Mistletoe generates non-trophic and trait-mediated indirect interactions through a shared host of herbivore consumers
Metadata
Show full item recordEditorial
Ecological Society of America
Materia
Insect herbivores Host pine Mediterranean forest Pine Processionary Pine weevil Plant–animal interaction Viscum album
Date
2019Referencia bibliográfica
L azaro-Gonz alez, A., J. A. H odar, and R. Zamora. 2019. Mistletoe generates non-trophic and trait-mediated indirect interactions through a shared host of herbivore consumers. Ecosphere 10(3):e02564
Sponsorship
This study was supported by project CLAVINOVA CGL2011-29910 to Regino Zamora from the Spanish Ministry of Science and Innovation, and FPI predoctoral grant BES-2012-057125 to Alba Lázaro- González from the Spanish Ministry of Economy and Competitiveness.Abstract
Indirect interactions emerge among a wide range of herbivores sharing the same plant
resource. Consumers usually belong to different trophic guilds, from folivores and sapsuckers to parasitic
plants. We propose that mistletoes parasitizing pines could play a key role acting as herbivores on
host pines and coming indirectly into competition with other herbivores feeding on the same host.
Changes caused by mistletoes on its host have been well studied, but its effects running across trophic
webs remain unrevealed. In this study, we investigate the effect of European mistletoe (Viscum album
subsp. austriacum) on the host-feeding herbivores via trait-mediated indirect interactions (TMIIs) across
their shared pine host (Pinus nigra subsp. salzmannii). We performed field and laboratory experiments,
and analyzed the net effect of different mistletoe parasite loads on three host-phytophagous species: the
sapsucker Cinara pini (Aphididae), the winter folivore Thaumetopoea pityocampa (Thaumetopoeidae), and
the summer folivore Brachyderes sp. (Curculionidae), all being members of different functional feeding
groups (FFGs). We summarize the mistletoe–host–herbivore interactions by means of a TMII, where
mistletoe parasitism causes non-trophic links and detrimental indirect interactions on pine-feeding herbivores
across its shared host, suggesting a worsening of host quality as food. These indirect interactions
vary according to three parameters. First, the intensity has a non-proportional relation with parasite
load, showing an impact threshold on highly parasitized pines. Second, the movement capacity of insect
herbivores determines their response, by decreasing the abundance of herbivores with low movement
ability (aphids and pine processionary caterpillars) while altering the behavior (plant selection) of more
mobile herbivores (pine weevils). Finally, FFG determines the intensity of mistletoe parasitism effects,
folivores being more responsive than sapsuckers. Overall, mistletoe generates non-trophic interaction
linkages in the forest able to modify community structure by becoming a nexus of the entire herbivore
community of the pine canopy.