ISHS Acta Horticulturae 791: V International Symposium on Olive Growing
ENTOMOLOGICAL SURVEY WITHIN THE ECOSYSTEM OF AN OLIVE ORCHARD IN SOUTHERN PORTUGAL (ALGARVE) |
| Authors: | L. Almeida, C. Calado, A. Gonçalves, A. Neves |
| Keywords: | olive tree, Prays oleae, Bactrocera oleae, parasitoids, Ageniaspis fuscicollis |
| Abstract:
The olive tree (Olea europea L.) is an important crop in Portugal, occupying an area of more than 300,000 ha. Traditionally, olive trees were associated with annual legume or cereal crops, or pastures. The trees were spaced 8–12 meters apart and no pest control was done. Nowadays, cultural practices are changing. The need of an increased productivity and better quality comes along with higher tree density, fertilization and mechanization. Pests and diseases are heavily controlled with chemicals without respect for eventual existing pest-parasitoid/predator relationships. This study is an attempt to verify the existence of those relationships in an undisturbed olive ecosystem in the south of Portugal. The population dynamics of two main olive pests in Portugal, Prays oleae Bern. and Bactrocera oleae Gmelin. were studied as well as oviposition sites and the auxiliary entomofauna, especially in what concerns the parasitoids, related to P. oleae. Sexual pheromone and yellow cromotropic traps were used and leaves, small twigs and olive fruits were collected and maintained in a growth chamber (T:24±1°C; H:70%±5%; 16hL;8hD) to observe existing parasitoids. Results show the occurrence of three peaks (March, May and September) for P. oleae, corresponding to the three characteristic generations of this pest and a preference of the East sector of the tree for egg-laying during the fruit generation. Four families of Hymenoptera were identified (Braconidae, Ichneumonidae, Elasmidae and Encyrtidae), recognized as important on the control of P. oleae. The species Ageniaspis fuscicolis (Hym. Encyrtidae) was dominant, being present from May to November. Regarding the presence of B. oleae, it fluctuated between May and November with a peak during the third week of August. | |
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