Field evaluation of the susceptibility of olive cultivars to Bactrocera oleae in Western Crete (Southern Greece)

Abstract: The susceptibility of 27 olive cultivars to Bactrocera oleae (Rossi) from the major European Mediterranean olive-producing countries, was evaluated during two consecutive years, under field conditions of western Crete (Southern Greece), where environmental conditions are largely favorable for the reproduction and development of its population. Olives were collected from the National Olive Germplasm Bank of Greece of the Institute of Olive Tree, Subtropical Crops & Viticulture, Hellenic Agricultural Organization (ELGO-DIMITRA) in Chania. The samples (one hundred olives per cultivar per date) were collected every fortnight at eight different times during fruit ripening, from June to October, during 2019 and 2020. The observations were carried out by detecting the sterile oviposition stings, alive preimaginal stages (eggs, larvae and pupae), dead preimaginal stages (larvae and pupae) and emergence holes. The results of this study confirm that female olive fruit flies exhibited a strong ovipositional preference when presented with a choice of olive cultivars in the field. Among the olive cultivar tested, ‘Manzanilla Isr’. ‘Manzanilla’ and ‘Konservolia’ were the most heavily infested during the two consecutive years. The next most heavily infested were ‘Picual’, ‘San Francesco’, ‘Valanolia’ ‘Frantoio Rodou’, Frantoio’ and ‘San Agostino’ while ‘Kalamon’, ‘Koroneiki’, ‘Tragolia’, ‘Pikrolia’, ‘Mavrelia’, ‘Rachati’, ‘Myrtolia’, ‘Koutsourelia’ and ‘Thiaki’ show the lowest susceptibility to olive fruit fly attacks. Even though the olive fruit fly damaged all tested cultivars those showing indications of relative resistance could be tested for their suitability in new plantations in areas with high B. oleae populations as well as to be employed as prebreeding material.