Cursorial spiders retard initial aphid population growth at low densities in winter wheat

• Published in: Bulletin of entomological research Vol. 98; no. 3; pp. 249 - 255
• Main Authors: Birkhofer, K., Gavish-Regev, E., Endlweber, K., Lubin, Y.D., von Berg, K., Wise, D.H., Scheu, S.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.06.2008
• Subjects: Agricultural ecosystems; Agricultural land; Agricultural management; Animals; Aphididae; aphids; Aphids - physiology; Araneae; Behavior, Animal; Biologi; Biological and medical sciences; Biological control; biological control agents; Biological Sciences; Community composition; Confidence intervals; Control; detection; DNA; DNA - chemistry; DNA-based gut content analysis; ecological function; Ecology; Ekologi; Farming systems; Female; Foliage; Food Chain; functional group diversity; Fundamental and applied biological sciences. Psychology; generalist predators; Lycosidae; Male; natural enemies; Natural Sciences; Naturvetenskap; Organic farming; Pardosa; Pardosa palustris; Pesticides; Pests; Phytopathology. Animal pests. Plant and forest protection; population density; Population Growth; predation; predator functional groups; predator-prey relationships; Predators; predatory arthropods; prey detection; Protozoa. Invertebrates; Sitobion avenae; Species Specificity; Spiders; Spiders - physiology; Thomisidae; Triticum - parasitology; Triticum aestivum; Winter wheat; Xysticus; Xysticus cristatus; Germany; functional group diversity; DNA-based gut content analysis; natural enemies; generalist predators; biological control; Araneae; aphids; Sitobion avenae; Predator prey relation; Monocotyledones; Insecta; Biological control; Lycosidae; Cereal crop; Pest; Phytophagous; Homoptera; Gramineae; Beneficial animal; Angiospermae; Aphididae; Content analysis; Functional group; Aphidoidea; Gut; Araneida; Prey; Predator efficiency; Arachnida; Diet; Arthropoda; DNA; Spermatophyta; Predator; Invertebrata; Population density; Comparative study; Triticum aestivum
• ISSN: 0007-4853; 1475-2670; 1475-2670
• DOI: 10.1017/S0007485308006019

Generalist predators contribute to pest suppression in agroecosystems. Spider communities, which form a substantial fraction of the generalist predator fauna in arable land, are characterized by two functional groups: web-building and cursorial (non-web-building) species. We investigated the relative impact of these two functional groups on a common pest (Sitobion avenae, Aphididae) in wheat by combining a molecular technique that revealed species-specific aphid consumption rates with a factorial field experiment that analyzed the impact, separately and together, of equal densities of these two spider functional groups on aphid population growth. Only cursorial spiders retarded aphid population growth in our cage experiment, but this effect was limited to the initial aphid-population growth period and low-to-intermediate aphid densities. The molecular analysis, which used aphid-specific primers to detect aphid DNA in predator species, detected the highest proportion of aphid-consuming individuals in two cursorial spiders: the foliage-dwelling Xysticus cristatus (Thomisidae) and the ground-active Pardosa palustris (Lycosidae). The results suggest that manipulating the community composition in favour of pest-consuming functional groups may be more important for improving biological control than fostering predator biodiversity per se. Agricultural management practices that specifically foster effective species or functional groups (e.g. mulching for cursorial spiders) should receive more attention in low-pesticide farming systems.