Real-time monitoring of herbivore induced volatile emissions in the field.

Ionicon Analytik GmbH, Technikerstrasse 21a, 6020 Innsbruck, Austria.
Physiologia Plantarum (Impact Factor: 3.26). 11/2009; 138(2):123-33. DOI: 10.1111/j.1399-3054.2009.01322.x
Source: PubMed

ABSTRACT When plants are damaged by herbivorous insects they emit a blend of volatile organic compounds (VOCs) which include a range or terpenoids and green leaf volatiles (GLVs) formed via different metabolic pathways. The precise timing of these emissions upon the onset of herbivore feeding has not been fully elucidated, and the information that is available has been mainly obtained through laboratory based studies. We investigated emissions of VOCs from Populus tremula L. xP. tremuloides Michx. during the first 20 h of feeding by Epirrita autumnata (autumnal moth) larvae in a field site. The study was conducted using Proton Transfer Reaction-Mass Spectrometry (PTR-MS) to measure emissions online, with samples collected for subsequent analysis by complementary gas chromatography-mass spectrometry for purposes of compound identification. GLV emission peaks occurred sporadically from the outset, indicating herbivore activity, while terpene emissions were induced within 16 h. We present data detailing the patterns of monoterpene (MT), GLV and sesquiterpene (SQT) emissions during the early stages of herbivore feeding showing diurnal MT and SQT emission that is correlated more with temperature than light. Peculiarities in the timing of SQT emissions prompted us to conduct a thorough characterization of the equipment used to collect VOCs and thus corroborate the accuracy of results. A laboratory based analysis of the throughput of known GLV, MT and SQT standards at different temperatures was made with PTR-MS. Enclosure temperatures of 12, 20 and 25 degrees C had little influence on the response time for dynamic measurements of a GLV or MT. However, there was a clear effect on SQT measurements. Elucidation of emission patterns in real-time is dependent upon the dynamics of cuvettes at different temperatures.

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    ABSTRACT: • Plants produce natural enemy-attracting semiochemicals known as herbivore-induced plant volatiles (HIPV) in response to herbivore damage. Deployment of synthetic HIPV in crops could enhance the biological control of pests. To test this, six HIPV [methyl salicylate (MeSA), methyl anthranilate (MeA), methyl jasmonate (MeJA), benzaldehyde (Be), cis-3-hexenyl acetate (HA), cis-hexen-1-ol (He)] in three concentrations (0.5%, 1.0% and 2.0% v/v) mixed with a vegetable oil adjuvant, Synertrol® (Organic Crop Protectants Pty Ltd, Australia), were sprayed onto winegrape, broccoli and sweet corn plants. • The relative abundance of insects within treated plots was assessed with non-attracting, transparent sticky traps at varying time intervals up to 22 days after spraying. • In the vineyard experiment, Trichogrammatidae responded to Be and MeA (0.5%) and Be (1.0%); Encyrtidae and Bethylidae responded to MeA (1.0%); Scelionidae responded to all compounds at 1.0% and 2.0%; and predatory insects responded to MeA. In sweet corn, parasitoids as a group and Encyrtidae responded to MeA (0.5%); Braconidae responded to all compounds at 0.5% and Synertrol-only; thrips responded to all compounds at 0.5% and 1.0%; while all parasitoids responded to all compounds at 0.5% and 1.0% and Synertrol-only. In broccoli, parasitoids as a group and Scelionidae responded to Be, HA, He and Synertrol-only; Trichogrammatidae responded to Be (0.5%), He (0.5% and 1.0%), MeJA (1.0%) and MeSA (0.5%); and thrips responded to all compounds at to 0.5% and 1.0%. • Significant attraction of insects occurred up to 6 days after the HIPV application, suggesting that plants may have been induced to produce endogenous volatiles that attracted insects over an extended period. • The results obtained are discussed in relation to the potential utility of synthetic HIPV to enhance the biological control of pests.
    Agricultural and Forest Entomology 02/2011; 13(1). · 1.56 Impact Factor
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    ABSTRACT: Volatile organic compounds (volatiles) comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals) both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites.
    Metabolites. 12/2011; 1(1):41-63.
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    ABSTRACT: There is a need to incorporate the effects of herbivore damage into future models of plant volatile organic compound (VOC) emissions at leaf or canopy levels. Short-term (a few seconds to 48 h) changes in shoot VOC emissions of silver birch (Betula pendula Roth) in response to feeding by geometrid moths (Erannis defoliaria Hübner) were monitored online by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS). In addition, two separate field experiments were established to study the effects of long-term foliage herbivory (FH, 30-32 days of feeding by geometrids Agriopis aurantiaria (Clerck) and E. defoliaria in two consecutive years) and bark herbivory (BH, 21 days of feeding by the pine weevil (Hylobius abietis L.) in the first year) on shoot and rhizosphere VOC emissions of three silver birch genotypes (gt14, gt15 and Hausjärvi provenance). Online monitoring of VOCs emitted from foliage damaged by geometrid larvae showed rapid bursts of green leaf volatiles (GLVs) immediately after feeding activity, whereas terpenoid emissions had a tendency to gradually increase during the monitoring period. Long-term FH caused transient increases in total monoterpene (MT) emissions from gt14 and sesquiterpene (SQT) emissions from Hausjärvi provenance, mainly in the last experimental season. In the BH experiment, genotype effects were detected, with gt14 trees having significantly higher total MT emissions compared with other genotypes. Only MTs were detected in the rhizosphere samples of both field experiments, but their emission rates were unaffected by genotype or herbivory. The results suggest that silver birch shows a rapid VOC emission response to short-term foliage herbivory, whereas the response to long-term foliage herbivory and bark herbivory is less pronounced and variable at different time points.
    Tree Physiology 03/2014; · 2.85 Impact Factor

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