Single-visit effectiveness and controlled honey bee visit experiments
To assess the relative quality of honey bee visits and their direct contribution to C. quamash pollination, we performed two field experiments. In 2019, we conducted a controlled multiple-visit experiment to isolate the direct relationship between increasing honey bee visits and C. quamash pollination in one of the meadows where hives were introduced. In 2020, we returned to a different meadow, where honey bee abundance was more moderate, and assessed the single-visit pollination effectiveness of honey bees and other insect visitors. In both years, we bagged a selection of plants to prevent visitation and conducted observations from 7:00 until 16:00 across several days. For controlled honey bee visit experiments, we allowed a randomly assigned number of honey bee visits (between zero and twenty) to freshly opened flowers and all other visitors were excluded. For single-visit effectiveness experiments, we allowed a single visit from different visitors, noting the pollinator identity and aspects of its visit behavior (described in Table S1). Because we did not want to impact an insect’s visit by capturing it, our identifications were done in the field. We grouped visitors into several broad categories: Andrenaspp., Apis mellifera , Bombus spp., Halictus spp.Osmia spp., “Small dark bees”, and Syrphid flies. For both field experiments, we re-bagged plants to prevent further visitation after experimental visits had concluded, collected fruits two weeks later, and counted fertilized ovules.