Study: Biomass crops attract beneficial insects

By Anna Austin
Posted January 27, 2010, at 3:56 p.m. CST

A study recently published by Michigan State University has found that diverse biomass crop plantings such as switchgrass and native prairie grasses attract a higher number of beneficial insects than nondiverse crops such as corn.

The purpose of the study was to assess the implications of different biofuel crops for beneficial insects -pollinators and pest controllers such as bees-that provide valuable ecosystem services in agricultural landscapes. MSU entomology professor and study co-author Doug Landis said existing plantings throughout southern Michigan that were not actively being managed as biofuel crops were sampled, and it was found that the crops contained a diverse bee community comprised of 75 species. Overall, bees were three to four times more abundant in switchgrass and prairie grass than in corn.

The study suggests that there are important consequences for the insects in the type of biofuel crop that is grown. Results indicated that as an annual crop with low plant diversity and high levels of soil disturbance, corn tends to have low abundance and diversity of these beneficial insects. Contrastingly, both perennial grassland-based biofuel crops harbored a higher abundance, species richness, and diversity of beneficial arthropods compared with corn monocultures, according to the study.

The researchers believe their findings suggest important policy implications. Particularly, on U.S. government policies toward cellulosic biofuels being driven by ethanol production targets that influence research focused on attaining high biomass productivity and corresponding efficiency in processing, without explicit consideration of the landscape-level environmental impacts such systems may induce.

Landis told Biomass Magazine that a caveat he and his team has is that as these crops are "pushed" for higher yield that diversity will likely decline. Future bioenergy policy should be developed to explicitly enhance biodiversity as a means of improving the delivery of ecosystem services by agricultural landscapes, they contend, while also meeting biofuel production targets.

Funding for the study, published in January in the BioEnergy Research Journal, was provided by the U.S. DOE Great Lakes Bioenergy Research Center, the Michigan Agricultural Extension Station and the USDA National Research Initiative program.