Ant communities of cornfields in polyculture versus monoculture farms of the Roanoke Valley of Virginia

We characterized ant communities of cornfields from monoculture and polyculture farms in the Roanoke Valley of Virginia.  We used pitfall traps to collect ants in cornfields, and in other crops and areas of the farms.  In total, we collected 2,214 ants from 20 species at two sites.  The monoculture corn farm had a lower ant abundance (17 ants/trap) than the polyculture farm (76 ants/trap).  Observed species richness was similar at both sites (16 species monoculture; 17 species polyculture)  but estimated species richness was much lower for the monoculture corn (Chao 1= 17.5 species) compared to the polyculture corn (Chao 1= 29.5 species).  The sites had 13 of their ant species in common.  Only Prenolepis imparis, the small honey ant, was among the five most abundant species at both sites; the other four most abundant ants at each site were different species.  The invasive Pachycondyla chinensis, the Asian Needle Ant, was among the top five most abundant on the monoculture corn farm.  Despite the substantially smaller land area and more urban setting of the polyculture farm, the polyculture corn featured increased ant species richness and abundance which may benefit ecosystem function, given the ecological roles played by ants on farms.  The monoculture farm employed genetically modified, B.t.-corn, however, while the polyculture farm did not use a genetically modified corn variety, creating another potential explanation for differences in the ant communities of the two cornfields.