Are long-legged fly (Diptera: Dolichopodidae) assemblages altered by agroecosystem management or surrounding landscape composition?

Biodiversity of predators is proposed to enhance ecosystem functioning through more efficient resource capture.  Therefore, understanding the factors that structure predator communities is vital to the provision of biological control services.  Long-legged flies (Diptera: Dolichopodidae) are a particularly ubiquitous yet vastly 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 objective of this study is to determine how local management such as tillage and pesticide use, along with landscape-scale composition and heterogeneity, influence the diversity and abundance of these flies within agroecosystems.  We predicted that long-legged fly diversity would be higher on farms within more complex landscapes and with less intensive pesticide use and tillage regimes.  During the summer of 2013, pan trapping was used to sample the long-legged fly community present in produce farms along gradients of landscape complexity and management intensity.   Landscape composition data were collected though ground verification of the area surrounding the farms and management data were gathered through surveys distributed to the growers.  Flies are currently being identified to the genus level and subsequent statistical analysis will elucidate any patterns in the data.  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.