Pellets of proof: First glimpse of the dietary composition of adult odonates as revealed by metabarcoding of feces

Abstract

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.

Agriculture shapes the trophic niche of a bat preying on multiple pest arthropods across Europe: Evidence from DNA metabarcoding

“…Order‐level taxonomy was assigned at >95% identity values, family‐level taxonomy at >96.5%, and species‐level taxonomy was assigned when the identity values between the query and reference sequences were above 98%, following Alberdi et al., ;. Species‐level identification was only performed using the Zeale data set due to the low reliability of Epp sequences for species‐level taxonomic identification (Alberdi et al., ; Kaunisto, Roslin, Sääksjärvi, & Vesterinen, ). All identified species were manually checked, and species‐level assignment was restricted only to species known to be present at each sampling region.…”

Finding flies in the mushroom soup: Host specificity of fungus‐associated communities revisited with a novel molecular method

“…(), Alberdi, Aizpurua, Gilbert, and Bohmann () and Kaunisto et al. (), we refrained from measuring the DNA concentration of individual libraries and instead pooled 2.5 μl of each indexed sample per sequencing run (i.e., each pool consisted of samples amplified with either COI or ITS+16S primers), then cleaned pools using dual SPRI purification to remove any possible artefacts or nontarget size amplicons (Wirta et al., ). Sequencing was performed on an Illumina MiSeq platform at the Functional Genomics Unit of the University of Helsinki, Finland.…”

“…In terms of links, metabarcoding allows us to study a wide variety of different interactions, such as pollination, predation or symbiosis (Clare, ; Roslin & Majaneva, ). In terms of the architecture of such links, metabarcoding allows us to study a wide range of aspects, ranging from diet composition of individual species (Kaunisto, Roslin, Sääksjärvi, & Vesterinen, ; Vesterinen et al., ) through host specificity of particular guilds or food web modules (Baker, Bittleston, Sanders, & Pierce, ) to community‐level structuring of trophic interactions (Geisen, Laros, Vizcaíno, Bonkowski, & De Groot, ; Wirta et al., ).…”

From feces to data: A metabarcoding method for analyzing consumed and available prey in a bird‐insect food web

“…With advances in sequencing technologies, detecting prey DNA from predator feces has recently become a norm in diet studies of many insectivorous animals (e.g., Clare et al, 2009;Wirta et al, 2015;Kaunisto et al, 2017;Vesterinen et al, 2018). As both nestling feces and insect frass can be collected easily using harmless and unobtrusive methods, this methodology is ideal for many applications.…”