Einfluss einer Low-Input-Strategie auf tritriphische Systeme in Winterweizen und Erbse

Long tenn effects of low-input compared with high-input pesticide use were investigated in a convcntional farm in thc Magdcburgcr Bocrde using half-fields-comparisons from 2004-2006. Thrcc fields were divided into two halves. One half was characterised by 50% reduced pesticide <loses and the other half by good plant protection practise ( 100% ). The effects of both strategies on tritrophic systems crop - aph ids - predators were studied regarding arthropod densities and biodiversity as weil as potential ofnatural regulation of aphids. Here, the results of one field were presented. In all three years statistically significantly more aphids and predators were found in the low-input variant than in the high-input variant after insecticide use. The abundance and biodiversity of carabids were not affected by the reduced pesticide dose. The first indication of a long tenn effect was detected in the fonn ofhigher weed occurrence in the low-input strategy before herbicide use. lt is concluded, that aphids profit to a greater extent from the reduced level of pesticide use than do their predators. Thus, the enhanced potential ofnatural regulation failed to reduce aphid densities.