Arthropod detections from eDNA metabarcoding of flower filtrate and DNA derived from bulk samples of insects

We compared pollinator diversity derived from environmental DNA (eDNA) extracted from flowers and DNA extracted from pulverized bulk samples of insects collected from vane traps deployed at the same sites. We used three metabarcoding primers, two of which target arthropods generally (COI-Jusino and 16S-Marquina) and one that targets bumblebees (Bombus spp., COI-Milam). Across methods, we detected 77 insect families from 9 orders. The COI-Jusino marker amplified the highest taxonomic diversity compared to 16S-Marquina and COI-Milam. More ASVs were recovered from vane traps (blue: 1357, yellow: 1542) than flowers (245), but only 23% of families and 13% of genera were shared among methods, indicating that flowers and blue and yellow vane traps may each sample different parts of the available arthropod community. Of 29 flowers with known bee visitations, only 10 had bee detections, and incomplete reference databases hindered assignment to species.