The Alfalfa Leafcutting Bee, Megachile rotundata: The World’s Most Intensively Managed Solitary Bee ∗ Theresa L. Pitts-Singer and James H. Cane USDA ARS Bee Biology & Systematics Laboratory, Utah State University, Logan, Utah 84322; email: Theresa.Pitts-Singer@ars.usda.gov, Jim.Cane@ars.usda.gov Annu. Rev. Entomol. 2011. 56:221–37 First published online as a Review in Advance on August 30, 2010 The Annual Review of Entomology is online at ento.annualreviews.org This article’s doi: 10.1146/annurev-ento-120709-144836 Copyright c  2011 by Annual Reviews. All rights reserved 0066-4170/11/0107-0221$20.00 ∗ This is a work of the U.S. Government and is not subject to copyright protection in the United States. Key Words Apoidea, bivoltinism, chalkbrood, Fabaceae, pollination, Megachilidae Abstract The alfalfa leafcutting bee (ALCB), Megachile rotundata F. (Megachildae), was accidentally introduced into the United States by the 1940s. Nest management of this Eurasian nonsocial pollinator transformed the alfalfa seed industry in North America, tripling seed production. The most common ALCB management practice is the loose cell system, in which cocooned bees are removed from nesting cavities for cleaning and storage. Traits of ALCBs that favored their commercialization include gregarious nesting; use of leaves for lining nests; ready acceptance of affordable, mass-produced nesting materials; alfalfa pollination efficacy; and emergence synchrony with alfalfa bloom. The ALCB became a commercial success because much of its natural history was understood, targeted research was pursued, and producer ingenuity was encouraged. The ALCB presents a model system for commercializing other solitary bees and for advancing new testable hypotheses in diverse biological disciplines. 221 Annu. Rev. Entomol. 2011.56:221-237. Downloaded from www.annualreviews.org by U.S. Department of Agriculture on 02/07/11. For personal use only.