from plants to birds higher avian predation rates in trees responding to insect herbivory从植物到鸟类在树上鸟类捕食率对昆虫取食.pdfVIP

From Plants to Birds: Higher Avian Predation Rates in Trees Responding to Insect Herbivory ¨ ¨ 1 2 2 2 2 Elina Mantyla *, Giorgio A. Alessio , James D. Blande , Juha Heijari , Jarmo K. Holopainen , Toni 1 2 1 Laaksonen , Panu Piirtola , Tero Klemola 1 Section of Ecology, Department of Biology, University of Turku, Turku, Finland, 2 Department of Environmental Science, University of Kuopio, Kuopio, Finland Abstract Background: An understanding of the evolution of potential signals from plants to the predators of their herbivores may provide exciting examples of co-evolution among multiple trophic levels. Understanding the mechanism behind the attraction of predators to plants is crucial to conclusions about co-evolution. For example, insectivorous birds are attracted to herbivore-damaged trees without seeing the herbivores or the defoliated parts, but it is not known whether birds use cues from herbivore-damaged plants with a specific adaptation of plants for this purpose. Methodology: We examined whether signals from damaged trees attract avian predators in the wild and whether birds could use volatile organic compound (VOC) emissions or net photosynthesis of leaves as cues to detect herbivore-rich trees. We conducted a field experiment with mountain birches (Betula pubescens ssp. czerepanovii), their main herbivore (Epirrita autumnata) and insectivorous birds. Half of the trees had herbivore larvae defoliating trees hidden inside branch bags and half had empty bags as controls. We measured predation rate of birds towards artificial larvae on tree branches, and VOC emissions and net photosynthesis of leaves. Principal Findings and Significance: The predation rate was h