Induced defenses of Veronica spicata: Variability in herbivore-induced volatile organic compounds

•We measured induced volatile organic compounds emitted by Veronica spicata.•Melitaea cinxia feeding and oviposition induced different compounds.•Increase of terpenoids and green leaf volatiles was associated with larval feeding.•Increase of two ketones was associated with oviposition.•Oviposition also resulted in suppression of green leaf volatiles. Plants release volatile organic compounds (VOCs) that have many eco-physiological functions. Induction of plant VOCs is known to occur upon herbivory. Herbivore-induced VOCs are involved in the attraction of predators and parasitoids, a phenomenon known as an indirect defense of plants. We measured the VOC profiles of the wild species Veronica spicata with and without larval feeding and oviposition by the specialist butterfly Melitaea cinxia. V. spicata showed great plasticity when deploying indirect defences. The induction of several ubiquitous terpenoids and green leaf volatiles (GLVs) was associated with larval feeding, whereas the increase of two ketones, 6-methyl-5-hepten-2-one and t-geranylacetone and the suppression of GLVs were associated with oviposition by the butterfly.