Characterization of long-legged fly (Diptera: Dolichopodidae) communities in Ohio agroecosystems

Biological control is a vital ecosystem service provided by a diverse guild of predators in agroecosystems.  Biodiversity is thought to be linked to ecosystem functioning through more efficient resource capture and niche partitioning.  Understanding the factors that impact the diversity of these predators is therefore important to our understanding of how to enhance biocontrol services.  Long-legged flies (Diptera: Dolichopodidae) are a particularly ubiquitous yet understudied group of insect predators that are common in all habitats in Ohio, including agricultural systems.  Previous studies have shown that these flies are sensitive to environmental changes, at least in natural systems like grasslands and reed marshes.  The goal of this study is to determine how field-level factors such as pesticide use and landscape-scale factors such as composition and heterogeneity influence the community assemblage of Dolichopodidae found in agroecosystems.  During the summer of 2013 and 2014, pan trapping was used to sample the long-legged fly community present in produce farms across northeast Ohio that represented a gradient of landscape complexity and management intensity (tillage, pesticide use, etc.).   Sweet corn, summer squash, and unmanaged grasslands were sampled.  Over 8,000 flies representing ten dolichopodid genera were found in 2013.  Analysis of the 2013 data shows that overall dolichopodid abundance was actually higher in crop habitats than unmanaged habitats, but that habitat preference varied by genus.  Identifying which factors are driving the diversity of this family of flies will help us understand how to maximize the biological control services being provided.