Wild bees “are disappearing in many of the country’s most important farmlands,” including the Central Valley of California, the No. 1 state for fresh fruits and vegetables, says the University of Vermont. A study led by researcher Insu Koh found that 39 percent of U.S. cropland that depends on pollinators “faces a threatening mismatch between rising demand for pollination and a falling supply of wild bees.” The study is to appear in the Proceedings of the National Academy of Sciences.
The researchers created the first national map of wild bees and identified 139 counties in key agricultural areas of California, the Pacific Northwest, the Midwest, the northern Plains and the lower Mississippi River valley where the pollinator mismatch would be the worst. The counties specialize in orchards and produce farms that rely heavily on pollinators, or grow vast amounts of corn, soybeans and cotton which rely less on pollination by insects.
“Pesticides, climate change, and diseases threaten wild bees — but the new study also shows that their decline may be caused by the conversion of bee habitat into cropland,” says U-Vermont. “These results reinforce recent evidence that increased demand for corn in biofuel production has intensified threats to natural habitats in corn-growing regions.”
The decline in wild bees comes at the same time that honeybee numbers are falling. In May, the White House issued a strategy to bolster the population of pollinators. The goals include reducing winter losses of bee colonies to 15 percent or less, increasing the population of monarch butterflies and restoring or enhancing 7 million acres of land over the next five years for pollinators.