I recently wrote a paper about this, it's really unknown how much of an effect this will have on crops. There are many native pollinators in the US, but they require a more varied source of nectar. That's not something you will see in the fields of Nebraska. Those silly Canadians have already shown that leaving 1/3 of available land untouched will actually increase the overall crop yield.
Just a couple of points, there have been die-offs in the past. The earliest was recorded in the 1800's. However, none have approached the current level of die-offs, some beekeepers are reporting 90% losses, but the average seems to be around 50%. The have been two recent die-offs at this scale, one in France and one here. The one in France was linked to a pesticide that screwed up insect navigation systems. The one in the US is the varroa mite, something that is still responsible for 10% yearly die-offs for the last ten years.
The cell-phone theory has been widely disproven. The original researchers actually disproved the theory, but the media rarely reads past the title of a research project to get to the conclusion. Poor researchers are now getting heat for something they did right the first time.
All signs do seem to point to some type of pathogen, the honey in hives will remain untouched by marauders and no new hives will form until it is irradiated.
...and stepping on them barefooted has not been proven to be successful either...
