Ecological Importance of Cyanogenesis and Extrafloral Nectar in Invasive English Laurel,Prunus laurocerasus

Abstract

Abstract English laurel (Rosaceae: Prunus laurocerasus L.) is an evergreen shrub to small tree that is native to Asia but widely used in landscaping in temperate zones. In the Pacific Northwest this plant has become an important invasive species. However, surprisingly little is known about its ecology—in particular, its chemical defenses and interaction with herbivores and organisms of higher trophic levels. In the present field study, we quantitatively measured cyanogenesis (a constitutive direct chemical defense) and secretion of extrafloral nectar (EFN; an inducible indirect defense), and analyzed the effects of these defenses on insect herbivores (black vine weevil [Otiorhynchus sulcatus]) and predators (sugar ants [Tapinoma sessile]). To induce EFN production, English laurel leaves were mechanically damaged at different intensities and in a way to mimic feeding damage by the black vine weevil, which represents the only observed insect herbivore feeding on this plant at our study site near Portland, O...