Tree species composition rather than diversity triggers associational resistance to the pine processionary moth

摘要: Abstract The reduction of insect herbivory is one the services provided by tree diversity in forest ecosystems. While it increasingly acknowledged that compositional characteristics species assemblages play a major role triggering associational resistance to herbivores, underlying mechanisms are less well known. We addressed this question ORPHEE experiment assessing pine processionary moth infestations ( Thaumetopoea pityocampa ) across gradient from monocultures five mixtures. showed richness per se had no effect on probability attack pest. By contrast, infestation rate was strongly dependent plot composition. Mixtures pines Pinus pinaster and birches Betula pendula were prone T. infestations, whereas mixtures oaks Quercus spp.) more often attacked than monocultures. taking into account relative height associated broadleaved species, could be explained apparency. Pines average 343 ± 5 cm height. Birches, as fast growing trees, slightly taller (363 ± 6 cm), while oak trees significantly smaller (74 ± 1 cm). Host then partly hidden but apparent with oaks. suggest reduced apparency disrupted visual cues used female moths select host prior oviposition. This study highlights need take traits such growth when selecting have order improve pest insects.