Solitary bees in North American agriculture: a perspective

Author states that on page 50 and in table 2, prior to management of alfalfa leaf-cutting bees and alkali bees for US alfalfa seed production (beginning in the 1960’s), growing was spread across entire northern tier of states. Acreage was vast (1.4 million acres) and yields were generally poor (135 lbs/acre). With pollination taken over using abundant managed M. rotundata and Nomia melanderi, production shifted to xeric regions of the Pacific Northwest (esp. Oregon, Washington and Idaho) and California. Overall production acreage shrank 6x to 250,000 acres because yields were improved to as much as 1,800 lbs per acre (my note...more realistically, the average grower in average year is getting more like 1100 pounds of clean seed per acre, but still, that is a 8x increase).