Arthropod Diversity in Corn and Mixed Prairie Biofuel Crops

Abstract

Competition for agricultural resources has been increasing due to the food and fuel demands of increasing human populations. Increasing demand for the agricultural production of both food and biofuel crops makes maximizing ecosystem services imperative. Arthropods provide ecosystem services to crops in the form of biocontrol of pest insects and pollination. Arthropod diversity has been correlated with plant diversity, however, most bio-ethanol is produced from corn grain, grown as a monoculture. Cellulosic ethanol production uses all plant parts, thus native perennial grasslands have the potential to be used in biofuel production while allowing for greater overall biodiversity and associated arthropod mediated ecosystem services. The purpose of this study was to compare mixed prairie to corn in terms of the abundance and diversity of select groups of arthropods across a growing season. Four corn and four mixed prairie sites were selected in southwest Michigan. Each site was surveyed three times, once each in June, July, and August. Native bees require nesting sites and floral resources in order to provision nests for developing larvae. Therefore, we expected to see more bees and more kinds of bees in mixed prairie sites than in corn sites. Except for during the month of June, when bee abundance was significantly greater in mixed prairie than in corn, no significant effect of biofuel crop was detected for native bees. The trend for wasps was similar to that of bees, with more wasps in prairie than in corn. Wasps require nectar as adults and are expected to be found in association with floral resources. Syrphids appeared to favor corn over mixed prairie, although the difference was not significant. This trend may be related to corn harboring a favored resource of the syrphid larvae.