Plant Origin and Other Attributes Impact Bee Forage Patterns in a Common Garden Study in Maine, United States; Part II

Non-native plant species integrate well into plant-pollinator networks in a diverse man-made flowering plant community

Urban green areas offer diverse flower resources for pollinators. Yet, the role of non-native plant species in local plant-pollinator networks is understudied. We explored the effects of plant origin, nationwide distribution, flower color and type on flower visitation by wild bees and honey bees as well as the structure of a plant-pollinator network in a botanical garden in Hungary. Honey bee preferred North American plants over Europeans; it had the highest degree and topological centrality value. The network had similar compactness with its simulated removal from the network model. The species richness and abundance of flower-visiting wild bees did not differ among the plants of different origins and flower color and type. Plant species of different origin, nationwide distribution, and flower color and type had the highest number of direct and indirect links. Our results suggest that non-native plant species can integrate well in diverse botanical gardens and wild bees can adopt these new foraging resources.

Bee Visitation on Flowers in Maine, United States, Reveals the Relative Attractiveness of Plants Through Space and Time: Part I

Bee reservoirs can be effective in agricultural and habitat restoration projects, but the relative attractiveness of plants is not fully understood. To improve plant selection with better knowledge of spatial, temporal, and competition aspects, we tested up to 90 plant subjects from 2012 to 2015 at four sites in Maine. We recognized Apis mellifera L., Bombus ternarius Say, 1837, 'Most Bombus' (except B. ternarius), 'Halictidae' and 'Other Bees' (collectively the so-called 'bee groups') on open flowers in three 1-min periods per site and day, with numerous repeated observations per plant taxon. In 14,311 observations, we recorded 17,792 bees in 61 species. Most-visited plants included Asclepias tuberosa, Borago officinalis, Clethra alnifolia cv. Hummingbird (especially by A. mellifera), Melilotus officinalis, Origanum vulgare, Rosa palustris (especially before 1400 hours), Spiraea alba var. latifolia, and taxa in the family Asteraceae. Early-flowering shrubs were visited, especially by 'Other Bees'. Bee groups each ranked plants uniquely, with some overlap, and differed in most-visited of six plant taxa that we had included in all 4 yr and sites. For 'All Bees' among 84 plant taxa, the most-visited plants were M. officinalis (June), A. tuberosa (July), and C. alnifolia (August). Indicator Species Analysis revealed low bee fidelity to host plants for all but a few plant taxa. Apis mellifera differed from native bees in plants it visited intensively, with some overlap (e.g., A. tuberosa), and was associated with increased visitation on seven plant taxa by 'Most Bombus' and B. ternarius.