2018 ASHS Annual Conference

There is increased interest in native plants for landscaping to support pollinators. The majority of native plants sold by nurseries are cultivars. Some consumer and conservation groups question the suitability of native cultivars (nativars) to support pollinators. This work evaluated insect pollinator visitation for five native shrub species, and one or more cultivars of each species. The following species were installed in a full sun field behind the University of Connecticut Floriculture Greenhouse Facility in a randomized complete block design with three replicates: Aronia melanocarpa, A. melanocarpa ‘UCONNAM012’ Low Scape® Rug, A. melanocarpa ‘UCONNAM165’ Low Scape® Mound, Clethra alnifolia, C. alnifolia ‘Hummingbird’, C. alnifolia ‘Ruby Spice’, Dasiphora fruticosa, D. fruticosa ‘Goldfinger’, D. fruticosa ‘Pink Beauty’, Hydrangea arborescens, H. arborescens ‘Annabelle’, Physocarpus opulifolius, and P. opulifolius ‘Monlo’ Diablo®. During the bloom period for each plant, insect visitation was measured on ten different occasions using visual observation with each observation period lasting 5 minutes. There was no significant difference in insect visitation between A. melanocarpa and its cultivars and C. alnifolia and its cultivars. Eighty percent of insect pollinators visiting Clethra species were bumblebees (Bombus sp.). Overall, D. fruticosa and its cultivar ‘Goldfinger’, both of which have yellow flowers, attracted more insects than D. fruticosa ‘Pink Beauty’, which has pink flowers. H. arborescens and P. opulifolius attracted more total insect pollinators than their respective cultivars. H. arborescens attracted 4 times as many bumblebees, 2 times as many other bees (clade Anthophila), and 2½ times as many wasps (suborder Apocrita) than did its cultivar, ‘Annabelle’. P. opulifolius attracted more honeybees (Apis mellifera) and mining bees (family Andrenidae) than its cultivar ‘Monlo’, but ‘Monlo’ attracted more hoverflies (family Syrphidae) than the straight species.