Identification of Bioactive Plant Volatiles for the Carob Moth by Means of GC-EAD and GC-Orbitrap MS

• Published in: Applied sciences Vol. 11; no. 18; p. 8603
• Main Authors: Hosseini, Seyed Ali, Goldansaz, Seyed Hossein, Groot, Astrid T., Menken, Steph B. J., Van Der Wielen, Frans, Wissel, Cedric, Vercammen, Joeri, De Rijke, Eva, Roessingh, Peter
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2021
• Subjects: Analytical chemistry; Behavior; Bioactive compounds; Biological activity; biomarkers; Butterflies & moths; Carob; carob moth; Caryophyllene; Chromatography; Electroantennograms; Electron impact; Experiments; Females; Filter paper; Flowers & plants; Fruits; Gas chromatography; GC-EAD; GC-Orbitrap MS; Identification; Insects; Ionization; Males; Mass spectrometry; Mass spectroscopy; Oviposition; Pheromones; Retention; Scientific imaging; Software; Spectral resolution; unknown unknowns; Volatile compounds; Volatiles; Workflow; β-caryophyllene; Middle East; Iran; United States > US; Germany
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app11188603

The aim of this study was to validate a workflow that allows structural identification of plant volatiles that induce a behavioral response in insects. Due to the complexity of plant volatile emissions and the low levels at which these bioactive components tend to occur, gas chromatography-electroantennography (GC-EAD) was applied as the prime differentiator technique, i.e., to indicate particular peaks of interest in the chromatogram. In a next step, the analysis was repeated under identical conditions using GC-Orbitrap mass spectrometry (MS). Combining electron impact (EI) ionization and chemical ionization (CI) with the superior spectral resolution and mass accuracy of the technique enabled straightforward identification of these unknowns, with high confidence in a minute amount of time. Moreover, because of the intrinsic sensitivity of the technique, components that occur at trace amounts but may induce disproportional large behavioral responses are evenly well-identified. We were able to positively identify β-caryophyllene as a bioactive compound in female carob moths. Behavioral attraction was negatively correlated with the amount of β-caryophyllene in host fruits. In an oviposition experiment on filter paper, β-caryophyllene was stimulated in the range of 40–100 ng, while concentrations above 200 ng inhibited oviposition.