5.3. Tactile conditioning
Similar to olfactory conditioning, bees can be trained to associate a tactile stimulus with proboscis extension (Fig. 5C, D). In this paradigm, the bee learns to associate the characteristics of a tactile stimulus with a sucrose reward. In contrast to olfactory conditioning, the eyes of the bee have to be occluded by black paint before training it to tactile cues. This improves tactile scanning behaviour. The tactile cue, which can be a small plate (3 x 4 mm, Scheiner et al., 1999), is first presented to the bee for analysis of spontaneous behaviour like for olfactory conditioning (Fig. 5C). As soon as the plate is brought into the scanning range of the bee antennae, the animal starts scanning the tactile stimulus with its antennae. This behaviour is normally not associated with proboscis extension. During training, the plate is repeatedly brought into the scanning range of the bee’s antennae and while the bee touches the plate, proboscis extension is elicited by also applying a small droplet of sucrose solution to its antennae (see olfactory conditioning, sections 5.1. and 4.2.) and the bee is allowed to drink from the sucrose solution. While the bee is licking the sucrose, the plate is removed from the scanning range. Like in classical olfactory conditioning, bees learn to show proboscis extension to tactile stimuli after one or two trainings (Erber et al., 1998; Scheiner et al., 1999, 2001a, b) and retain long-lasting tactile memories (Scheiner et al., 2001a).