title: Isoprene emission by poplar is not important for the feeding behaviour of poplar leaf beetles.
abstract: BACKGROUND
  Chrysomela populi (poplar leaf beetle) is a common herbivore in poplar plantations whose infestation causes major economic losses. Because plant volatiles act as infochemicals, we tested whether isoprene, the main volatile organic compound (VOC) produced by poplars (Populus x canescens), affects the performance of C. populi employing isoprene emitting (IE) and transgenic isoprene non-emitting (NE) plants. Our hypothesis was that isoprene is sensed and affects beetle orientation or that the lack of isoprene affects plant VOC profiles and metabolome with consequences for C. populi feeding.
  
  
  RESULTS
  Electroantennographic analysis revealed that C. populi can detect higher terpenes, but not isoprene. In accordance to the inability to detect isoprene, C. populi showed no clear preference for IE or NE poplar genotypes in the choice experiments, however, the beetles consumed a little bit less leaf mass and laid fewer eggs on NE poplar trees in field experiments. Slight differences in the profiles of volatile terpenoids between IE and NE genotypes were detected by gas chromatography - mass spectrometry. Non-targeted metabolomics analysis by Fourier Transform Ion Cyclotron Resonance Mass Spectrometer revealed genotype-, time- and herbivore feeding-dependent metabolic changes both in the infested and adjacent undamaged leaves under field conditions.
  
  
  CONCLUSIONS
  We show for the first time that C. populi is unable to sense isoprene. The detected minor differences in insect feeding in choice experiments and field bioassays may be related to the revealed changes in leaf volatile emission and metabolite composition between the IE and NE poplars. Overall our results indicate that lacking isoprene emission is of minor importance for C. populi herbivory under natural conditions, and that the lack of isoprene is not expected to change the economic losses in poplar plantations caused by C. populi infestation.
authors.affiliation: Büsgen Institute, Forest Botany and Tree Physiology, University of Göttingen, Büsgenweg 2, 37077, Göttingen, Germany. anna.mueller@forst.uni-goettingen.de.
authors.forename: Anna
authors.initials: A
authors.lastname: Müller
authors.affiliation: Research Unit Environmental Simulation, Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany. moritz.kaling@helmholtz-muenchen.de.|Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, D-85764, Neuherberg, Germany. moritz.kaling@helmholtz-muenchen.de.
authors.forename: Moritz
authors.initials: M
authors.lastname: Kaling
authors.affiliation: Research Unit Environmental Simulation, Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany. Patrick1_Faubert@uqac.ca.|Département des Sciences Fondamentales, Chaire en éco-conseil, Université du Québec à Chicoutimi, 555, boul. de l'Université, Chicoutimi, Qc, G7H 2B1, Canada. Patrick1_Faubert@uqac.ca.
authors.forename: Patrick
authors.initials: P
authors.lastname: Faubert
authors.affiliation: Mathematical and Statistical Methods Group, Wageningen University, P.O. Box 100, 6700 AC, Wageningen, Netherlands. gerrit.gort@wur.nl.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Gort
authors.affiliation: Laboratory of Entomology, Wageningen University, P.O. Box 8031, NL-6700 EH, Wageningen, Netherlands. hansm.smid@wur.nl.
authors.forename: Hans M
authors.initials: HM
authors.lastname: Smid
authors.affiliation: Laboratory of Entomology, Wageningen University, P.O. Box 8031, NL-6700 EH, Wageningen, Netherlands. joop.vanloon@wur.nl.
authors.forename: Joop J A
authors.initials: JJ
authors.lastname: Van Loon
authors.affiliation: Laboratory of Entomology, Wageningen University, P.O. Box 8031, NL-6700 EH, Wageningen, Netherlands. marcel.dicke@wur.nl.
authors.forename: Marcel
authors.initials: M
authors.lastname: Dicke
authors.affiliation: Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, D-85764, Neuherberg, Germany. basem.kanawati@helmholtz-muenchen.de.
authors.forename: Basem
authors.initials: B
authors.lastname: Kanawati
authors.affiliation: Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, D-85764, Neuherberg, Germany. schmitt-kopplin@helmholtz-muenchen.de.
authors.forename: Philippe
authors.initials: P
authors.lastname: Schmitt-Kopplin
authors.affiliation: Büsgen Institute, Forest Botany and Tree Physiology, University of Göttingen, Büsgenweg 2, 37077, Göttingen, Germany. apolle@gwdg.de.
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.affiliation: Research Unit Environmental Simulation, Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany. jp.schnitzler@helmholtz-muenchen.de.
authors.forename: Jörg-Peter
authors.initials: JP
authors.lastname: Schnitzler
authors.affiliation: Research Unit Environmental Simulation, Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany. maaria.rosenkranz@helmholtz-muenchen.de.
authors.forename: Maaria
authors.initials: M
authors.lastname: Rosenkranz
mesh_terms: D000818:Animals; D018533:Biomass; D002070:Butadienes / Q000378:metabolism*; D002633:Chemotaxis; D001517:Coleoptera / Q000502:physiology*; D005260:Female; D020387:Food Chain; D016468:Forestry; D045782:Hemiterpenes / Q000378:metabolism*; D060434:Herbivory; D008297:Male; D055442:Metabolome; D010420:Pentanes / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000235:genetics / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000378:metabolism
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; D055549:Volatile Organic Compounds; C005059:isoprene