Reduced Seedling Production Does Not Decrease Pollinator Visitation among Buddleja Cultivars1

Butterfly bush are commonly grown for their ease of culture and attraction of pollinators. Due to their prolific seed production, many have escaped cultivation to become weedy. Breeders have developed and introduced low fertility cultivars that alleviate the threat of invasion but there is no data on how this may impact pollinator attraction. We studied 34 cultivars in a field setting of the Willamette Valley of Oregon and did not observe a relationship between female fertility, determined by seedlings produced, and pollinator visitation. Nor did we find that nectar or pollen were predictive of pollinator visitation. There was a positive correlation between pollinator visitation (all pollinators as well as when limited to native pollinators) and inflorescence count during both years of the study. During 2021 we observed a positive correlation between days in full flower and pollinator visitation including all pollinators (native pollinators and honeybees) as well as when limited to native pollinators. This study demonstrated that breeding for low fertility does not reduce pollinator visitation in butterfly bush. There are varied options of low fertility cultivars that that will also attract and provide resources for pollinators. Species used in this study: Buddleja davidii Franch, Buddleja × weyeriana .