Petals and leaves: quantifying the use of nest building materials by the world’s most valuable solitary bee

The alfalfa leafcutter bee (“ALCB”, Megachile rotundata) is a solitary, cavity-nesting bee native to Eurasia, managed as an agricultural pollinator of alfalfa and several other crops in North America since the 1940s (Pitts-Singer and Cane 2011). The most intensively managed and economically valuable solitary bee worldwide, it serves as a model organism for studying solitary bee biology (Pitts-Singer and Cane 2011). Understanding this species’ nesting behavior is critical to its propagation for commercial pollination services. As its common name suggests, female ALCBs construct their nests in above-ground holes using carefully clipped pieces of leaves (Pitts-Singer and Cane 2011).