Different habitats in arable land and Fagopyrum esculentum: their influence on aphid antagonists

Abstract: Wildflower strips, improved field margins, rotational fallows and conservationheadlands are part of the Swiss agri-environment scheme. These ecological infrastructures weredeveloped to enhance the diversity of fauna and flora in arable landscapes. However, it would befavourable if attracted beneficial arthropods significantly reduced pest infestations in nearbycrops. The aim of our project is to adapt existing ecological infrastructures to create more tailoredones for the promotion of aphid antagonists.In two field experiments we tested the importance of Fagopyrum esculentum, which is part ofseveral seed mixes for ecological infrastructures on arable land, for aphid antagonists (syrphids,coccinellids, chrysopids). In the first experiment F. esculentum was placed in pots into differenthabitats (grassy margin, hedgerow margin, winter wheat) and compared to the existingvegetation. In the second experiment aphid antagonists were counted in a strip sown with F.esculentum, an improved field margin, a grassy margin and a hedgerow margin. The firstexperiment showed that independent of the habitat F. esculentum attracted more aphidantagonists than the existing vegetation. As F. esculentum is early-flowering it is a promisingplant to support the build-up of antagonist populations. Many syrphids, coccinellids andchrysopid eggs were even found when F. esculentum was placed within winter wheat fields. Inthe second experiment most syrphids were counted on F. esculentum and in the improved fieldmargin whereas the highest number of coccinellids occurred in the improved field margin. F.esculentum offered the best egg-laying sites for chrysopids. Thus open, flower-rich habitats seemto be most attractive for aphid antagonists.