Flowering plant patches to support the conservation of natural enemies of pests in apple orchards

Conventional farming imperils diversity and abundance of natural enemies of crop pest in agroecosystems. Thus, conservation biological control (CBC) receives increasing attention in sustainable agricultural practices in agroecosystems as a tool to support the presence of natural enemies. The purpose of the present study was to investigate whether sown flowering mixture (FM) patches in the groundcover of three apple orchards can support more natural enemies of pests compared to wild plant (WP) patches already present on the groundcover of the orchards. Flowering measurements and suction samplings of arthropods were conducted on the patches and apple tree canopy. The results showed that the FM harbored more predators on the apple orchards’ groundcover compared to WP. Especially, heteropteran predators of the family Anthocoridae were present only on the FM. The FM provided floral resources consistently to the support of natural enemies throughout a long period when the WP was not in bloom. No effect of the FM was recorded on the natural enemies’ abundance on the apple tree canopy but neither an increase of pests. Vicia faba supported parasitoid wasps early in the season, Eruca sativa harbored mainly predators and Coriandrum sativum supported both parasitoid wasps and predatory arthropods later in the season whereas Calepina irregularis promoted the presence of parasitoid wasps, highlighting the potential role of certain weed species in conservation biological control. Exploitation of the sown species as supplementary to weed flora is suggested for an optimal conservation practice of natural enemies in apple orchards. • Sown patches enhanced predators but not parasitoids in apple orchard groundcover. • Sown flowering patches supported natural enemies when wild flowers were not in bloom. • Natural enemies’ abundance on apple tree canopy was not affected. • No increase of apple pests was recorded near the flowering patches in the orchards. • Sown patches and certain weeds can be complementary in preserving natural enemies.