Increasing intraspecific plant chemical diversity at plot and plant level affects herbivorous, predatory, and pollinating arthropod communities

Plant chemistry mediates interactions between plants and their environment. While intraspecific chemodiversity at the plant level is well-studied, the effects of groups of plants differing in chemistry on interactions need more attention. We conducted a field experiment to test how intraspecific chemodiversity affects plant-arthropod interactions.

We manipulated plots of Tanacetum vulgare L., differing in chemotype richness and composition, and monitored four arthropod groups (herbivores, flower visitors, predators, and ants) over three seasons. We hypothesized that higher plot-level chemotype richness enhances occurrence across all studied arthropod groups and that the effect on abundance would be negative for herbivore and ant abundance and positive for flower visitors and predators.

Our findings, as revealed by mixed models, show that with increasing plot-level chemotype richness, herbivore abundance decreased, flower visitor abundance increased, and predatory arthropods and ants remained largely unaffected.

These results underscore the role of plant chemical diversity in shaping insect communities and contributing to ecosystem dynamics.