Selective feeding and niche differentiation in adult boreal Odonata revealed by DNA metabarcoding

Abstract Diet choice plays a key role in shaping species interactions, trophic dynamics and ecosystem function, yet the extent to which insect meso‐predators exhibit dietary specialisation and prey selection remains poorly understood. Understanding how meso‐predators partition resources and respond to prey availability is therefore important for interpreting food web structure and ecosystem dynamics. Here, we explore whether the dietary habits of three sympatric Odonata species, the dragonfly Libellula quadrimaculata and the damselflies Erythromma najas and Coenagrion hastulatum , inhabiting boreal floodplain wetlands in central Sweden, reflect environmental prey availability or exhibit evidence of selective foraging. Additionally, we investigate whether species‐specific foraging strategies influence diet breadth and selectivity, and if odonates disproportionately consume biting Diptera of public‐health concern relative to their environmental availability. We predicted that opportunistic feeding would result in diets reflecting prey abundance, that actively hawking species would exhibit broader and less selective diets than perch‐hunting species and that Culicidae would form only a minor component of the diet. Using COI metabarcoding of faecal pellets alongside arthropod sampling from Malaise and emergence traps, this study provides new insights into fine‐scale trophic interactions. Overall, the three species were relatively opportunistic, yet suggestions of diet selection are present. Diptera dominated the diet of all three species, with Chironomidae most abundant and mosquitoes (Culicidae) only a minor component. This indicates that odonates did not disproportionately consume prey of ecological or public‐health significance relative to their environmental availability. The largest species, L. quadrimaculata , with a more hawker‐like foraging strategy, exhibited greater dietary variance in NMDS space than the smaller damselflies, suggesting size‐ and strategy‐dependent differences in prey use. Taxonomic richness differed significantly between L. quadrimaculata and the two damselflies, which did not differ from each other, while Shannon diversity and Evenness were similar across species. Comparisons with prey availability revealed indications of deviations from random feeding. Jacobs' D values signalled consistent prey selectivity in all three species, with preference for Ephemeroptera and avoidance of Diptera. This study indicates the first molecular evidence of selective feeding in Odonata and suggests that species‐specific traits shape trophic interactions and dietary niches in boreal wetlands.