Environmental DNA metabarcoding of pan-trap water to identify arthropods
and the plants they interact with
Abstract
Globally, the diversity of arthropods and the plants upon which they
rely are under increasing pressure due to a combination of biotic and
abiotic anthropogenic stressors. Unfortunately, conventional survey
methods used to monitor ecosystems are often challenging to conduct at
large scales. Pan traps are a commonly used pollinator survey method and
environmental DNA (eDNA) metabarcoding of pan-trap water may offer a
high-throughput alternative to aid in the detection of both arthropods
and the plant resources they rely on. Here, we examined if eDNA
metabarcoding can be used to identify arthropod and plant species from
pan-trap water, and invesitigated the effect of different DNA extraction
methods. We then compared plant species identified by metabarcoding with
observation-based floral surveys and also assessed the contribution of
airborne plant DNA (plant DNA not carried by arthropods) using marble
traps to reduce putative false positives in the pan trap dataset.
Arthropod eDNA was only detected in 17% of pan trap samples and there
was minimal overlap between the eDNA results and morphological
identifications. In contrast, for plants, we detected 64 taxa, of which
53 were unique to the eDNA dataset, and no differences were identified
between the two extraction kits. We were able to significantly reduce
the contribution of airborne plant DNA to the final dataset using marble
traps. This study demonstrates that eDNA metabarcoding of pan-trap water
can detect plant resources used by arthropods and highlights the
potential for eDNA metabarcoding to be applied to investigations of
plant-animal interactions.