Context. Globally, insectivorous bats are important moderators of insect populations, including agricultural pests. However, in human-modified environments, changes to insect diversity and abundance may have detrimental impacts on bat populations. The southern bent-wing bat (SBWB; Miniopterus orianae bassanii), is a critically endangered, cave-dwelling bat with a restricted distribution across south-eastern Australia, an area now dominated by agricultural land uses. Understanding SBWB diet may highlight the role of bats in influencing insect populations in surrounding agricultural land, while simultaneously providing crucial data for conservation management of this critically endangered species.
Aim. To investigate the SBWB’s diet using arthropod DNA metabarcoding of scats and guano collected from seven caves across the species’ range.
Methods. We collected scats from bat roosts and from guano piles on cave floors during late summer and early autumn of 2019. We used PCR to amplify two short, overlapping arthropod mtDNA cytochrome oxidase subunit 1 barcodes and sequenced these using the Illumina MiSeq to identify arthropod diet species.
Key results. Moths (order Lepidoptera) were the most prevalent insect identified in all samples and from all sites. Many of the 67 moth species identified were associated with agricultural land use (e.g. pasture webworm (Hednota pedionoma) and armyworm (Persectania dyscrita)), and several, including the bogong moth (Agrotis infusa), are migratory, suggesting the SBWB’s diet changes seasonally.
Conclusion. By describing the diet of the SBWB, we have fulfilled one recommendation of the national recovery plan for the species. The SBWB preys predominantly on moths, and its diet has likely been impacted by the increase in agricultural land use across its range. Further research is required to understand its foraging habitat requirements.
Implications. Our findings suggest the SBWB may play a role in controlling populations of moth species considered to be agricultural pests. The wide variety of moths consumed by SBWBs could afford the species some resilience to landscape changes affecting moth assemblages. The methodological framework developed here could be applied to investigate how land-use changes may contribute to bat population declines, but also how insectivorous bats may provide important ecosystem services by controlling pest insect species in modified landscapes.
