Data from: Pellets of proof: first glimpse of the dietary composition of adult odonates as revealed by metabarcoding of feces

Recent advances in molecular techniques allow us to resolve the diet of
unstudied taxa. Odonates are potentially important top-down regulators of
many insects. Yet, to date, our knowledge of odonate prey use is based
mainly on limited observations of odonates catching or eating their prey.
In this study, we examine the potential use of metabarcoding in
establishing the diet of three adult odonate species (Lestes sponsa,
Enallagma cyathigerum, and Sympetrum danae) at a site in southwestern
Finland. To this purpose, we compared three different methods for
extracting DNA from fecal samples: the Macherey-Nagel Nucleospin XS kit, a
traditional salt extraction, and the Zymo Research Fecal Microprep kit.
From these extracts, we amplified group-specific mitochondrial markers
(COI and 16S rRNA) from altogether 72 odonate individuals, and compared
them to comprehensive reference libraries. The three odonate species show
major overlap in diet, with no significant differences between individuals
of different size and/or gender, reflecting opportunistic foraging of
adult odonates. Of a total of 41 different prey species detected, the most
frequently consumed ones were Diptera, with additional records of six
other orders. Based on our data, the best DNA extraction method is the
traditional salt extraction, as it provides the most information on prey
content while also being the most economical. To our knowledge, this is
the first study to resolve the species-level diet of adult odonates. Armed
with the appropriate methodological caveats, we are ready to examine the
ecological role of odonates in both terrestrial and aquatic food webs, and
in transferring subsidies between these two realms.