title: Predator community structure and trophic linkage strength to a focal prey.
abstract: Predator abundance and community structure can affect the suppression of lower trophic levels, although studies of these interactions under field conditions are relatively few. We investigated how the frequency of consumption (measured using PCR-based gut content analysis) is affected by predator abundance, community diversity and evenness under realistic conditions. Soil arthropod communities in sixteen maize fields were measured (number of predators, diversity [Shannon H] and evenness [J]), and predator guts were searched for DNA of the focal subterranean herbivore, the corn rootworm (Diabrotica virgifera). Predator abundance and diversity were positively correlated with trophic linkage strength (the proportion positive for rootworm DNA), although the latter characteristic was not significantly so. The diversity and evenness of the predator community with chewing mouthparts were strongly correlated with their linkage strength to rootworms, whereas the linkage strength of fluid-feeding predators was unaffected by their community characteristics. Within this community, chewing predators are more affected by the rootworm's hemolymph defence. This research clearly shows that predator abundance and diversity influence the strength of a community's trophic linkage to a focal pest and that these community characteristics may be particularly important for less palatable or protected prey species. We also make the case for conserving diverse and abundant predator communities within agroecosystems as a form of pest management.
authors.affiliation: USDA-ARS, North Central Agricultural Research Laboratory, 2923 Medary Avenue, Brookings, SD, 57006, USA.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Lundgren
authors.forename: Janet K
authors.initials: JK
authors.lastname: Fergen
mesh_terms: D000818:Animals; D001181:Arthropods / Q000033:anatomy & histology / Q000502:physiology*; D001517:Coleoptera; D020387:Food Chain; D005766:Gastrointestinal Contents; D011157:Population Dynamics; D011235:Predatory Behavior; D017422:Sequence Analysis, DNA; D012987:Soil; D003313:Zea mays
chemical_list: D012987:Soil
keywords: Diabrotica virgifera; biological control; predator abundance; predator diversity; prey defence; soil food web