Beneficial insect communities in semi-natural grasslands and monocultures managed for conservation benefits

Pollinating insects in many ecosystems have shown declines in abundances and species richness. Biofuel crops (e.g. corn) have expanded in recent years due to ethanol demand. Some crops, such as corn, used for biofuels have been shown to be detrimental to pollinating communities. We tested four treatments of alternative biofuel crops to determine whether these crops could be used as surrogates for corn without disrupting pollinating insect communities.  Our twelve 25 acre experimental plots, located in Prairie Mississippi, included 1) native grass mixture without cattle, 2) native grass mixture with cattle, 3) Indian grass (Sorghastrum nutans) with cattle and 4) Bermuda grass (Cynodon dactylon) with cattle. Native grass mixtures were comprised of  1) Big Bluestem-Andropogon geradii, 2) Little Bluestem-Schizachyrium scoparium, 3) Indian grass. Overall, Bermuda grass plots contained the lowest abundances and genera richness of pollinating insects. Various insect groups (e.g. bees, butterflies, syrphid flies) showed higher abundances and species richness within plots containing native grasses. The presence of cattle seemed to decrease genera richness and abundances. Overall, our data supports the notion that native grasses rather than non-native grasses (e.g. Bermuda grass) may allow for continued biofuel production without disrupting pollinating communities.