>all that we need do is to switch to say Apis Cerana and pollination still takes place.

Actually, there is a groundswell of interest in native pollinators. The old notion that only honey bees can do pollination economically is being disproved: 

> Concern over the general decline in honey bee populations in the United States, including the recent devastation caused by colony collapse disorder, has prompted increased interest in understanding native bee populations. Winfree et al. (2007) indicate that native pollinators can provide "insurance" against honey bee losses. In fact, Greenleaf and Kremen (2006) demonstrated that honey bee pollination efficiency on sunflowers increased nearly five-fold when native bees were present. Native pollinators are known to contribute important pollination services in many crops (Klein et al., 2007)

A Checklist of the Bees (Hymenoptera: Apoidea) of Pennsylvania
LEO R. DONOVALL, III AND DENNIS VANENGELSDORP
JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY 83(1), 2010, pp. 7–24

PLB

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