Alfalfa Leafcutting Bee, Megachile rotundata (Hymenoptera: Megachilidae)

The alfalfa leafcutting bee, Megachile rotundata Fabricius (Hymenoptera: Megachilidae), has been successfully semi-domesticated within the last 50 years to pollinate alfalfa for seed production in North America. Honey bees are inefficient pollinators of alfalfa and, although bumbles bees and some other wild bees are efficient pollinators, they have proved difficult to manage. The use of the alfalfa leafcutting bee has succeeded in greatly increasing the seed yield of alfalfa. In western Canada, the average alfalfa seed yield using this bee exceeds 300 kg/ha, whereas without it is usually less than 50 kg/ha. The genus Megachile contains many species that nest in tunnels in dead trees or fallen logs. Most are solitary, but M. rotundata is gregarious and, although each female constructs and provisions her own tunnel, she will tolerate close neighbors. This behavioral characteristic is one of the main reasons why this species has been amenable to management on a commercial scale. M....