As more land around the world is planted with crops that need bees and other pollinators to grow, the diversity of crops is falling, putting those pollinator species at risk while threatening global food security, according to new research from a multinational team that includes a University of Maryland biologist.

The study, published today in Global Change Biology, is the first global assessment of the link between crop diversity trends and agricultural dependence on pollinators.

Using U.N. Food and Agriculture Organization annual data from 1961 to 2016, the study showed that pollinator-dependent crops expanded in area by 137%, while crop diversity increased by 20.5%. This imbalance is a problem because agriculture dominated by just one or two types of crops only provides nutrition for pollinators at times of the year when crops are blooming, the researchers said. Agricultural diversity results in crops that bloom at different times, providing more stable sources food and habitat for pollinators.sweat bee

“This work should sound an alarm for policymakers who need to think about how they are going to protect and foster pollinator populations that can support the growing need for the services they provide to crops that require pollination,” said David Inouye, professor emeritus of biology at the University of Maryland and a co-author of the research paper.

Globally, a large portion of the total agricultural expansion and increase in pollinator dependence between 1961 and 2016 resulted from increases in farming of soybean, canola and palm crops for oil. Such crops are associated with environmentally damaging industrial farming practices such as large-scale single-crop agriculture (monoculture) and use of pesticides that threaten pollinators.

Particularly vulnerable to agricultural instability from pollinator loss are Brazil, Argentina, Paraguay and Bolivia, where expansion of soybean farms has driven deforestation and replaced rich biodiversity that supports healthy populations of pollinators. Malaysia and Indonesia face a similar scenario from the expansion of oil palm farming.

“Farmers are growing more crops that require pollination, such as fruits, nuts and oil seeds, because there’s an increasing demand for them and they have a higher market value,” Inouye said. “This study points out that these current trends are not great for pollinators, and countries that diversify their agricultural crops are going to benefit more than those that expand with only a limited subset of crops.”

Beyond South America and Asia, the study points out that increasing need for pollination services without parallel increases in diversity puts agricultural stability at risk in European countries like Australia, the United Kingdom, Germany, France, Austria, Denmark and Finland.

In the U.S., meanwhile, industrial-scale soybean farming has outpaced agricultural diversity.
 
“This work shows that you really need to look at this issue country by country and region by region to see what’s happening because there are different underlying risks,” Inouye said.

Inouye said the researchers hope the study will spur policymakers and resource managers to introduce more pollinator-friendly management practices, such as reducing insecticide use, planting edge rows and flower strips to provide nest sites and food for pollinators, and restoring seminatural and natural areas adjacent to crops.