Alfalfa Seed Production and the Leafcutter Bee: A Pollination Partnership

The vital role of pollinators, particularly the alfalfa leafcutting bee, cannot be overstated in the context of alfalfa seed production.   

The Pollination Process

When a new experimental alfalfa variety is ready to be sold, we have to produce more seed. Alfalfa is heavily reliant on pollinators to produce seeds. When a pollinator such as a leafcutter bee visits an alfalfa flower to collect nectar or pollen, the flower is triggered and pollen is deposited onto the bee, which is then transferred to the next flower the bee visits, thereby facilitating pollination.   

Among all potential pollinators, the alfalfa leafcutting bee is notably efficient and effective in pollinating alfalfa. These bees significantly increase alfalfa seed yields where they are managed properly, compared to pollination with honeybees or the lack of a pollinator. This is largely due to their solitary nature and their specific adaptation to the conditions where alfalfa is typically grown.   

Large numbers of leafcutting bees (40,000 to 60,000 per acre) are used to pollinate an alfalfa seed crop. The timing of the bees’ emergence is carefully synchronized with the beginning of the alfalfa flower bloom. This requires expertise in both bee management and alfalfa management, reflecting the critical interdependence between the alfalfa crop and its bee pollinators.   

Challenges and Solutions in Bee Management

Yet, managing these bees is not without its challenges. They face threats from natural enemies and diseases that can impact their populations. Despite these challenges, the industry has developed methods to manage and protect these essential pollinators.

tors, ensuring the continued production of alfalfa seed. This includes precise construction of nesting boards, controlled incubation, light traps, and insecticides, as well as sourcing healthy bees from regions less affected by certain diseases, such as chalkbrood and “pollen balls”.   

Thus, alfalfa leafcutting bees are not just beneficial, but essential to the alfalfa seed industry. Their role in ensuring the development of alfalfa seed crops underscores the broader importance of pollinators in agriculture and ecosystem health. The next time you plant alfalfa seed, be sure to thank the bees! To learn more, you can check out the research done by the USDA on these pollinators.