One bat’s waste is another man’s treasure: a DNA metabarcoding approach for the assessment of biodiversity and ecosystem services in Ireland using bat faeces

Arthropod populations are constantly changing due to changes in climate and the globalisation of trade and travel. Effective and diverse monitoring techniques are required to understand these changes. DNA metabarcoding has facilitated the development of a broad monitoring method to sample arthropod diversity from environmental and faecal samples. In this study, we applied DNA metabarcoding to DNA extracted from bat faecal pellets collected in Ireland from the lesser horseshoe bat, Rhinolophus hipposideros, a protected bat species of conservation concern in Europe. From as few as 24 bat faecal pellets, we detected 161 arthropod species from 11 orders, including 38 pest species of which five were determined to be priority pests, highlighting potential ecosystem services provided by R. hipposideros which are important for the functioning of healthy ecosystems. We also report the potential identification of 14 species not previously recorded in Ireland, but upon further investigation found that many of these could have been misidentified due to inadequacies in the genetic reference database. Despite the small sample size, we found that male and female diets did not differ significantly. However, sampling location did explain variation within the diet, highlighting how landscape features influence arthropod composition and diversity. We discuss the current limitations of the methodology in Ireland, how these can be overcome in future studies, and how this data can be used for biodiversity monitoring and informing conservation management of protected bat species.