Does the munch affect the bunch? Using community science to explore insect herbivory and fruit production in an understory plant

Digital, community‐sourced natural history records are valuable for understanding species attributes such as phenology and geographic distribution. When these records include photographs, they can also be analysed for individual phenotypes and species interactions to develop or test ecological hypotheses. Here, we use observational and experimental approaches to assess how insect herbivory affects reproductive success in a widespread forest plant, bunchberry ( Cornus canadensis ). We queried the Global Biodiversity Information Facility (GBIF) and assembled a dataset of 2578 photographic records of fruiting plants. Of these, 891 showed evidence of insect herbivory, but herbivory was not strongly associated with fruit production. In a field study we monitored 200 plants over 5 weeks. Herbivory was widespread (78% of plants showed insect feeding), but damage was generally low—only 5% of plants experienced herbivory ≥40% of total leaf area. No relationship was found between natural herbivory and fruit production. In a second field study, we simulated high herbivory by mechanically removing 40% of leaf area in early and mid‐season. Early‐season herbivory reduced fruit production by 100%, while mid‐season herbivory reduced fruit production by 87.3%. These results suggest that although high herbivory early in the season can substantially reduce fruiting, commonly observed levels of herbivory exert limited top‐down control on reproduction in bunchberry. By combining large‐scale community‐sourced records with controlled field experiments, this work demonstrates the value of mixed‐methods approaches for testing ecological hypotheses and gaining insight into the processes that shape plant–insect interactions.