title: Effects of the Timing of Herbivory on Plant Defense Induction and Insect Performance in Ribwort Plantain (Plantago lanceolata L.) Depend on Plant Mycorrhizal Status.
abstract: Plants often are exposed to antagonistic and symbiotic organisms both aboveground and belowground. Interactions between above- and belowground organisms may occur either simultaneously or sequentially, and jointly can determine plant responses to future enemies. However, little is known about time-dependency of such aboveground-belowground interactions. We examined how the timing of a 24 h period of aboveground herbivory by Spodoptera exigua (1-8 d prior to later arriving conspecifics) influenced the response of Plantago lanceolata and the performance of later arriving conspecifics. We also examined whether these induced responses were modulated by the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae. The amount of leaf area consumed by later arriving herbivores decreased with time after induction by early herbivores. Mycorrhizal infection reduced the relative growth rate (RGR) of later arriving herbivores, associated with a reduction in efficiency of conversion of ingested food rather than a reduction in relative consumption rates. In non-mycorrhizal plants, leaf concentrations of the defense compound catalpol showed a linear two-fold increase during the eight days following early herbivory. By contrast, mycorrhizal plants already had elevated levels of leaf catalpol prior to their exposure to early herbivory and did not show any further increase following herbivory. These results indicate that AMF resulted in a systemic induction, rather than priming of these defenses. AMF infection significantly reduced shoot biomass of Plantago lanceolata. We conclude that plant responses to future herbivores are not only influenced by exposure to prior aboveground and belowground organisms, but also by when these prior organisms arrive and interact.
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands. m.wang@nioo.knaw.nl.
authors.forename: Minggang
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.
authors.forename: T Martijn
authors.initials: TM
authors.lastname: Bezemer
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.|Laboratory of Nematology, Wageningen University, P.O. Box 8132, 6700 ES, Wageningen, The Netherlands.
authors.forename: Wim H
authors.initials: WH
authors.lastname: van der Putten
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.
authors.forename: Arjen
authors.initials: A
authors.lastname: Biere
mesh_terms: D000818:Animals; D018533:Biomass; D055137:Glomeromycota / Q000502:physiology; D060434:Herbivory; D007814:Larva / Q000254:growth & development / Q000502:physiology; D038821:Mycorrhizae / Q000502:physiology*; D010943:Plantago / Q000382:microbiology* / Q000502:physiology*; D018411:Spodoptera / Q000254:growth & development / Q000502:physiology*; D013559:Symbiosis; D013997:Time Factors
keywords: Above-belowground interactions; Arbuscular mycorrhizal fungi; Induced defense; Iridoid glycosides; Plantago lanceolata; Timing