Combining repellent and attractive aromatic plants to enhance biological control of three tortricid species (Lepidoptera: Tortricidae) in an apple orchard

Abstract

Non-host plants that are intercropped with crops can either repel or attract pests, and in some cases achieve pest management. Three aromatic plant species, ageratum (Ageratum houstonianum L.; Asterales: Asteraceae), French marigold (Tagetes patula L.; Asterales: Asteraceae) and summer savory (Satureja hortensis L.; Lamiales: Lamiaceae), were intercropped in ratios of 1:1 or 1:1:1 in an organic apple orchard to investigate the community characteristics and dynamic changes in densities of the Tortricidae species Adoxophyes orana Fisher, Spilonota lechriaspis Meyrick and Acleris fimbriana Thunberg and their natural enemies in 3 vertical strata of the orchard. Intercropping aromatic plants in the orchard increased the densities of natural enemies belonging to the Trichogrammatidae, Ichneumonidae and Braconidae and reduced the rates of increase and the densities of the tortricid species relative to the control. A correlation analysis of the densities of pest species and the densities of parasitoids indicated that the reduction in some tortricid species was related to the densities of certain natural enemy species. We concluded that intercropping with aromatic plants in apple orchards can increase the biological control of tortricid pests.