Potential utility and research needs for the sunflower leafcutting bee, Megachile pugnata, as a managed pollinator: Short title: Sunflower leafcutting bee as a managed pollinator.

Though cultivated sunflowers have been bred to self-pollinate, the crop still has substantial reliance on pollinators, especially for the production of hybrid seed. In North America, both managed (Apis mellifera) and wild bees pollinate sunflowers, but the sunflower leafcutting bee, Megachile pugnata, has been a species of focus for domestication as a sunflower pollinator. Research suggests M. pugnata is an efficient pollinator of sunflowers, accepts artificial nests, and can be stored and released as needed for sunflower bloom. It is unclear whether M. pugnata also could serve as a pollinator for other cultivated Asteraceae. Temperature management during adult emergence, nesting, overwintering, and post-diapause periods needs investigation, as high or low temperatures can result in significant M. pugnata population losses. The choice of nesting substrate and related handling of bees (cells) also are key concerns for efficiency; because M. pugnata in cells are only protected by a cocoon (i.e., without a leaf-lined envelope), it is unclear whether mechanical processing of nests is possible. Despite apparent challenges in managing a new crop pollinator, experience in research and management of other cavity-nesting bees (e.g., Megachile rotundata and Osmia spp.) can inform efforts to address knowledge gaps that could make large-scale use of M. pugnata more feasible.