Spatial association of entomopathogenic and free-living nematode populations were analyzed at the landscape scale. Free-living nematodes were classified into functional guilds based on their trophic level (i.e. bacterivores, carnivores, fungivores, and omnivores) and life history characteristics (i.e. r-selected colonizing versus K-selected persisting species) in the soil ecosystem. Differences in life history traits were hypothesized to result in different spatial associations of populations. Spatial aggregation indices were calculated for each nematode group. Spatial associations were analyzed and compared for entomopathogenic nematodes (EPN) and each trophic/life history group of free-living nematodes based on spatial analysis of distance indices (SADIE). Spatial aggregation indices (Ia) revealed that taxa with more K-selected persisting life history were less aggregated in their habitat, whereas more r-selected colonizer life history types showed more aggregation. Spatial aggregation index of EPN populations was similar to that of relatively r-selected colonizer type free-living nematodes, which share several life history traits including high reproductive rates and insect phoresy. There were substantial spatial associations between EPN and r-selected colonizer life history free-living nematode taxa.

• Jung-Joon Park(Department of Applied Biology, Gyeongsang National University, Institute of Agricultural and Life Science, Gyeongsang National University)
• Kijong Cho(Division of Environmental Science and Ecological Engineering, Korea University)
• Casey W. Hoy(Department of Entomology, OARDC, The Ohio State University)
• Parwinder S. Grewal(Department of Entomology, OARDC, The Ohio State University)