Christiane Haschek

christiane_haschek@gmx.at

PDF der Diplomarbeit im Hochschulschriften-Service der Universität Wien


Influence of field and landscape characteristics on condition, reproductive potential and activity density of two carabid beetles in winter oilseed rape

  • The common carabid beetles, Amara similata and Poecilus cupreus, were investigated in oilseed rape (OSR) fields according to the influence of field and landscape characteristics on their condition, reproductive potential and activity density.

  • The soil index, stand density, soil cultivation index, plant cover and pest length (as a proxy for prey density) were considered as field parameters. Landscape parameters comprised the percentage of crop area, woody area, fallows, OSR fields, settlements, the length of roadside strips and of hedgerows and the Shannon-Wiener diversity index, all measured at eight different radii around each study field. Moreover, the distances to the next fallow, dry near-natural grassland, forest and OSR field were included.

  • Pest length influenced the condition factor (CF) and activity density of both species and sexes significantly (positive response for CF, negative for activity density). Furthermore, the CF of female A. similata was significantly positively influenced by stand density, the CF of male A. similata by soil index. In P. cupreus activity density of both sexes was significantly related to soil index. Oocyte numbers of A. similata were significantly negatively related to the distance to the next fallow. When analysing exclusively the influence of the OSR pests Meligethes aeneus, Ceutorhynchus napi and Dasineura brassicae, the abundances of M. aeneus and C. napi were most important in explaining the CF and activity density of both carabid species and sexes, except the CF of female A. similata.

  • In eight of ten cases analysing simultaneously the influence of field and landscape parameters by General Linear Models, pest length proved to be the most important parameter explaining the CF, reproductive potential and activity density of A. similata and P. cupreus. Landscape characteristics at various spatial scales were far less important.

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