Determination of characteristic odorants from Harmonia axyridis beetles using in vivo solid-phase microextraction and multidimensional gas chromatography–mass spectrometry–olfactometry

Abstract

Homeowners, small fruit growers, and wine makers are concerned with noxious compounds released by multicolored Asian ladybird beetles (Harmonia axyridis, Coleoptera: Coccinellidae). A new method based on headspace solid-phase microextraction (HS-SPME) coupled with multidimensional gas chromatography-mass spectrometry-olfactometry (MDGC-MS-O) system was developed for extraction, isolation and simultaneous identification of compounds responsible for the characteristic odor of live H. axyridis. Four methoxypyrazines (MPs) were identified in headspace volatiles of live H. axyridis as those responsible for the characteristic odor: 2,5-dimethyl-3-methoxypyrazine (DMMP), 2-isopropyl-3-methoxypyrazine (IPMP), 2-sec-butyl-3-methoxypyrazine (SBMP), and 2-isobutyl-3-methoxypyrazine (IBMP). To the best of our knowledge this is the first report of H. axyridis releasing DMMP and the first report of this compound being a component of the H. axyridis characteristic odor. Besides the MPs, 34 additional compounds were also identified. Quantification of three MPs (IPMP, SBMP and IBMP) emitted from live H. axyridis were performed using external calibration with HS-SPME and direct injections. A linear relationship (R(2)>0.9951 for all 3 MPs) between MS response and concentration of a standard was observed over a concentration range from 0.1 ng L(-1) to 0.05 microg L(-1) for HS-SPME-GC-MS. The method detection limits (MDL) based on multidimensional GC-MS with narrow heart-cut approach for three MPs were estimated to be between 0.020 and 0.022 ng L(-1). This represents a 38.9-52.4% improvement in sensitivity compared to GC-MS with full heart-cut method. This methodology is applicable for in vivo determination of odor-causing chemicals associated with emissions of volatiles from insects.

Simultaneous determination of eight common odors in natural water body using automatic purge and trap coupled to gas chromatography with mass spectrometry

“…These two techniques are simple, fast, inexpensive, portable, and solvent-free. SPME has excellent exhibition in analyzing DMTS, IPMP, IBMP, MIB, GSM, ␤-cyclocitral, and ␤-ionone [39][40][41][42]. However, choosing a fiber suitable for large-scale analysis of odors is difficult [25,[42][43][44][45], sensitivity is very low for lowboiling-point odors such as DMS [42].…”

Uso de semioquímicos en el control de plagas. Estudios básicos y de aplicación

“…New medfly volatiles, not previously reported in the literature, were identified in the present study, which confirms that SPME is adequate to investigate insect volatile compounds as reported for other species (Cai et al, 2007;Arakaki et al, 2009;Robacker et al, 2009). …”

“…La técnica de SPME ha sido empleada principalmente para estudios en coleópteros (Said et al, 2003;Cai et al, 2007;Yasui et al, 2008;Arakaki et al, 2009), y recientemente para la identificación de sustancias emitidas por el tefrítido Anastrepha serpentina (Wiedemann) (Robacker et al, 2009). …”

“…SPME-gas chromatography (GC) was first applied in 1995 as an alternative method for the study of airborne insect pheromones (Malosse et al, 1995), and since then, SPME has been employed in sampling of insect volatiles, particularly in beetles (Said et al, 2003;Cai et al, 2007;Yasui et al, 2008;Arakaki et al, 2009). SPME has also been recently employed in the identification of chemicals emitted by Anastrepha serpentine (Robacker et al, 2009), but its use in medfly volatile collection has not yet been reported, as far as we know.…”

Fast-GC Quantification of Harmonine, the Major Defense Alkaloid of the Multicolored Asian Ladybird <i>Harmonia axyridis</i>(Pallas)

“…The direct impact of this feeding has not yet been quantified but this behavior is still problematic especially if fruits are meant to be pressed. When crushed with fruits, ladybirds release methoxypyrazines, alkaloids and other contaminants with low perception thresholds altering the quality of the product [5][6][7].…”