This may interest some here.
Here is a link that might be useful: more bee trouble
Last spring we had incomplete pollination of our blueberry shrubs, which resulted in a harvest that was smaller than expected. We harvested one gallon of fruit, but we expected to harvest 3 gallons, based on previous years. I had noticed that our bumblebees were scarce while the shrubs were flowering, but I thought this was because of the wet and dreary(overcast) weather that dominated in April. Now I am not so sure. The local population of bumblebees did seem to recover later in the year, and by fall, I was seeing lots of them out in our yard. We also have honeybees here, so the two populations do come in contact. In the fall, our New England asters are blooming, and that is where all of the bees congregate. I don't keep honeybees, but there are two hives that I know of within 1/2 mile of this location.
I saw a bee yesterday - that's the earliest I've ever seen one. We've been having spring temperatures, and I guess they woke up. There is nothing blooming yet.