Using pupae as appetitive reinforcement to study visual and tactile associative learning in the Ponerine ant Diacamma indicum

Associative learning is of great importance to animals, as it enhances their ability to navigate, forage, evade predation and improve fitness. Even though associative learning abilities of Hymenopterans have been explored, many of these studies offered food as appetitive reinforcement. In the current study, we focus on tactile and visual cue learning in an ant Diacamma indicum using a Y-maze setup with pupa as a positive reinforcement. Using pupa as a reward resulted in a significantly higher proportion of ants completing the training in a shorter time as compared to using food as reinforcement. Ants spent significantly more time in the conditioned arm for both visual cues (white dots or black dots) and tactile cues (rough or smooth surfaces) presented on the floor when associated with pupa, thus showing that they were capable of associative learning. On encountering a conflict between visual and tactile cues during the test, ants chose to spend significantly more time on the arm with the tactile cues indicating that they had made a stronger association between pupa and the tactile cue as compared to the visual cue during training. Using pupa as an ecologically relevant reward, we show that these solitary foraging ants living in small colonies are capable of visual and tactile associative learning and are likely to learn tactile cues over visual cues in association with pupa.