Floral visitors and ant scent marks: noticed but not used?

1. Bee behaviour when visiting flowers is mediated by diverse chemical cues and signals, from the flower itself and from previous visitors to the flower. Flowers recently visited by bees and hoverflies may be rejected for a period of time by subsequent bee visitors.2. Nectar-thieving ants also commonly visit flowers and could potentially influence the foraging decisions of bees, through the detection of ant trail pheromones or footprint hydrocarbons.3. Here we demonstrate that, while naïve bumblebees in laboratory trials are not inherently repelled by ant scent marks, they can learn to use them as informative signals while foraging on artificial flowers.4. To test for similar activity in the wild, visitor behaviours at the flowers of Digitalis purpurea Linnaeus, Bupleurum fruticosum Linnaeus, and Brassica juncea (Linnaeus) Czernajew were compared between flowers that had been in contact with ants and those that had not. No differences were found between the two treatments.5. The use of chemical foraging cues by bees would appear to be strongly dependent on previous experience and in the context of these plant species bees did not associate ant scent mark cues with foraging costs