Olfactory Information Transfer in Bumblebees and Its Variation According to the Food Resource.

Within the framework of animal learning theory, information transfer refers to the generalization or transmission of acquired knowledge to novel situations, individuals, or environments. In pollinators, this process is critical for adaptive foraging and ecological success. Although olfactory information transfer has been demonstrated in bumblebees through classical conditioning or colony exposure, the influence of reward type (nectar vs. pollen) remains poorly understood. Here, we evaluated olfactory information transfer and decision-making in the South American bumblebee Bombus pauloensis using complementary laboratory and colony-based experiments. Under laboratory conditions, bees were either classically conditioned through the proboscis extension reflex (PER) paradigm using scented sucrose solution or exposed overnight to scented pollen and subsequently tested in a four-arm arena. In a more natural context, colonies were exposed to scented sucrose solution or scented pollen through in-nest feeders, after which foraging choices were assessed in a flight cage. Sucrose-conditioned bees exhibited an odor-contingent preference in the four-arm arena, consistent with associative learning under our conditions. In contrast, pollen exposure produced odor-associated trends. Linalool exhibited a bias, although airborne volatile concentrations were not directly quantified, representing a methodological limitation. Moreover, linalool-scented pollen induced intense feeder manipulation and increased mortality during overnight exposure, highlighting substantial physiological costs. Under colony conditions, 24-h exposure to scented pollen promoted significant odor-guided search preferences, particularly with linalool, whereas no significant effect of scented sucrose was detected under our 24 h in-nest exposure; individual feeder contact was not verified. Overall, behavioral responses varied jointly with odor identity and the combined operational framework; the salience of pollen-associated odors observed here is consistent with reward-specific effects but cannot be fully disentangled from differences in protocol structure between the sucrose and pollen experiments.