Olfactory associative learning in the Australian stingless bee Tetragonula carbonaria

Abstract

Flower-visiting social insects use a variety of cues to help them learn and recall which flowers are high-quality resources, including the flower odour. In addition, some species may learn to respond to the odours left at flowers by other insects, either to avoid flowers that have likely been depleted by recent visitors, or to identify profitable floral patches being used by competitors. For example, Australian stingless bees were observed to be more attracted to food sources recently visited, and thus odour-marked, by other stingless bees or honey bees than food sources with no prior visits. Here, we use a proboscis extension response (PER) protocol to investigate the capacity for olfactory associative learning in the Australian stingless bee, Tetragonula carbonaria. We test the ability of T. carbonaria to learn to associate a food reward with each odour in two paired sets of odours: (1) vanilla vs. lavender, and (2) linalool vs. a synthetic version of the honey bee pheromone Nasonov. After conditioning, T. carbonaria foragers demonstrated successful discrimination between the two different odours in a set, learnt to associate all four test odours with a food reward, and maintained this association for 15 min after training. In all, our results, therefore, show that PER can be used to investigate associative learning in T. carbonaria and support olfactory associative learning as a mechanism by which the odours of both flowers and other bees affect foraging decisions in this species.