Southwick wrote in 1992:  

IN NORTH AMERICA, there are well over five million honey bee (Apis mellifera L.) colonies managed by >200,000 hobby, sideline, and commercial beekeepers, and in the United States, over one million honey bee colonies are rented yearly for pollination services in agricultural crops. Demand for pollination services is greatest in monoculture and where hybrid seed is required. It is clear that honey bees have often been credited with pollination services that are actually performed by other bee species (Duncan 1940, Parker et al. 1987). 

It has been known for decades that many other types of bees as well as other insects pollinate crops, but their economic value remains unknown, and they are little appreciated. In some regions and under certain conditions, the effect of no honey bees can be devastating. In other areas, honey bees can increase crop quality or yields somewhat, but their absence would not cause a great economic loss. 

In New Brunswick, honey bees were not needed on blueberries until pesticides devastated native unmanaged pollinators. After effective cleanup of the environment, these natural populations of pollinators recovered. During intervening years, honey bees were required and without them there would have been no harvestable crop. On the other hand, honey bees are not useful on cranberries in Ontario unless native bumble bee populations are very low. 

Southwick, E. E., & Southwick Jr, L. (1992). Estimating the economic value of honey bees (Hymenoptera: Apidae) as agricultural pollinators in the United States. Journal of Economic Entomology, 85(3), 621-633.

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