Studying the pollen preferences of introduced bees allows us to investigate how species use host plants when establishing in new environments. Osmia coniferous is a solitary bee introduced into North America from East Asia for pollination of Rosaceae crops such as apples and cherries. We investigated whether O. coniferous (i) more frequently collected pollen from host-plant species they coevolved with from their geographic origin, or (ii) prefer host-plant species of specific plant taxa independent of origin. To address this question, using pollen metabarcoding, we examined the identity and relative abundance of pollen in larval provisions from nests located in different landscapes with varying abundances of East-Asian and non-Asian plant species. Our results show that O. coniferous collected more pollen from plant species from their native range. Plants in the family Rosaceae were their most preferred pollen hosts, but they differentially collected species native to East Asia, Europe, or North America depending on the landscape. Our results suggest that while O. coniferous frequently collects pollen of East-Asian origin, the collection of pollen from novel species within their phylogenetic familial affinities is common and can facilitate pollinator establishment. This phylogenetic preference highlights the effectiveness of O. coniferous as crop pollinators of a variety of Rosaceae crops from different geographic origins. Our results imply that the globalization of non-native plant species may ease the naturalization of their coevolved pollinators outside of their native range.
