The collective body of research “resulting from an unprecedented effort by the scientific community … indicates that bee declines cannot unambiguously be linked to a single causative factor,” said May Berenbaum, professor at the University of Illinois Urbana-Champaign.“This is despite the fact that media outlets have, on multiple occasions, declared that the mystery has been solved.”

A fourth-generation beekeeper, Zac Browning, said the report “makes it fairly clear that bee decline is complicated but not a mystery. It’s really about colony stress. The report does a good job of breaking the known, major stresses into four categories: pest and pathogens, pesticide exposure, nutrition and genetics…

“Since the 1950s, the average farm size in America has grown from about 200 acres to about 400 acres. Average crop yields have increased two- and three-fold. At the same time, honeybee colonies have decreased from about 5.5 million to 2.4 million, today.”

Browning also pointed out the problems for maintaining healthy colonies when there is a lack of crop diversity. “There is roughly 370 million cultivated acres in the lower 48 states. This year, 96 million of those acres will be planted in corn. Cornfields are of no value to honeybees nutritionally.”

Further, “We’re losing suitable habitat for honeybees at unsustainable rates,” said Browning. “In just the last five years we’ve lost over 10 million acres of conservation land, mostly to commodity farming.

“At the same time, while we may be using less pesticides by weight – and perhaps less acutely toxic products – there are few commodity crop acres that aren’t treated with these products. As there is less diversity in the landscape the potential for exposure is amplified, especially as bees are also concentrated and asked to do more and more in terms of pollinating crops. As that demand continues to rise, the supply of bees is steadily declining.”

Browning said what is needed has become clearer. “We need an abundance of clean, nutritious forage for bees. We need better pesticide practices and policies. We need tools to manage pests and disease. We need genetic stocks that give us advantages and resilient strains to pests and pathogens.”