Learning, decision making and navigation in nocturnal bull ants

Insects possess small brains but exhibit sophisticated behaviour. Ants, in particular, are adept at navigating using cues in their environment, a task that requires complex cognitive processing. Environments, however, are often changing. In my thesis, I asked the question of how the ants learn and cope with the navigational challenges that arise when their environment changes. These studies provide greater insight into the reliance on different types of navigational cues and learning processes. To address this question, I focused on detour learning (Chapter-2), gap perception and learning (Chapter-3), coping with scene changes (Chapter-4) and the importance of different portions of views (Chapter-5) in the Australian nocturnal bull ant, Myrmecia midas, which forages on nearby eucalyptus trees and does not use pheromone trails. Through these studies I have demonstrated that ants do not alter their natural foraging path initially when it is disrupted by visual obstacles; however, their navigation was profoundly affected when they encountered any new olfactory or tactile cues. In both natural and experimental set-ups, alterations to the visual panorama significantly disrupted the ants’ ability to forage. Nevertheless, over a few trips, success at negotiating obstacles, finding a gap or coping with disrupted panoramas increased, visual scans were reduced, the paths became straighter, and individuals took less time to reach the goal. Overall, my findings suggest that these ants learn quickly to cope with navigational challenges and show flexibility in navigation. In addition, I used the natural habitat to test the learning and cognitive ability of ants instead of laboratory conditions, opening up new opportunities for future research in the cognitive ecology of learning. This small-brained insect makes a promising model for unravelling further mechanisms of cognition and perhaps aid in the design of robotic navigational systems.