidly and substantially in B. oleracea and P. vulgaris infested by feeding bugs. Stomatal conductance did not decrease proportionally wit…
Chromatographic fingerprint of the volatile fraction of rare Hedera helix honey and biomarkers identification
2018
Hedera helix (Irish ivy) honey is a very rare food product used in Ireland. The composition of the volatile fraction of this unique honey was studied for the first time using three different extraction procedures (SPE, USE and HS–SPME) and analyzed with gas chromatography and mass spectrometry. As expected, the use of combined techniques resulted in the identification of the detailed composition of honey volatiles. Identified constitutes belongs to the different chemical classes. The presence of 4(1H)-quinolinone, myrtenal and phenylacetonitrile was proposed as biomarkers of the botanical origin of ivy honey. Moreover, they are not widely widespread among honeys of different botanical origi…
Gas Leakage From Shallow Ponding Magma and Trapdoor Faulting at Sierra Negra Volcano (Isabela Island, Galápagos)
2022
We report on new volcanic gas composition results acquired in October 2017 at Minas de Azufre, a persistent fumarolic field topping the resurgent Sierra Negra caldera, in the Galápagos archipelago. Our results indicate that the Minas de Azufre fumaroles are moderately hydrous (52–64 mol.% H2O) and rich in CO2 (35–46 mol.%), with total sulfur (ST) being 21–35 times less abundant than CO2. SO2, the most abundant S species, is released at an average rate of 19 ± 9 tons/day. Using a volatile saturation model that provides the composition of magmatic gases at equilibrium with western Galápagos basaltic melt (48 wt. % SiO2) in the 400–0.1 MPa pressure range, we infer that Minas de Azufre fumaroli…
Headspace Volatile Composition of the Flowers of Caralluma europaea N.E.Br. (Apocynaceae)
2009
The volatile constituents of the flowers of Caralluma (Apteranthes) europaea (Guss.) N.E. Br. (Apocynaceae - Asclepiadoideae) from Lampedusa Island were analyzed by headspace method. The analyses allowed the identification and quantification of 41 compounds. The main components were, among the monoterpenoids, terpinolene (23.3%), a-terpinene (19.1%) and linalool (18.4%), whereas, among the carbonylic compounds the major constituents were heptanal (2.0%), octanoic acid (2.4%) and hexanoic acid (1.7%). It is worth to mention the presence of a nitrogen containing compound, indole (0.8%) and of a sulphur containing compound, dimethylsulphide (t). The compounds found in the flowers of C. europea…
Wine analysis: Study and comparison of techniques developed for the study of volatile constituents
1986
A number of headspace techniques have been compared, using a standard solution containing 12 compounds and a wine sample, viz.: (1) purge and cold trap injection; (2) dynamic headspace combined with liquidliquid extraction; (3) static headspace with and without preconcentration; (4) direct liquid injection. The sensitivity, reproducibility and speed of analysis were determined. Considering the results obtained and dependent on the purpose of the experiments and the number of samples to be examined the appropriate technique can be selected. ?? 1980 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH.
Degassing vs. eruptive styles at Mt. Etna volcano (Sicily, Italy). Part I: Volatile stocking, gas fluxing, and the shift from low-energy to highly ex…
2018
International audience; Basaltic magmas can transport and release large amounts of volatiles into the atmosphere, especially in subduction zones, where slab-derived fluids enrich the mantle wedge. Depending on magma volatile content, basaltic volcanoes thus display a wide spectrum of eruptive styles, from common Strombolian-type activity to Plinian events. Mt. Etna, in Sicily, is a typical basaltic volcano where the volatile control on such a variable activity can be investigated. Based on a melt inclusion study in products from Strombolian or lava-fountain activity to Plinian eruptions, here we show that for the same initial volatile content, different eruptive styles reflect variable dega…
Volatile contents of mafic-to-intermediate magmas at San Cristóbal volcano in Nicaragua
2017
San Cristóbal volcano in northwest Nicaragua is one of the most active basaltic–andesitic stratovolcanoes of the Central American Volcanic Arc (CAVA). Here we provide novel constraints on the volcano's magmatic plumbing system, by presenting the first direct measurements of major volatile contents in mafic-to-intermediate glass inclusions from Holocene and historic-present volcanic activity. Olivine-hosted (forsterite [Fo] < 80; Fo< 80) glass inclusions from Holocene tephra layers contain moderate amounts of H2O (0.1–3.3 wt%) and S and Cl up to 2500 μg/g, and define the mafic (basaltic) endmember component. Historic-present scoriae and tephra layers exhibit more-evolved olivines (Fo69…
Rapid shifting of a deep magmatic source at Fagradalsfjall volcano, Iceland
2022
AbstractRecent Icelandic rifting events have illuminated the roles of centralized crustal magma reservoirs and lateral magma transport1–4, important characteristics of mid-ocean ridge magmatism1,5. A consequence of such shallow crustal processing of magmas4,5 is the overprinting of signatures that trace the origin, evolution and transport of melts in the uppermost mantle and lowermost crust6,7. Here we present unique insights into processes occurring in this zone from integrated petrologic and geochemical studies of the 2021 Fagradalsfjall eruption on the Reykjanes Peninsula in Iceland. Geochemical analyses of basalts erupted during the first 50 days of the eruption, combined with associate…
Nectar-Inhabiting Bacteria Affect Olfactory Responses of an Insect Parasitoid by Altering Nectar Odors
2022
AbstractFloral nectar is ubiquitously colonized by a variety of microorganisms among which yeasts and bacteria are the most common. Microorganisms inhabiting floral nectar can alter several nectar traits, including nectar odor by producing microbial volatile organic compounds (mVOCs). Evidence showing that mVOCs can affect the foraging behavior of insect pollinators is increasing in the literature, whereas the role of mVOCs in altering the foraging behavior of third-trophic level organisms such as insect parasitoids is largely overlooked. Parasitoids are frequent visitors of flowers and are well known to feed on nectar. In this study, we isolated bacteria inhabiting floral nectar of buckwhe…
Individuazione e applicazione di composti volatili repellenti per il controllo delle popolazioni del punteruolo rosso delle palme
2014
The red palm weevil (RPW), Rhynchophorus ferrugineus Olivier (Coleoptera, Curculionidae), is one of the most severe pests of ornamental palm species in urban areas of Mediterranean countries. The cryptic nature of the weevil, and the gaps in our knowledge of its biology and ecology, hamper the development of efficient and sustainable strategies to limit its diffusion. Control strategies based on semiochemicals can be considered a suitable alternative for RPW population management, particularly in urban areas. Nevertheless these strategies might be improved by broadening our knowledge of behavior modifying stimuli suitable for adult manipulation, such as repellent chemical compounds. A first…