The U.N.'s environmental agency warned in a new report Thursday that the world's bee population is likely to keep declining unless humans change the way they manage the planet.
North America, Europe, the Middle East and parts of Asia have been affected by losses in bee numbers, the report said. It called for farmers and landowners to be offered incentives to restore bee habitats, including key flowering plants.
The U.S. Department of Agriculture said the U.S. honey-producing colonies have dropped from a population of 5.5 million in 1950 to 2.5 million in 2007.
The bees are needed to pollinate crops that feed the world's growing population. Of the 100 crop species that provide 90 percent of the world's food, more than 70 are pollinated by bees, the U.N. report said.
"Human beings have fabricated the illusion that in the 21st century they have the technological prowess to be independent of nature," said Achim Steiner, the executive director of the U.N.'s environmental program. "Bees underline the reality that we are more, not less dependent on nature's services in a world of close to 7 billion people."
The global economy and international trade appears to be contributing to bee losses. New kinds of pathogens that can be deadly to bees are migrating from one region to another as a result of trade, the report said.
Peter Neumann, a co-author of the report, said the transformation of rural areas in the past 50 years have triggered a decline in wild bees and other pollinators. The shortfall is being made up by managed colonies and "industrial scale" hives.
"We need to get smarter about how we manage these hives, but perhaps more importantly, we need to better manage the landscape beyond, in order to cost-effectively recover wild bee populations to far healthier and more sustainable levels," Neumann said.
In North America, losses of honey bee colonies since 2004 have left the continent with fewer managed pollinators than at any time in the past 50 years.
Beekeepers in China have recently losses of bee colonies, as have beekeepers in Japan, the report said.
One of the sources of bee losses, the Varroa mite, has killed off bees in Europe, North America, Japan and the Middle East, the report said. Africa, South America and Australia have not been touched by the Varroa mite issue.