Managing Alternative Pollinators

The Advance and Decline of the US Leafcutter Industry

After introduction, the alfalfa leafcutter bee spread westward to the Pacific coast, in the process becoming established as an important wild pollinator of alfalfa for seed production. By the early 1960s, the leafcutter’s value as a pollinator was well recognized, and alfalfa growers in western states had developed various artificial nest systems for rearing large numbers of the bee.

The leafcutter bee was successfully managed, and huge annual population increases were common in the 1960s and 1970s. As populations increased, however, so did new parasites and diseases, particularly a fungal disease called chalkbrood (Ascosphaera aggregata). The entrenched production practices of US beekeepers failed to adapt to these challenges, and as a consequence, the leafcutter industry collapsed in the 1980s. Since then, numerous leafcutter beekeepers and equipment manufacturers have gone out of business.

Meanwhile, Canadian producers pioneered new management practices which have kept the alfalfa leafcutter bee in common use. Today Canada has emerged as a major producer of both leafcutter bees and alfalfa seed. Unfortunately many of the Canadian management methods rely heavily on a combination of potent fumigants, pesticides, and disinfectants, many of which are not approved in the US.

With the continued decline of the European honey bee in the US, there is a renewed interest in the alfalfa leafcutter bee—not just to pollinate alfalfa, but also to pollinate crops like blueberries, cranberries, and various vegetables. Unfortunately, there has been little corresponding research into improved management methods for this bee. Suppliers of bees and equipment in the US are also uncommon.

The following recommendations are an attempt to suggest more sustainable management practices with the goal of reviving the alfalfa leafcutter bee as a managed pollinator in the US.