title: Variation in plant defences among populations of a range-expanding plant: consequences for trophic interactions.
abstract: Although plant-herbivore-enemy interactions have been studied extensively in cross-continental plant invasions, little is known about intra-continental range expanders, despite their rapid spread globally. Using an ecological and metabolomics approach, we compared the insect performance of a generalist and specialist herbivore and a parasitoid, as well as plant defence traits, among native, exotic invasive and exotic non-invasive populations of the Turkish rocket, Bunias orientalis, a range-expanding species across parts of Eurasia. In the glasshouse, the generalist herbivore, Mamestra brassicae, and its parasitoid, Microplitis mediator, performed better on non-native than on native plant populations. Insect performance did not differ between the two non-native origins. By contrast, the specialist herbivore, Pieris brassicae, developed poorly on all populations. Differences in trichome densities and in the metabolome, particularly in the family-specific secondary metabolites (i.e. glucosinolates), may explain population-related variation in the performance of the generalist herbivore and its parasitoid. Total glucosinolate concentrations were significantly induced by herbivory, particularly in native populations. Native populations of B. orientalis are generally better defended than non-native populations. The role of insect herbivores and dietary specialization as a selection force on defence traits in the range-expanding B. orientalis is discussed.
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), PO Box 50, 6700 AB, Wageningen, the Netherlands.
authors.forename: Taiadjana M
authors.initials: TM
authors.lastname: Fortuna
authors.forename: Silvia
authors.initials: S
authors.lastname: Eckert
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Harvey
authors.forename: Louise E M
authors.initials: LE
authors.lastname: Vet
authors.forename: Caroline
authors.initials: C
authors.lastname: Müller
authors.forename: Rieta
authors.initials: R
authors.lastname: Gols
mesh_terms: D000818:Animals; D019607:Brassicaceae / Q000502:physiology*; D002080:Butterflies; D017753:Ecosystem; D005247:Feeding Behavior; D005961:Glucosinolates / Q000378:metabolism; D060434:Herbivory / Q000502:physiology*; D006927:Hymenoptera; D058865:Introduced Species; D007814:Larva; D009036:Moths / Q000469:parasitology; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D057685:Plant Weeds / Q000502:physiology
chemical_list: D005961:Glucosinolates
keywords: Bunias orientalis; biogeographical approach; glucosinolates; metabolomics; plant defence traits; plant invasion; trichomes; tritrophic interactions