OneGen - an old idea

In the American northwestern states, a high % of field-emerged second generation bees is a common observation. In the late 1970s, the USDA  Bee Biology and Systematics Laboratory at Logan, Utah, undertook a program to introduce lines of leafcutter bees from Spain. Parker and Tepedino (1982) reported that these selections had a greatly reduced second generation; thus 23% of females from the American line emerged whereas none of the Spanish females emerged during the summer season. Unfortunately these valuable lines were not maintained. In any event, the maintenance of any commercial lines from these selections would have been seriously hampered by the wild populations of Megachile rotunda found throughout the major alfalfa seed producing areas of the USA.
Parker, F.D. and Tepedino, V. J. (1982). Maternal influence on diapause in the alfalfa leafcutting bee (Hymenoptera: Megachilidae). Annals of the Entomological Society of America 75: 407-410.

OneGen - the Canadian selection

In 1982, 2000 cells of the French univoltine (one-generation) strain (Tasei and Masure, 1978) were imported into Canada and raised under quarantine. These bees originated in southern France at a latitude of 45 degrees north where there was natural selection pressure against second generation survival. Selections were made over a 18 year period near Saskatoon, Saskatchewan. The absence of feral populations of Megachile rotunda in the surrounding area facilitated the breeding program and the propagation of selected lines. The most striking biological feature of the univoltine selection is its increase in diapause intensity. (Rank and Rank, 1989)
Tasei, J.M. and Masure, M. M. 1978. Sur quelques facteurs influencant le developpement de Megachile pacifica Panz ( Hymenoptera: megachilidae). Apidologie 9: 273-290.
Rank, G. H and Rank, F. P. 1989. Diapause intensity in a French univoltine and a Saskatchewan commercial strain of Megachile rotundata (FAB.) The Canadian Entomologist 121: 141-148.