insects Review Managing Floral Resources in Apple Orchards for Pest Control: Ideas, Experiences and Future Directions Annette Herz 1,*, Fabian Cahenzli 2, Servane Penvern 3, Lukas Pfiffner 2, Marco Tasin 4 and Lene Sigsgaard 5 1 Julius Kühn-Institut, Institute for Biological Control, Heinrichstr. 243, 64287 Darmstadt, Germany 2 Department of Crop Sciences, Research Institute of Organic Agriculture (FiBL), Ackerstrasse 113, 5070 Frick, Switzerland 3 INRA, Centre de Recherche PACA, UR Ecodeveloppement, 84914 Avignon, France 4 Department of Plant Protection Biology—Unit of Integrated Plant Protection, Swedish University of Agricultural Science, P.O. Box 102, SE-230 53 Alnarp, Sweden 5 Department of Plant and Environmental Sciences, University of Copenhagen (UCPH), Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark * Correspondence:
[email protected] Received: 31 May 2019; Accepted: 6 August 2019; Published: 11 August 2019 Abstract: Functional biodiversity is of fundamental importance for pest control. Many natural enemies rely on floral resources to complete their life cycle. Farmers need to ensure the availability of suitable and sufficient floral biodiversity. This review summarizes 66 studies on the management of floral biodiversity in apple orchards, published since 1986. Approaches followed different degrees of intervention: short-term practices (mowing regime and weed maintenance, cover crops), establishment of durable ecological infrastructures (perennial flower strips, hedgerows) and re-design of the crop system (intercropping, agroforestry). Although short-term practices did not always target the nutrition of natural enemies by flowering plants, living conditions for them (alternative prey, provision of habitat) were often improved. Perennial flower strips reliably enhanced natural enemies and techniques for their introduction continuously developed.