# The Infestation of Olive Fruits by _Bactrocera oleae_ ([PERSON])
## 1 Introduction  
Virgin olive oil (VOO) has an exceptional aroma and flavor that distinguishes it from other vegetable oils. The assessment of these two properties by means of a specific sensory analysis is an essential requirement for the commercial classification of virgin olive oils [1]. For this purpose, expert tasters evaluate the green and fruits aroma notes, typical of freshly extracted VOO, and the intensity of the bitter and pungent taste notes of the oils. Volatile and phenolic compounds are responsible for these aroma and taste notes [2, 3]. Both types of compounds are produced during the industrial oil extraction process as a consequence of the destruction of the cellular integrity of the olive fruit that triggers a number of biochemical reactions. The volatile and phenolic content of VOO is genetically determined but it is also affected by a number of factors, such as the ripening index of the olive fruit, the geographical origin and the climatic conditions, the technological parameters used during the extraction process, and also the storage time and conditions [4, 5, 6, 7]. It is important to point out that phenolic compounds not only determine the flavor of the VOO, since due to their antioxidant activity they also contribute to its well-known health benefits and improve the oxidative stability of the oils by reducing lipid peroxidation [8, 9]. In addition to being decisive for the organoleptic properties of VOO, both volatile and phenolic compounds are involved in the plant's natural defense mechanisms. This is why their biosynthesis pathways are especially affected by different abiotic (salinity, drought, extreme temperatures) and biotic factors (insets, bacteria, fungi, or viruses) [10, 11]. Three decades have passed since we reported [2] that the main volatile compounds responsible for the unique aroma of VOO are synthesized when enzymes from the lipoxygenase (LOX) pathway and their substrates, linoleic (LA) and linoleic acids (LNA), come into contact during the olive fruit milling in the first stage of the oil extraction process. LOX catalyzes the production of 13-hydroperoxide derivatives in the first step of this pathway, which are later cleaved heterolytically by the hydroperoxide lyase (HPL) enzyme, forming six straight-chain carbons (C6) aldehydes [12] that are reduced by alcohol dehydrogenase enzymes to C6 alcohols, and finally these alcohols are converted into the corresponding esters by alcohol acyltransferase enzymes [2]. C6 aldehydes and alcohols, and their derived esters, associated with green and fruity odor notes, are the key compounds in VOO aroma. Additionally, the contribution of compounds with five straight-chain carbons (C5 compounds), formed through an additional branch of the LOX pathway, to the aroma of VOO has also been proved [13]. Many compounds formed through the LOX pathway, globally known as oxylipins, exhibit strong biological activities and play important roles in the defense mechanisms of plants, both activating and regulating various defense responses by inducing genes related to other key biochemical pathways, and also in the immediate response to pathogens attacks through the antimicrobial activity of C6-aldehydes and esters [14; 15]. The phenolic composition of VOO is directly related to the content of phenolic glucosides initially present in the olive fruit, such as the secoiridoids oleuropein, ligstroside, and demethyloleuropein, whose contents are genetically determined but modulated by environmental and physiological factors, or as a consequence of biotic and abiotic stresses [16]. The phenolic glucosides of the olive fruit are substrates of different enzymes during the oil extraction process [17].