Could Bioenergy Perennial Grasses Help Pollinators?

Pamela Porter
Newsletter Issue: 
October 2015

Insects are essential to our food security. Seventy-five percent of our flowering plants, including foods like fruits and nuts, and livestock plants like clover and alfalfa, depend on pollination from honeybees, butterflies and other pollinators. The most significant pollinators, honeybees, add $19 billion of value to agricultural crops each year. However, according to the National Academy of Sciences, over the last 40 years the population of honeybees has been in steep decline. Managed bees used for honey production have decreased by 52% and populations of overwintering monarch butterflies have dropped by 82%.

In May the White House launched an “all hands on deck” national strategy to promote the health of pollinators. The strategy, National Strategy to Promote the Health of Honey Bees and other Pollinators was the result of a year-long effort led by the Pollinator Health Task Force. The Task Force was co-chaired by USDA and EPA Secretaries Tom Vilsack and Gina McCarthy. The action plan calls for research into why insect populations are declining, strengthening educational efforts and improving the quality and quantity of pollinator habitat.

The comprehensive set of steps includes: creating a pollinator habitat practice (the cost shared practice is CP-42 in the conservation reserve program (CRP) program) expanding federal funding for honeybee habitat including along highway rights of way, creating pollinator school gardens and expanding a 1500 mile pollinator habitat along the monarch butterfly’s central flyway, from Minnesota to the Texas border. Each year monarch butterflies in eastern north America migrate along this corridor, flying nearly 2500 miles, overwintering in a relatively small area of forested mountains northwest of Mexico City, known a the Monarch Butterfly Biosphere Reserve, a nationally protected site.

CenUSA Bioenergy, a USDA funded project is working to expand perennial grasses that provide habitat for pollinators. “CenUSA Bioenergy is a USDA sponsored research project focusing on the creation of a sustainable biofuels and bioproducts industry for the Midwest U.S., said Ken Moore, Project Director. “Our project’s goal of targeting perennial grasses on marginal lands can offer unique ecosystem services, including supporting beneficial insects like pollinators.”

Map of U.S showing monarch butterfly migration patterns
Above: Monarch Butterfly Fall Migration Patterns
Source: U.S. Forest Service. Base Map Source USGS National Atlas.

Recently, scientists at Michigan State University and the University of Wisconsin compared bee performance under landscapes of row crops versus perennial grass bioenergy crops. They found that bees thrived more under perennial landscapes with greater grassland and forest in the landscape versus under annual agriculture. Results from their paper, Modeling Pollinator Community Response to Contrasting Bioenergy Scenarios suggest that converting annual crops on marginal soils perennial grasslands could increase bee abundance by as much as 600% percent and bee diversity by as much as 53%. Conversely expanding annually planted bioenergy crops could reduce bee abundance by as much as 71% and bee diversity by as much as 28%.

Five states in the Midwest (Michigan, Minnesota, North Dakota, South Dakota and Wisconsin) house 65% of the nation’s honey beehives. The federal pollinator plan calls on the USDA’s Farm Service Agency and National Resource Conservation Service as well as the US Geological Service to study the impacts of honeybees in these states, tracking the plants the honeybees use for pollen and nectar during the season. The agencies will also compare the impact of different types of habitat (row crop versus CRP and pasture acreage) on honeybee populations.

“Perennial grass based bioenergy systems can be one of the tools used for improving pollinator habitat, “ said Moore. “Studies have consistently shown that increasing the biodiversity of our Midwestern landscape with native grasses like switchgrass, big bluestem and indiangrass can help support a more diverse and abundant population of predators.”

For more information on the Pollinator Action Plan see: