title: The relationship between agricultural intensification and biological control: experimental tests across Europe.
abstract: Agricultural intensification can affect biodiversity and related ecosystem services such as biological control, but large-scale experimental evidence is missing. We examined aphid pest populations in cereal fields under experimentally reduced densities of (1) ground-dwelling predators (-G), (2) vegetation-dwelling predators and parasitoids (-V), (3) a combination of (1) and (2) (-G-V), compared with open-fields (control), in contrasting landscapes with low vs. high levels of agricultural intensification (AI), and in five European regions. Aphid populations were 28%, 97%, and 199% higher in -G, -V, and -G-V treatments, respectively, compared to the open fields, indicating synergistic effects of both natural-enemy groups. Enhanced parasitoid: host and predator: prey ratios were related to reduced aphid population density and population growth. The relative importance of parasitoids and vegetation-dwelling predators greatly differed among European regions, and agricultural intensification affected biological control and aphid density only in some regions. This shows a changing role of species group identity in diverse enemy communities and a need to consider region-specific landscape management.
authors.affiliation: Department of Crop Science, Agroecology, Georg-August-University, Waldweg 26, 37073 Göttingen, Germany. carsten.thies@agr.uni-goettingen.de
authors.forename: Carsten
authors.initials: C
authors.lastname: Thies
authors.forename: Sebastian
authors.initials: S
authors.lastname: Haenke
authors.forename: Christoph
authors.initials: C
authors.lastname: Scherber
authors.forename: Janne
authors.initials: J
authors.lastname: Bengtsson
authors.forename: Riccardo
authors.initials: R
authors.lastname: Bommarco
authors.forename: Lars W
authors.initials: LW
authors.lastname: Clement
authors.forename: Piotr
authors.initials: P
authors.lastname: Ceryngier
authors.forename: Christopher
authors.initials: C
authors.lastname: Dennis
authors.forename: Mark
authors.initials: M
authors.lastname: Emmerson
authors.forename: Vesna
authors.initials: V
authors.lastname: Gagic
authors.forename: Violetta
authors.initials: V
authors.lastname: Hawro
authors.forename: Jaan
authors.initials: J
authors.lastname: Liira
authors.forename: Wolfgang W
authors.initials: WW
authors.lastname: Weisser
authors.forename: Camilla
authors.initials: C
authors.lastname: Winqvist
authors.forename: Teja
authors.initials: T
authors.lastname: Tscharntke
mesh_terms: D000383:Agriculture / Q000379:methods*; D000818:Animals; D005060:Europe; D005247:Feeding Behavior; D007313:Insecta / Q000502:physiology*; D010572:Pest Control, Biological