Interactions between plants and ants abound in nature and
have significant consequences for ecosystem functioning. Recently, it has been
suggested that nectar-foraging ants transport microorganisms to flowers; more
specifically, they transport yeasts, which can potentially consume sugars and
alter nectar composition. Therefore, ants could indirectly change nectar sugar
profile, an important floral feature involved in the plant–pollinator
mutualism. But this novel role for ants has never been tested. We here
investigate the effects of nectarivorous ants and their associated yeasts on
the floral nectar sugar composition of an ant-pollinated plant.