Neighborhood effects determine plant-herbivore interactions below ground

1. Plant neighbors can strongly influence the interactions between herbivores and focal plants, for instance by providing food of different quality (consumptive effects) or by changing the behavior and metabolism of the herbivore and the focal plant without being consumed (non-consumptive effects). Determining the species-specific contributions of consumptive and non-consumptive effects is important to understand the ecophysiological mechanisms which underlie neighborhood effects. 2. We quantified the impact of nine different grassland plant species on the interaction between Taraxacum officinale and the root-feeding insect Melolontha melolontha. We investigated the contribution of consumptive and non-consumptive effects to the observed patterns, and evaluated the impact of neighboring plants on the growth and physiology of T. officinale upon M. melolontha attack. 3. Melolontha melolontha growth was strongly affected by the presence of different neighboring species. The three grass spe...