Population density and biomass of epigeal predatory arthropods, natural enemies of insect pests, in winter wheat fields of areas with extremely different intensity of agricultural production
1991
Basedow, T. (Giessen Univ. (Germany). Inst. fuer Phytopathologie und Angewandte Zoologie)
Density and biomass of epigeal predators were studied in fields of winter wheat in different rotations and with extremely different intensity of insecticide use, in Hesse and Schleswig-Holstein. Numbers of Trechus quadristriatus (Schrk.) (Col., Carabidae) increased with increasing use of insecticides, and with prolonged periods of undisturbed soil. On the other hand, total numbers of all predators per square metre were lowest (13,2) at the highest intensity and highest (26,9) in organic farming with red clover as pre-crop. At high intensity of agriculture, biomass (mg/square metre) was lowest in Hesse and in Schleswig-Holstein (with 19,5 resp. 18,6 mg). Again, organic farming with red clover as pre-crop yielded the highest biomass (54,6 mg/square metre). Insecticides, crop rotation and size of fields/field margins proved to be the main factors influencing numbers of epigeal predators
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