All told, scientists studied 30,000 specimens. They found that in the Northeastern United States, the diversity of bumblebee species declined by 30 percent, and the diversity of bee species overall, by 15 percent between 1872 and 2011.
A new study by numerous scientists was published in Proceedings of the National Academy of Sciences this week. One of them, Jeroen Scheper, a graduate student at Alterra, a research institution at Wageningen University in the Netherlands, said, “There were a lot more flowers in the landscape before.” In other words, the fate of the diminished or extinct species was tied to the fate of the plants they pollinated, many of which had been replaced by crops.
Mr. Schleper and his colleagues believe that without the preferred kind of pollen, the bee larvae suffered; and that bigger bees were at greater risk than smaller bees. The story cautions that in addition to the loss of food sources, bee declines may also be due to the loss of nesting sites.