Canonical correspondence analysis demonstrates unique soil conditions for entomopathogenic nematode species compared with other free-living nematode species

Abstract

Entomopathogenic nematodes are ubiquitous yet relatively little is known of their naturally occurring spatial distributions and ecological functions compared with more easily observable taxa. This study provides the most detailed accounting to date of the soil habitat conditions associated with presence and abundance of naturally occurring populations of entomopathogenic nematodes compared with other free-living nematode species. We sampled at least 100 sites representing six habitats in an agroecosystem. Nematodes were extracted and soil physical and chemical conditions were measured for each site and the species–environment relationship was analyzed by canonical correspondence analysis. Both biotic and abiotic components of the soils were important in the relationship between free-living nematodes and soil conditions. Entomopathogenic nematodes were associated with a different set of soil conditions than other free-living species. The conditions favoring entomopathogenic nematodes were most similar to the most r-selected bacterial feeders and may result from an adaptive syndrome associated with their unique life history. Soil conditions associated with entomopathogenic nematode abundance included increased enrichment and food web structure, lower P, higher K, and lower C:N ratio. Soils in agroecosystems might be manipulated through soil fertility management practices to increase the ecosystem services provided by entomopathogenic nematodes.