Assessing Irish insect diversity via eDNA

In Ireland, there are several insectivorous mammals, such as the lesser horseshoe bat (Rhinolophus hipposideros). R. hipposideros can be found in many regions across the West of Ireland and is protected under Irish and European Law (Wildlife Act 1976; EU Habitats Directive, Annex II). Understanding the diet of this insectivorous mammal allows for informed conservation management decisions to be made while also revealing the role this species plays in the provision of ecosystem services. Traditional approaches to dietary analysis of bat faeces can result in the over-representation of hard bodies insects versus soft-bodies insects. However, DNA metabarcoding approaches, employing next generations sequencing (NGS) facilitates the simultaneous and unambiguous identification of multiple taxa/species from a single DNA extract.
In this study, we used DNA that was extracted from faecal samples collected at R. hipposideros roosts which had been previously sex-typed and individually identified. Using this NGS approach to DNA metabarcoding, the dominant prey groups revealed in the diet were Diptera and Lepidoptera, with Hymenoptera, Coleoptera, Neuroptera and Trichoptera also identified. Pest species such as mosquitoes (Culiseta spp., Culex pipiens) and midges (Culicoides punctatus) implicated in the spread of disease were detected, highlighting the role of R. hipposideros in the provision of ecosystem services relevant to human and animal health.
Using this information, real-time polymerase chain reaction (qPCR) tests were designed to target specific species relevant to human and animal health. Due to the sensitivity of these techniques they can be applied to environmental DNA (eDNA) sources, such as water, to gain a further insight into Irish insect communities.
The combination of these molecular techniques can be used over time to understand insect diversity and their responses to environmental stresses, such as climate change and urbanisation.