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Volatile Emissions (volatile + emission)

Distribution by Scientific Domains

Chemistry	85%

Selected Abstracts

The piercing-sucking herbivores Lygus hesperus and Nezara viridula induce volatile emissions in plants ,,

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2005
Livy Williams III
Abstract Plant volatiles induced by herbivory are often used as olfactory cues by foraging herbivores and their natural enemies, and thus have potential for control of agricultural pests. Compared to chewing insects and mites, little is known about plant volatile production following herbivory by insects with piercing-sucking mouthparts. Here, we studied factors (insect life stage, gender, the role of salivary glands, and type of bioassay used for volatile induction) that influence the induction of plant volatiles by two agriculturally important hemipterans, Lygus hesperus and Nezara viridula. Feeding on intact cotton by virgin females of L. hesperus induced 2.6-fold greater volatile response compared to that induced by mated females, possibly due to increased feeding activity by virgin females. This plant volatile response was associated with elicitors present in the insect's salivary glands as well as to the degree of mechanical injury. Feeding injury by N. viridula females also increased volatile emissions in intact maize by approximately 2-fold compared to control plants. Maize seedlings injured by N. viridula emitted higher amounts of the monoterpene linalool, the sesquiterpenes (E)-,-caryophyllene, ,- trans -bergamotene, and (E,E)-,-farnesene, and the homoterpene (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, but not amounts of green leaf volatiles, compared to uninjured plants. Emissions from intact maize injured by adult males were lower than those emitted by adult females of the same age and did not differ from those emitted by uninjured plants. Similarly, feeding by virgin female N. viridula followed by excision led to 64% higher quantities of volatiles compared to untreated plants. Volatile emission in excised plants, however, was considerably greater than in intact plants, suggesting that careful consideration must be given to bioassay design in studies of herbivore-induced plant volatiles. Salivary gland extracts of N. viridula led to sesquiterpene emissions approximately 2.5-fold higher than for controls, although no significant differences were observed for green leaf volatiles, monoterpenes, and homoterpenes. These results indicate that L. hesperus and female N. viridula feeding induce volatile production in plants, and that volatile production is affected by gender and life stage of the bug. Although oviposition and mechanical injury by stylets may increase release of volatiles, elicitors from salivary glands of L. hesperus and N. viridula also seem to play a role in the emission of plant volatiles. Arch. Insect Biochem. Physiol. 58:84,96, 2005. Published 2005 Wiley-Liss, Inc. [source]

Why are seed cones of Swiss stone pine (Pinus cembra) not attacked by the specialized pine cone weevil, Pissodes validirostris?

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2001
A case of host selection vs. host suitability
Abstract The pine cone weevil, Pissodes validirostris Gyll. (Coleoptera: Curculionidae), attacks seed cones of most Eurasian pine species, except these of Swiss stone pine (Pinus cembra L.). Behavioural responses of adult weevils to cone volatile emissions of Swiss stone pine and to those of a common host, mountain pine (Pinus uncinata Ram.), were compared in an olfactometer. Weevils were significantly attracted by the volatile blend emitted by mountain pine, but Swiss stone pine volatiles elicited an inverse response, with most weevils moving in the opposite direction to the odour source. However, the majority of second instar weevil larvae that were extracted from mountain pine cones and transferred into Swiss stone pine cones were capable of developing to the adult stage. This suggests that Swiss stone pine cones do not contain strong feeding deterrents that could prevent larval development. The possible factors involved in the absence of colonization of Swiss stone pine cones by cone weevils are discussed. [source]

Comparison of volatile emissions and structural changes of melt reprocessed polypropylene resins

