Sensory Perception of Six Essential Oils in Humans and Tenebrio molitor: Relationship with Volatile Compound Physicochemical Properties

Olfactory detection of essential oils (EOs), natural plant-derived mixtures of odorous volatile compounds, stimulates neural pathways involved in emotion, cognitive function, and memory in humans and significantly influences insect behavior (inducing attractiveness or repellency). In this study, the olfactory perception of rose (EO 1, a synthetic mixture with rose aroma), eucalyptus (EO 2), lemon (EO 3), clove (EO 4), rosemary (EO 5), and caraway (EO 6) EOs in untrained human participants was compared to the behavioral responses induced in Tenebrio molitor (adult insects) by EO exposure. Significant differences emerged in the perception of EO odor dimensions (pleasantness, intensity, and familiarity) using a Likert-type scale in untrained participants. The tested EOs elicited different behavioral responses in T. molitor insects, as assessed by repellency, escape, and choice tests. A positive correlation (r = 0.7861, p < 0.05) emerged between EO odor intensity perceived by participants and escape induction in T. molitor adults. GC–MS analysis revealed citronellol, 1,8-cineole, limonene, eugenol, α-pinene, and carvone as the most abundant volatile compounds in EO 1, EO 2, EO 3, EO 4, EO 5, and EO 6, respectively. The EO odor dimensions in participants and insect behavioral responses were also related to the in silico physicochemical/pharmacokinetic properties of the main EO components. Our results provide new insights into the chemical basis of olfactory preferences both in T. molitor adults and humans.