Environmental DNA metabarcoding of cow dung reveals taxonomic and functional diversity of invertebrate assemblages

Insects and other terrestrial invertebrates are declining in species richness and abundance. This includes the invertebrates associated with herbivore dung, which have been negatively affected by grazing abandonment and the progressive loss of large herbivores since the Late Pleistocene. Importantly, traditional monitoring of these invertebrates is time-consuming and requires considerable taxonomic expertise, which is becoming increasingly scarce. In this study, we investigated the potential of environmental DNA (eDNA) metabarcoding of cow dung samples for biomonitoring of dung-associated invertebrates. From eight cow pats we recovered eDNA from 12 orders, 29 families, and at least 54 species of invertebrates (mostly insects), representing several functional groups. Furthermore, species compositions differed between the three sampled habitats of dry grassland, meadow, and forest. These differences were in accordance with the species' ecology; for instance, several species known to be associated with humid conditions or lower temperatures were found only in the forest habitat. We discuss potential caveats of the method, as well as directions for future study and perspectives for implementation in research and monitoring.Funding provided by: CarlsbergfondetCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100002808Award Number: CF18-0949Funding provided by: Faculty of Natural Sciences, Aarhus University*Crossref Funder Registry ID: Award Number: Funding provided by: CarlsbergfondetCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100002808Award Number: CF16-0005Funding provided by: Villum FondenCrossref Funder Registry ID: http://dx.doi.org/10.13039/100008398Award Number: 16549Funding provided by: 15. Juni Fonden*Crossref Funder Registry ID: Award Number: 2017-N-10Funding provided by: Faculty of Natural Sciences, Aarhus UniversityCrossref Funder Registry ID: Funding provided by: 15. Juni FondenCrossref Funder Registry ID: http://dx.doi.org/NoneAward Number: 2017-N-1