Hi, as a highbush blueberry farmer I can tell you that what you are seeing is fairly common in unsprayed blueberries. Botyritis and anthracnose are two fungal diseases that can cause these symptoms. Pollinated fruit corollas can also turn brown but you will still get fruit. A good description of these can be found at the link to Cornells website included below.
As far as honeybees go they dislike blueberry blossoms because their tongues are too short to reach the nectaries easily. In my 3 acre plantation we try to force the issue by bringing in at least 12 strong hives or around 750000 bees. Also we never spray an insecticide when the bees are present. That would be pretty foolish after paying 900 dollars for them.
If I ever get over to my place at 60 cow I will look at them.
http://www.fruit.cornell.edu/berryto...ownflowers.htm