Resin foraging interactions in stingless bees: an ecological synthesis using multilayer networks

Stingless bees use resins for nest construction, colony defense, and production of cerumen, propolis, and geopropolis. Despite their importance, resin foraging interactions are neglected in stingless bee ecology, so a synthesis is required to map how much we currently know about this topic. In addition, what kind of networks do those interactions form? The Integrative Hypothesis of Specialization (IHS) may provide a cognitive map to generate predictions and interpret results. Specifically, resin heterogeneity, phylogeny, and geography may create interaction constraints that generate a modular or compound topology in resin foraging networks. Here we systematically reviewed resin foraging interactions with a multilayer network approach accounting for biogeographical structure. A total of 1,037 bee–plant resin foraging interactions were retrieved and Anacardiaceae and Dipterocarpaceae were identified as the most frequently visited plant families worldwide. As deduced from the IHS, we found a modular topology in most cases. A compound topology was only found with a less conservative approach considering all data. In most cases, Mantel tests revealed that interactions, modules, and layers are constrained by phylogeny and geography. Our results suggest that closely related species tend to interact with similar plant genera and from the same biogeographical region. Body size was positively correlated with centrality, indicating that larger bees use highly connected plants. We hope our findings highlight the ecological patterns and drivers that shape resin foraging interactions in stingless bees. Moreover, we discuss methodological recommendations and knowledge gaps, helping to guide future studies.