Phantom alternatives influence food preferences in the eastern honey bee Apis cerana

1. Most models of animal choice behaviour assume that desirable but unavailable options, such as a high quality, but inhabited nest site, do not influence an individual’s preferences for the remaining options. However, experiments suggest that in mammals such ‘phantom’ alternatives can alter, and even reverse, an individual’s preferences for other items in a choice set. 2. Here we investigate the effect of phantom alternatives on feeder preferences in the eastern honey bee, Apis cerana. 3. First, we tested the effects of unattractive and attractive phantom by presenting individual bees with either a binary choice set containing two feeders that differed strongly in two qualities, but were equally preferred overall (‘the target’ and ‘the competitor’), or a trinary choice set containing the target, the competitor and one of two phantom types (unattractive and attractive). Second, we determined whether phantoms change preferences between the competitor and target by increasing preference towards or away from the phantom-similar available choice. 4. Attractive phantoms consistently changed individual bee preferences in favour of the phantom-similar choice. 5. Our study shows that the phantom alternative effect is not limited to mammals. Moreover, the phantom effect can shift individual preference in a consistent and predictable way. Our results highlight the importance of considering the potential for phantom effects when considering the foraging behaviour of animals in natural environments.