Variations in prey consumption of centipede predators in forest soils as indicated by molecular gut content analysis

Predation is an important ecological factor driving animal population structures, community assemblages and consequently ecosystem stability and biodiversity. Many environmental factors influence direction and intensity of predation, suggesting that trophic linkages between animals vary between different habitats. This in consequence has particular relevance in anthropogenically altered habitats such as managed forests, where disturbance regime, tree composition and stand age may change the natural food web structure. We investigated how prey consumption of three common centipede predators (Lithobius spp., Chilopoda), representing two body sizes varies between four differently managed forest types in two regions across Germany. We hypothesized that prey preference of these generalist predators is independent of forest type but rather driven by habitat structure, prey abundance and predator body size. Applying specific PCR assays to test for DNA of three abundant prey groups, i.e. Collembola, Diptera and Lumbricidae, in the predators' guts, we tracked trophic interactions. The results showed that management type indeed has no influence on centipede prey consumption but depth of litter layer and soil pH. Trophic interactions varied between the two sampled forests regions mainly due to changes in the detection of Lumbricidae and Diptera. Also, effect of litter layer and prey abundance significantly differed between the smaller L. crassipes and the larger L. mutabilis, indicating a body size effect. The results complement food web analyses using fatty acids and stable isotopes by elucidating trophic interactions in soil in unprecedented detail.