ADVANCES IN POLYMER TECHNOLOGY, Issue 4 2002
Q. Xiang
Abstract Polypropylene (PP), as a commodity recyclable thermoplastic, was studied in this research to evaluate the potential environmental impact resulting from volatile organic compounds (VOCs) emitted during multiple melt reprocessing. Unstabilized PP (U-PP) and stabilized PP (S-PP) resins, simulating recycled materials prone to degradation, were evaluated for total VOC emissions generated during multiple melt reprocessing by injection molding and extrusion, respectively. Results show that the maximum amount of total VOCs from each cycle (up to six cycles for extrusion and up to ten for injection molding) did not significantly change, while the cumulative VOCs increased with increasing processing cycle for both materials. A good correlation between cumulative VOC increases and melt flow index increase for the U-PP and weight-average molecular weight Mw decrease for the S-PP were obtained. Reprocessing in all cases was accompanied by decreases in Mw and melt viscosity as a result of thermooxidative degradation. FTIR data considering increases in carbonyl content and degree of unsaturation suggest that at equivalent cycle numbers, degradation appears to be more severe for the extruded material in spite of the longer oxidative induction time of the "as received" pellets used in extrusion. The onset and type of structural changes are shown to depend on cycle number and reprocessing method. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 235,242, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10027 [source]

Effect of temperature, organic amendment rate and moisture content on the degradation of 1,3-dichloropropene in soil,

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2001
Robert S Dungan
Abstract 1,3-Dichloropropene (1,3-D), which consists of two isomers, (Z)- and (E)-1,3-D, is considered to be a viable alternative to methyl bromide, but atmospheric emission of 1,3-D is often associated with deterioration of air quality. To minimize environmental impacts of 1,3-D, emission control strategies are in need of investigation. One approach to reduce 1,3-D emissions is to accelerate its degradation by incorporating organic amendments into the soil surface. In this study, we investigated the ability of four organic amendments to enhance the rate of degradation of (Z)- and (E)-1,3-D in a sandy loam soil. Degradation of (Z)- and (E)-1,3-D was well described by first-order kinetics, and rates of degradation for the two isomers were similar. Composted steer manure (SM) was the most reactive of the organic amendments tested. The half-life of both the (Z)- and (E)-isomers in unamended soil at 20,°C was 6.3 days; those in 5% SM-amended soil were 1.8 and 1.9 days, respectively. At 40,°C, the half-life of both isomers in 5% SM-amended soil was 0.5 day. Activation energy values for amended soil at 2, 5 and 10% SM were 56.5, 53.4 and 64.5,kJ,mol,1, respectively. At 20,°C, the contribution of degradation from biological mechanisms was largest in soil amended with SM, but chemical mechanisms still accounted for more than 58% of the (Z)- and (E)-1,3-D degradation. The effect of temperature and amendment rate upon degradation should be considered when describing the fate and transport of 1,3-D isomers in soil. Use of organic soil amendments appears to be a promising method to enhance fumigant degradation and reduce volatile emissions. Published in 2001 for SCI by John Wiley & Sons, Ltd [source]

Analysis of ketones by selected ion flow tube mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2003
David Smith
A selected ion flow tube mass spectrometry (SIFT-MS) study of the reactions of H3O+, NO+ and O2+. ions with the ketones (M) 2-heptanone, 2-octanone, 2-nonanone, 2-undecanone and 2-aminoacetophenone has been conducted in preparation for studies of volatile emissions from bacteria. The H3O+ reactions all proceed rapidly via exothermic proton transfer, producing only MH+ ions that form their monohydrates when water vapour is present in the helium carrier gas. The O2+. reactions proceed rapidly via dissociative charge transfer producing parent cations M+. and some fragment ions. The NO+ reactions form the NO+M adduct ions at rates which are dependent on the pressure of the helium carrier gas. Combining the present NO+ kinetic data with those available from previous SIFT studies, the phenomenon of charge transfer complexing is clearly demonstrated. This results in adduct formation in these NO+/ketone reactions at or near the collisional rate. SIFT-MS spectra are presented to illustrate the simplicity of SIFT-MS analysis of ketones using both H3O+ and NO+ precursor ions. Copyright © 2003 John Wiley & Sons, Ltd. [source]