Overview
Suspended traps such as Lindgren funnel traps and vane traps are increasingly used in combination with DNA metabarcoding to characterise canopy arthropod communities. Despite their wide use, it remains unclear how different preservatives and storage conditions affect DNA integrity in samples destined for molecular analysis. Ethanol, while commonly used as a preservative, poses several challenges for field deployment: it is volatile, expensive and unsuitable for passive trapping because it is known to attract some insects. Monopropylene glycol (MPG) has emerged as a practical alternative: it is non-toxic, affordable, easy to handle and transport and preserves specimen morphology for identification. However, its effect on DNA preservation, especially when diluted by rainwater in the field or during storage, remains poorly understood.
This study uses insect mock communities of low (6 species) and high (12 species) diversity to test the effects of preservation method, storage duration and ethanol transfer on species detection via lysis buffer-based non-destructive DNA metabarcoding. Mock communities were processed with metabarcoding over time after being stored in undiluted MPG stored at 5°C, diluted MPG stored at 5°C and absolute ethanol stored at −18°C as the optimal reference treatment. Community composition recovered was significantly influenced by preservation method and the diversity of the mock community. On the other hand, the effects of storage time and transfer were significant only in low diversity mock communities, and detection rates varied across species.
Overall, results confirmed that MPG is a suitable and effective fixative for short-to medium-term storage at 5°C, even when diluted, maintaining DNA integrity for metabarcoding applications. These findings are consistent with prior studies and provide further support for MPG as a viable alternative to ethanol in arthropod biomonitoring and research.