Natural enemy complex of Bactrocera oleae in organic and conventional olive groves

Abstract: Around the Mediterranean Basin Bactrocera oleae (Rossi) (Diptera: Tephritidae) is attacked by a complex of natural enemies. The percentage of parasitism as well as the natural enemy complex of B. oleae in organic and conventional olive groves, located in Chania (west Crete) and in Kyparissia (w. Peloponnesus) of Greece, were studied during three successive years from 2010-2012. During the experimental period four parasitoids and one predator attacked olive fruit fly immature stages and eggs, respectively. In Crete, in 2010 the most abundant was the ectoparasitoid Eupelmus urozonus followed by the predator Prolasioptera berlesiana and the endoparasitoid Psyttalia concolor, while the ectoparasitoid Eurytoma martelli was less abundant. In 2011 the most abundant were E. urozonus and Pnigalio mediterraneus followed by P. concolor and in 2012 the most abundant was P. concolor. In the area of Kyparissia in autumn 2012 the only parasitoid recorded was E. urozonus. In general, the parasitization rates in organic as well as in conventional olive groves was significantly fluctuated depending on the year and the locality. Although higher rates of parasitism were recorded in organic olive groves, no significant differences were observed regarding total parasitism rates between organic and conventional olive groves. In spite of the application of poisonous bait sprays against B. oleae in the conventional groves, population of its natural enemies showed high densities and it was not significantly different from the population in the organic groves.