Chemical and microbial ecology of the bee brood cell: insights from the hoary squash bee, Peponapis pruinosa (Eucerini, Apidae)

There is mounting evidence for declines in both managed and wild pollinator species, necessitating support for wild bee populations in order to maintain pollination services. Solitary, ground-nesting bees, which comprise the vast majority of bees in the world, store a mixture of pollen and nectar in brood cells excavated from the soil. The semi-liquid, pollen-nectar provision mass is rich in carbohydrates (primarily from nectar), proteins (primarily from pollen), and a variety of plant secondary compounds. The provision mass can also be host to a diverse microbial fauna, although their role in this mini-ecosystem is largely unknown. Currently, we also know little about the impact of pollen quality and pesticides on the microbial fauna of the bee cell and how these effects might impact bee larval development. We are investigating these questions in an abundant, widespread, and economically important ground-nesting solitary bee, the hoary squash bee, Peponapis pruinosa (Apidae).