title: Contrasting responses of silver birch VOC emissions to short- and long-term herbivory.
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.
authors.affiliation: Department of Environmental Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio Campus, Finland.
authors.forename: Mengistu M
authors.initials: MM
authors.lastname: Maja
authors.forename: Anne
authors.initials: A
authors.lastname: Kasurinen
authors.forename: Pasi
authors.initials: P
authors.lastname: Yli-Pirilä
authors.forename: Jorma
authors.initials: J
authors.lastname: Joutsensaari
authors.forename: Tero
authors.initials: T
authors.lastname: Klemola
authors.forename: Toini
authors.initials: T
authors.lastname: Holopainen
authors.forename: Jarmo K
authors.initials: JK
authors.lastname: Holopainen
mesh_terms: D029662:Betula / Q000235:genetics / Q000502:physiology*; D060434:Herbivory / Q000502:physiology*; D016014:Linear Models; D024301:Plant Bark / Q000502:physiology; D018515:Plant Leaves / Q000502:physiology; D025341:Principal Component Analysis; D013729:Terpenes / Q000032:analysis; D013997:Time Factors; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D013729:Terpenes; D055549:Volatile Organic Compounds
keywords: bark herbivory; foliage herbivory; genotype; geometrid moth; pine weevil; proton-transfer mass spectrometry; volatile organic compounds