A selection of wild flowers to enhance Prays oleae natural enemies

Abstract: The diversity of vegetation in agroecosystems can provide arthropod natural enemies with food sources (pollen, nectar and alternative hosts and preys) and shelter (for mating and overwintering), potentially enhancing natural pest control and reducing dependence on chemical pesticides. Accordingly, the establishment of agroecosystems with flowering plants able to provide the resources needed by natural enemies to maintain and enhance their reproduction, survival and efficacy and without favour pests is an important challenge. The olive moth, Prays oleae (Bernard) is an important pest of olive groves, developing three generations per year each one damaging one organ of the tree (flowers, fruits, leaves). This pest is naturally controlled by several insects able to reduce its populations, including the predator Chrysoperla carnea s. l. (Stephens) and the parasitoids Ageniaspis fuscicollis (Dalman), Chelonus elaeaphilus Silvestri and Elasmus flabellatus (Fonscolombe). In the last years, the effect of flowering plants, frequently found in Portuguese olive groves, on the survival and reproduction of those natural enemies were analysed in several laboratory studies. Based on the compilation of the results of those studies, we present a set of plants to be installed in field studies in order to ascertain their effect in enhancing natural enemies and their efficacy as natural control agents of P. oleae. According to the plant adequacy to common management practices carried out in olive orchards, the selected set of plants can be classified in species suitable for olive interrows [e. g. Andryala integrifolia L., Borago officinalis L., Echium plantagineum L., Lamium purpureum L., Malva sylvestris L., Silene gallica L., Tolpis barbata (L.), Veronica persica Poir] and species suitable for olive edges or small flowering patches [e. g. Conopodium majus (Gouan) Loret, Foeniculum vulgare Mill., Lonicera hispanica Boiss et Reut., Daucus carota L., Lavandula stoechas L.].