Good article on Blueberry pollination. because the nectar from BB is less attractive to bees than other floral sources that are in bloom at the same time the hive populations and the number of colonies per acre is crucial to getting a good fruit set.
Pollination of apples, cherry's,peaches, raspberry, the bloom attracts the bee. In pollination orchards timing is important as to not over pollinate the fruit trees causing more fruit set than the trees can support.