Auswirkungen verschiedener Ackerkulturen auf die Laufkäfer (Coleoptera, Carabidae)

Summary

Carabid populations (species diversity and abundance) in different crops were investigated during the period from April to July 1993 to 1995. The study was carried out on two farms in North-Western Switzerland. Nine fields with winter cereals (4x wheat, 2x spelt, 2x barley, lx rye), three rape fields, five spring cultures (3x maize, lx soybeans, lx potatoes) and an arable meadow were studied. In winter cereals, more carabid species were found than in spring cultures. In barley, we recorded fewer carabid species and individuals, larger numbers of hygrophilaus carabids and a more even population structure than in the other cereals. In rape, we recorded the highest numbers of carabid species and individuals, and very large numbers of Amara similata and A ovat(t. Rape turned out to be an attractive foocl plant for A. similata and A. avata. Pterosticlms melanarius was less abundant in rape than in cereals. In the springcultures, we found less species and individuals than in cereals or rape. but a lügher share of xerothermophilous carabid species. There were significant differences in the carabid populations on the two farms, which might be explained by the different farming methods. One farm is managed organically, while the other farm applies integrated production. Among others, organic farms are not allowed to use herbicides. Therefore, the weed flora on organic fields is generally richer than on other fields, and the microclimate on the soil smface can be favourable. From April to June, Poecilus CUJJreus was the most frequent carabid species on both farms. In July, P. cupreus was still the most abundant carabid on the organic farm, while Pterostichus melanarius became the most abundant carabid on the integrated farm. Due to the bigher weed diversity Amara plebeja, A. fami/iaris,Diachmmus germanus and Stenolophus teutonus occurred mostly more abundant on the organic fields.