The bacterial community throughout the life cycle and in the food of the Australian solitary bee, Megachile tosticauda

The bacterial associations in the food and throughout metamorphosis of the Australian, solitary, resin bee Megachile tosticauda are characterised. The bacterial community associated with M. tosticauda exhibited stability across two years of sampling, and adults, larvae and prepupae harboured distinct communities. We experimentally demonstrate that the adult microbiota are environmentally acquired and depend on the substrates encountered by the adults. Free-flying adult bees shared similar bacterial communities to pollen provisions, with Acinetobacter, a common nectar-associated taxon, dominating these samples. In larval provisions, the relative abundance of Acinetobacter decreases over time and was mostly absent in older brood, suggesting its potential consumption as food or a transient nature. Tyzzerella was prevalent in feeding larvae and prepupae, yet absent in adults. Antibiotic treatment of larval food supplies to remove live bacteria did not change brood developmental or survival, suggesting live bacteria may not be essential for larval growth. The combined observations indicate the gut microbiome is environmentally acquired, and that this species does not possess a heritable, functional gut microbiome.