D3455: Wild pollinators of alfalfa seed

Alfalfa (Medicago sativa L.) is a globally important crop that requires pollination by bees to produce optimal yield. In the United States, three bee species are commercially managed for alfalfa pollination services—honey bees (Apis mellifera L.), alfalfa leafcutting bees (Megachile rotundata Fabricius), and alkali bees (Nomia melanderi Cockerell). However, many crops benefit from a diverse pollinator community, and previous studies suggest that wild bees may also contribute to alfalfa pollination. Understanding the diversity and efficacy of wild pollinators in alfalfa is critical to developing more sustainable seed production and aligns with growers’ interest in supporting wild bees.

To document the diversity of wild pollinators, we established 14 bee bowl transects in alfalfa seed fields and sampled weekly during bloom in 2024. Then to assess the efficacy of wild bees as alfalfa pollinators, we observed individual alfalfa plants for 20 minutes and for each floral visitor, we noted whether they successfully tripped the flower. Preliminary results suggest that some wild bees are effective pollinators of alfalfa and alfalfa seed hosts a diverse community of pollinators beyond the managed species. These results show that wild bees can perform effective pollination services in alfalfa and should be considered in management plans.