Vibrating donor-partners during trophallaxis modulate associative learning ability of food receivers in the stingless bee Melipona quadrifasciata

Multiple sensory modalities within a communication context lead to an increased responsiveness of the receptor. Due to this increase in attention when exposed to multiple stimuli, it is possible that the learning ability of a receiver is modulated through communication signals. Stingless bees (Apidae; Meliponini) are a good model to use in order to investigate communication systems because they display a much wider behavioural repertoire regarding foraging and communication than the thoroughly studied honeybee Apis mellifera. Similar to honeybees, meliponine bees show appetitive unconditioned responses (extension of the proboscis after contacting sugar with the antennae) that may be conditioned to odour. Such associative learning events take place within the nest, for instance, when a successful forager unloads the nectar collected in the field to receiver partners (trophallaxis). During these contacts, receivers obtain multimodal information about the collected resource, such as its sugar content, its specific scent, and, in case of several meliponine species such as Melipona quadrifasciata, thoracic pulsed vibrations produced by the food donors. These vibrations correlate with the profitability of the resource exploited by the forager. With this in mind, we asked whether and to what extent food receivers in stingless bee colonies (M. quadrifasciata) integrate this multimodal information – vibratory–olfactory–gustatory – while receiving food from foragers. We found that the scented food elicited stronger vibrations (longer and more frequent vibrations with an overall higher duty cycle) than unscented food of equal sugar content. We also observed a positive correlation between the amount of vibrations a bee received during trophallaxis and its subsequent learning performance in a proboscis extension response conditioning procedure. Our findings suggest that the vibrations during trophallaxis affect the receiver's behaviour by modulating its ability to establish the food-odour association.