Habitats shape the cuticular chemical profiles of stingless bees

Stingless bees are highly social pollinators in tropical ecosystems. Besides floral pollen and nectar, they collect substantial amounts of plant resins, which are used for nest construction/maintenance and defence against antagonists. Moreover, some stingless bees extract chemical compounds from resins and incorporate them in their cuticular chemical profiles, rendering this trait directly dependent on the plant community of the surrounding environment. While previous studies have investigated how variation in the composition and diversity of available resin sources affect resin storages inside hives, subsequent effects on the bees' cuticular chemistry have not been studied. To fill this gap, we investigated the number, proportion and composition of compounds in the cuticular chemical profile of an Australian stingless bee using gas chromatography and mass spectrometry. We analysed whether and (if so) how the cuticular chemistry was affected by habitat (i.e., plantations, forests, and gardens) and tree species richness. We found that overall numbers and proportions of self-produced and resin-derived compounds in the cuticular chemical profiles of Tetragonula carbonaria were similar across habitats, while the composition of all compounds (i.e., both self-produced and resin-derived) and of resin-derived compounds differed between habitats. This indicates that the surrounding tree species community and thus available resin chemistry affected the composition of particularly resin-derived compounds on the bees' cuticle. As the number and composition of resin-derived cuticular compounds were not affected by tree species richness, stingless bees appear to selectively incorporate specific compounds available in the surrounding environment in their cuticular chemical profiles, which may increase their defensive properties.