Title: Permanent weed strips a sustainable way to enhance biodiversity in orchards
Abstract: Weed strips with flowering plants in orchards can enhance the number of predatory arthro-pods, especially those predators with adults requiring nectar and pollen. The weeds used in such trials usually are very attractive nectar plants with high flowering density. In this study, weed strips mostly containing autochthonous perennial plants that should succeed in establishing in the alleys of the orchards were tested in on-farm trials in two regions of Southern Germany. The plant mix used is sown only once in the life of an orchard, and can be mulched two to three times a year. Achillea millefolium, Galium album, Carum carvi, Crepis capillaris and Picris hieriacoidescould be established in several orchards. Even if the density of flowering plants attractive for syrphids in the perennial weed strips was not very high, a significant effect on the occurrence of syrphid eggs and larvae was observed on bait trees with aphid colonies exposed in June/July 2012 and 2013. For other aphid predators, the effect was more variable. These first results indicate that permanent weed strips can be a sustainable way to enhance functional biodiversity in orchards even if the density of flowers is not as high as in strips renewed periodically. Further studies are needed to optimize plant species composition and the mulching regime. If biodiversity management is extended to all arthropod species, then plant species composition should focus not only on nectar plants for aphid predators but also on plants that are essential for other species such as wild bees, bumblebees and butterflies. [J. Kienzle, M. Foell, E. Karrer, A. Krismann & C.P.W. Zebitz (2014). Establishment of permanent weed strips with autochthonous nectar plants and their effect on the occurrence of aphid predators. Reviewed paper: 16th International Conference on Organic Fruit Growing Universität Hohenheim (Germany), February 17 to 19, 2014] ${imageDescription} Comment
