From Culinary Laurel to Foodborne Chagas Risk Exploring the Insecticidal Effects of Laurus nobilis Essential Oil

Bay laurel (Laurus nobilis L.) is a widely used culinary herb whose essential oil has attracted interest in food science for its aromatic constituents and potential preservative properties. Beyond these applications, the bioactivity of its volatiles merits investigation in the context of foodborne Chagas disease, which can result from consumption of foods or beverages contaminated with Trypanosoma cruzi carried by infected triatomines or their excreta. This study characterized L. nobilis leaf essential oil (LNEO), evaluated its contact insecticidal activity against fifth-instar Rhodnius prolixus nymphs, and compared the volatile profiles associated with treated and untreated insects. LNEO was obtained from 200 g of leaves by Clevenger hydrodistillation for 2 h (0.8% yield) and characterized by gas chromatography–mass spectrometry (GC–MS). For contact assays, 50 µL of LNEO was applied to filter paper lining Petri dishes. Each condition comprised six replicates of ten randomly selected nymphs, with corresponding untreated controls, and experiments were conducted at least twice. After freezing, headspace volatiles from three insects per condition were collected by solid-phase microextraction (HS-SPME) and analyzed by GC–MS. Compounds were tentatively identified using mass spectra, chromatographic retention information, and Wiley library matches. Results were expressed as relative chromatographic peak areas. The LNEO contained 1,8-cineole as its major constituent (37–42%) and caused 80% mortality following contact exposure. Headspace analysis revealed additional differences between groups: acetoin accounted for approximately 7% of the selected volatile profile in treated insects, whereas acetic acid (12%) and 2-methylbutanal (7%) were prominent in controls. These findings are particularly relevant to insect chemical ecology because acetic acid has been identified in Brindley’s gland secretions of R. prolixus and investigated in the context of chemical communication. Its occurrence in the control profile provides a biologically meaningful point of reference. The distinct volatile patterns observed alongside insect mortality demonstrate how HS-SPME/GC–MS can complement conventional bioassays by capturing exposure-associated chemical signatures. By linking the chemistry of a food-relevant aromatic plant with insecticidal effects and insect-associated volatiles, this study identifies a promising direction for exploring laurel-derived compounds in triatomine management and research relevant to the prevention of foodborne Chagas disease. The authors thank CNPq PROEP, Universidade Federal do Amazonas (UFAM) and FAPEAM for financial support.