APL009

APL009_Hornet_Nests_PyGCMS

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Molecular characterization of Asian hornet paper envelope nests

By Joeri Kaal and Luis Rodríguez-Lado

Abstract 

We explored the potential of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) as a molecular characterization tool for paper envelop materials in nests of the Asian hornet (Vespa velutina Lepeletier, 1836), a runaway invasive species in Western Europe. The area of study is the NW of the Iberian Peninsula (Galicia, A Coruña province) and the main tree types of the vegetation in the sampled areas are pine, eucalypt and oak, with a smaller abundance of chestnut and fruit trees. The objective was to determine whether molecular fingerprinting in combination with the information on vegetation patterns allows to determine the origin of the decaying wood fibres used for nest construction, and thereby determine the insects’ preferences for raw material. The results confirm that the envelopes consist predominantly of polysaccharides and lignin, and that especially the lignin composition is useful for tracking vegetation sources of raw materials. The relationships between dominant vegetation and nest composition was smaller than expected and there seems to be no clear preference for a given tree type, in spite of very large inter-nest variation in the balance between guaiacyl and syringol lignin products (S/G ranging between 0.0 and 3.0). Thus, the Asian hornet does not exhibit a specific preference for a particular type of vegetation. Instead, it adapts to the available materials in its environment and uses them conveniently in nest construction. This highlights the high flexibility of the Asian wasp in utilizing the resources of the environment it colonizes. However, remarkable intra-nest variation in both colour and S/G ratio indicates that nest colour banding is related to raw material selection. This study contributes to a better understanding of the behavior of V. velutina, which, in turn, helps define appropriate actions to limit its expansion.

Keywords: Asian hornet; paper nest envelopes; molecular characterization; Py-GC-MS; insect ecology.

ISSN: 2659-5605 (Analytical Pyrolysis Letters)

 

 

APL008

APL008
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Towards understanding ecological disaster in the Harz Mountains (Central Germany) by carbon tracing: pyrolysis-GC-MS of biological tissues and their water-extractable organic matter (WEOM)

By Joeri Kaal, César Plaza, Marta Pérez-Rodríguez and Harald Biester

Abstract 

Streams and reservoirs in the Harz National Park experience high dissolved organic matter (DOM) concentrations, the cause of which is unknown. We studied potential sources of DOM by means of pyrolysis-GC-MS (Py-GC-MS). The biological materials include vegetation samples (spruce, birch, blueberry, heather, sedge, grass, peat moss, epiphytic moss), microbial sources (epilithic biofilm, lichen, fungi) and excremental fabric. In addition to ground biological samples (bulk organic matter; BOM), their leachates (water extraction of BOM samples followed by filtration; WEOM) were analyzed, to obtain knowledge on solid-liquid transfer effects. Results of BOM showed potential for molecular provenancing on the basis of relative proportions of major biopolymers (lignin, polysaccharides, tannin, resin, etc.) and specific products (biomarkers). Even though WEOM had lower molecular diversity than BOM, identified molecular features of WEOM can be useful to identify potential sources of environmental DOM. Unsubstituted guaiacol prevails among the pyrolysis products of the WEOM of spruce samples (especially wood), which probably originates from pyrolytically decarboxylated vanillic acid moieties. The other plant materials produced a more diverse fingerprint of phenols, guaiacols and syringols, which can be used to distinguish gymnosperm-derived DOM, peatland vegetation and angiosperm trees and shrubs. Several other O-containing moieties such as benzoic acids, benzaldehydes and indanones (not present in BOM) were also frequent products of WEOM. These results lay the foundation for future interpretations of environmental DOM samples’ molecular fingerprints.

Keywords: Harz Mountains; dissolved organic matter; Py-GCMS; biological sources.

ISSN: 2659-5605 (Analytical Pyrolysis Letters)