DNA barcoding resolves quantitative multi-trophic interaction networks and reveals pest species in trap nests

Abstract

Insects, as one of the most species-rich taxa with enormous taxonomic, behavioural and functional diversity, are in decline. Bees and wasps are especially crucial for ecosystems as pollinators or to control populations of other insects. To understand population drivers, comprehensive knowledge about top-down and bottom-up interactions, including all interaction partners, is needed. Nests of trap-nesting bees and wasps include multi-trophic interactions between bees, wasps, their food resources and natural enemies, simultaneously, however, up to today, all trophic interactions are not yet included in trap nest research because of challenges to identify the food used by nesting bees and wasps. Here, we reconstructed quantitative three- and four-trophic interaction networks of species in three apoid wasp families using DNA barcoding. The obtained tripartite and quadripartite networks encompassed natural enemy-wasp-spider and natural enemy-wasp-herbivore-plant interactions. Moreover, we identified so far undescribed Hymenoptera-prey interactions, including prey species known as agricultural and forest pests. More extensive research on bee and wasp multitrophic interaction networks will provide valuable insights to better understand responses to environmental and biodiversity change, to investigate ecological theory and to reveal so far unknown feeding links.