As a result of co-evolution between plants and herbivores, related plants often interact with similar herbivore communities. Variation in plant-herbivore interactions is determined by variation in underlying functional traits and by ecological and stochastic processes. Hence, typically only a subset of possible interactions is realized on individual plants. We show that insect herbivore communities assembling on individual plants are structured by plant phylogeny among twelve species in two phylogenetic lineages of Brassicaceae. This community sorting to plant phylogeny was retained when splitting the community according to herbivore feeding guilds. Relative abundance of herbivores as well as the size of the community structured community dissimilarity among plant species. Importantly, the amount of intra-specific variation in realized plant-herbivore interactions is also phylogenetically structured. We argue that variability in realized interactions that is not directly structured by plant traits is ecologically relevant and must be considered in the evolution of plant defences.

Data originates from a common garden field-experiment, recording plant phenotype and herbivore communities on individual plants. Community development on plants was surveyed from 4-week-old plants until seed set. To allow the community to fully develop, insects were identified in situ to the highest taxonomic resolution possible (species or family level). The Ecology Letters manauscript has a detailed methods section that outlines data collection and methodology.

Field observations: Raw herbivore abundance observations of herbivores individual plants. Observations present cumulative abundance over all monitoring rounds (see detailed methodology in the Ecology Letters manuscript).

Phenotypic parameters: Plant height (measured from the ground to the top of the plant), diameter (measured as the distance between the two most distal leaves), length of the largest leaf, number of true leaves, and number of flowering branches. We present the maximum observed parameter values for each plant individual to represent its specific phenotype.

Phylogeny: Phylogenetic dissimilarity among 12 brassicaceous plant species, based on ITS (see detailed methodology in the Ecology Letters manuscript).