The U.N. has released a brief report (pdf) on the global state of pollinators. As with most such reports, it only contains substantive information about one species, the western honey bee, as data do not exist for the vast majority of other pollinators.
The report contained this figure, which I have modified to indicate the arrival of Colony Collapse Disorder:
For all the hoopla over CCD, the reality is that non-African Apis mellifera on the North American continent has been declining for decades, and that CCD, whatever it may be, is just the latest in a string of challenges. Data are sketchy for other pollinators, but there are reasons to believe the decline is more general.
If I may be permitted to speculate, I suspect the gradual decline reflects gradual changes in landscape use and commerce since the 1950s. The rise of large-scale agriculture and urban sprawl, together with a decrease in the small farms inclined to beekeeping, has decimated the diversified landscape that supported earlier populations. Concurrently, globalization brought new bee pests to our shores- look at the effect of Asian Varroa mites in the 1980s!- and has increased the traffic of pests around the continent.
If we wish to return the domestic honey bee to its historically large population sizes, we’d do well to focus on larger landscape management issues rather than zeroing in on particular diseases or afflictions. Otherwise, we risk not seeing the forest for the bees.