Trap nests for bees and wasps to analyse trophic interactions in changing environments-A systematic overview and user guide

Abstract

1. Trap nests are artificially made nesting resources for solitary cavity‐nesting bees and wasps and allow easy quantification of multiple trophic interactions between bees, wasps, their food objects and natural enemies. 2. We synthesized all trap nest studies available in the ISI Web of Science™ to provide a comprehensive overview of trap nest research and identify common practical challenges and promising future research directions. 3. Trap nests have been used on all continents and across climate zones and publication numbers have increased exponentially since the first studies in the 1950s. Originally used for detailed exploratory natural history observations, trap nests are now also an established method in hypothesis‐driven ecology and to assess environmental changes. We identify the potential of trap nests for environmental monitoring by assessing trophic interaction networks of the groups involved. While pollen collection by bees or prey hunting by wasps has often been addressed, and interactions with natural enemies were included in almost half of all publications, surprisingly few studies have quantified trophic interaction networks in response to natural and anthropogenic environmental changes. 4. By simultaneously revealing a multitude of trophic interactions, trap nests have the potential to broaden our understanding how species interaction networks are influenced by manifold environmental changes, which are pressing topics in ecological research. To foster the use of trap nests in future studies, we identify common challenges and offer guidance on practical solutions.