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Research article - Peer-reviewed, 2017

Pollen beetle mortality is increased by ground-dwelling generalist predators but not landscape complexity

Riggi, Laura G.; Gagic, Vesna; Rusch, Adrien; Malsher, Gerard; Ekbom, Barbara; Bommarco, Riccardo


Biological control of crop pests by naturally occurring arthropods depends on the entire community of natural enemies, but generalist predators and parasitoids are rarely considered in the same study. Also, the level of biological control in the field is affected by both within-field and landscape scale management. A multi-taxa approach that integrates multiple scales of management is needed to understand drivers for pest mortality. We examined local (weed cover and soil characteristics) and landscape (proportions of semi-natural and oilseed rape habitat) effects on natural enemy communities and biological control of pollen beetles in 15 oilseed rape (OSR) fields in Sweden. We found that agricultural intensification at the local (low weed cover) and landscape scale (low proportion of semi-natural area) increased evenness of generalist predators, but had no effect on the densities of pests and their natural enemies. This suggests that the generalist predators in OSR are well adapted to crop lands, at least within the examined gradient. Increasing OSR in the landscape decreased parasitoid densities and increased pest density, indicating a potential loss of pest control services by specialist natural enemies in landscapes with a high proportion of OSR. Finally, pollen beetle mortality increased with ground dwelling generalist predator abundance and soil clay content. Parasitism rates did not affect pest mortality, which is interesting as parasitoids have been considered major control agents in OSR. The hypothesis that increasing semi-natural habitat in the landscape enhances natural enemy abundances and species richness in agricultural landscapes was not supported. Local measures targeting generalist predators appear as a reasonable strategy to maximize pollen beetle control.


Meligetlzes aeneus; Brassica napus; Intermediate landscape complexity hypothesis; Predator community; Natural enemies; Biological control

Published in

Agriculture, Ecosystems and Environment
2017, volume: 250, pages: 133-142

Authors' information

Swedish University of Agricultural Sciences, Department of Ecology
Gagic, Vesna
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Rusch, Adrien
National Institute of Agricultural Research (INRA)
Swedish University of Agricultural Sciences, Department of Ecology
Ekbom, Barbara
Swedish University of Agricultural Sciences, Department of Ecology
Swedish University of Agricultural Sciences, Department of Ecology

Associated SLU-program

SLU Network Plant Protection

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