Ecological infrastructures in sustainable olive growing: studies about Prays oleae (Bernard) and its natural enemies

Doutoramento em Engenharia Agronómica - Instituto Superior de Agronomia - UL

The olive tree (Olea europaea L.) has been shaping and characterizing landscape and culture in the Mediterranean basin. This tree is attacked by pest that can cause significant losses. This thesis was focused on the conservation biological control of one of its most damaging pests: the olive moth, Prays oleae (Bernard). Naturally, a large number of parasitoid and predator species are associated to this pest, and in order to satisfy their needs they make use of ecological infrastructures occurring in the olive grove agroecosystem. However, how these ecological infrastructures can be used to enhance the olive moth conservation biological control needs to be disentangled. For that, two approaches were followed. First, the influence of ecological infrastructures on P. oleae and its natural enemies was analyzed through field surveys. Then, different food resources were evaluated as potential foods for P. oleae and its natural enemies, i.e., the parasitoid Elasmus flabellatus (Fonscolombe) and the predator Chrysoperla carnea s. l. (Stephens). In the first approach, P. oleae was found to disperse throughout non-crop patches, although the implications for the pest population are unknown. The heterogeneous landscapes composed by herbaceous and woody vegetation around the olive groves were exploited by syrphids as food sources. Finally, ground covers within the olive groves favored the parasitoid Ageniaspis fuscicollis (Dalman) while the herbicide application diminished it. In the second approach, insects’ honeydews [Saissetia oleae (Olivier) and Euphyllura olivina (Costa)] and the flowers of Malva sylvestris L. favored the survival and/ or reproduction of P. oleae, C. carnea and E. flabellatus. Several plant species such as Daucus carota L., Veronica persica Poir, and Lamium purpureum L. showed to be potential food resources for the studied natural enemies. From the results obtained in this research various applications for managing the olive grove agroecosystem are proposed