Essential Oils as Post-Harvest Crop Protectants against the Fruit FlyDrosophila suzukii: Bioactivity and Organoleptic Profile

Simple Summary The spotted-wing drosophilaDrosophila suzukiiis an invasive small fruit fly that causes extensive damage to many fruit crops. To control this pest, the use of aromatic plants essential oils (EOs) is gaining importance since they are bioactive, biodegradable, and ecologically safe. However, despite of the EOs proved efficacy, they still do not have a widespread application due to their high volatility, composition variability and especially their strong smell. In this study we evaluated not only the EOs bioactivity but also their effects on the organoleptic profile of treated fruits. We tested two EOs extracted from mandarin (Citrus reticulata) and tea tree (Melaleuca alternifolia) very different for composition and smell. Both the EOs were effective in repellingD. suzukii. However, while no negative effects on the organoleptic profiles were detected for the fruits treated withCitrus reticulataEO, the fruits treated withM. alternifoliaEO were defined by the panel of experts as not suitable for consumption. Overall, our findings indicate that the use of EOs for the post-harvest protection of small fruits is feasible, provided that the EOs have been selected not only for their bioactivity against the insect pest but also for their affinity with the consumers' sensorial system. The essential oils extracted from mandarin (Citrus reticulataBlanco) fruits, and from tea tree (Maleleuca alternifolia(Maiden and Betche) Cheel) leaves have been chemically analyzed and tested for their bioactivity againstD. suzukii. Besides, to estimate consumers' acceptability of the essential oil (EO) treatments, we evaluated their impact on the organoleptic characteristics of the EO-treated fruits. The main chemical constituents of the two EOs were 1,8-cineole and 4-terpineol forM. alternifolia(22.4% and 17.6% of the total components, respectively), and limonene (83.6% of the total components) forC. reticulata. The behavioral tests indicate that the two EOs are able to deterD. suzukiioviposition and thatD. suzukiishows positive chemotaxis to low concentrations of the EOs and negative chemotaxis when the EO concentration increases. While no negative effects on the organoleptic profiles were detected for fruits treated withC. reticulataEO, the olfactory profile of fruits treated withM. alternifoliaEO was so negative that they were defined as not suitable for consumption by panellists. Overall, our findings indicate that the use of EOs for the post-harvest protection of small fruits is feasible, provided that the essential oils are selected not only for their bioactivity against the insect pest but also for their affinity with the consumers' sensorial system.