Deciphering How Olive Volatiles and Fatty Acids Shape Bactrocera oleae (Rosii) Oviposition Preference Using Multivariate Regression Models

Abstract

The olive fly (Bactrocera oleae (Rossi)), the major pest of olives, primarily recognises visual, olfactory, acoustic, gustatory and tactile signals that regulate its behavioural activity, courtship and reproductive success, as well as the search for ideal conditions for its offspring. Recent studies highlight the importance of chemical compounds present in olive fruits, particularly volatile organic compounds (VOCs), in these processes. This paper aims to further explore the relationships between B. oleae and specific chemical traits in fresh sound fruits that might trigger and enhance infestations, namely VOCs, their precursors (fatty acids) and lipidic antioxidants (tocopherols). The study has been performed within the framework of a table olive cross-breeding program in order to develop predictive models to identify genotypes less susceptible to olive fly infestation. Significant differences in chemical traits were observed among the genotypes studied, highlighting their role in oviposition preference of the olive fly. ‘Hojiblanca’ and ‘Kalamon’, known for their lower susceptibility, stood out for their high concentrations of D-limonene among the 33 identified VOCs and low saturated fatty acid content. Specific VOCs like α-pinene, copaene, nonanal and o-xylene, along with some minor fatty acids, were key predictors for developing multivariate models that estimate susceptibility to olive fly oviposition.