Biology subjects

deeti, s.

Publications and source records attributed to deeti, s..

6 recordsLinked to original sources

bioRxiv2025

Ants oscillate and scan more in navigation when the visual scene changes

Solitarily foraging ants learn to navigate between important locations by comparing their current view with memorized scenes along a familiar route. As desert ants, in particular, travel between their nest and a food source, they establish stable and visually guided routes that guide them without relying on trail pheromones. We investigated how changes in familiar visual scenes affect the navigation of the red honey ant (Melophorus bagoti). In Experiment 1, ants were trained to follow a one-way diamond-shaped path to forage and return home. We manipulated scene familiarity by adding a board on their homebound route just before the nest. In Experiment 2, ants were trained to travel a straight path from their nest to a feeder, and we removed the prominent landmarks on the route after they had established a stable route. We predicted that these scene changes would cause the ants to deviate from their usual straight paths, slow down, scan more, and increase their lateral oscillations to gather additional information. Our findings showed that when the familiar scene was changed, ants oscillated more, slowed their speed, and increased scanning bouts, indicating a shift from exploiting known information to more actively exploring and learning new visual cues. These results suggest that scene familiarity plays a crucial role in ant navigation, and changes in their visual environment lead to distinct behavioral adaptations aimed at learning about the new cues.

ecology↗

bioRxiv2024

Intricacies of running a route without success in night-active bull ants (Myrmecia midas)

How do ants resolve conflicts between different sets of navigational cues during navigation? When two cue sets point to diametrically opposite directions, theories predict that animals should pick one set of cues or the other. Here we tested how nocturnal bull ants Myrmecia midas adjust their paths along established routes if route following does not lead to their entry into their nest. During testing, foragers were repeatedly placed back along their homeward route up to nine times, a procedure called rewinding. This procedure produced an accumulating path integrator, or vector, in diametric opposition to the learned landmark views of the route. Repeated rewinding made some individuals head initially in the nest-to-feeder vector direction, but all ants ended up using the visual scene for homing, demonstrating the importance of view-based homing in this species. Repeated rewinding, however, led to path deteriorations, with increased path meander and scanning, results also found in desert ants. After nine rewinding trips, ants were displaced off their route in further manipulations, to a site near the nest, an unfamiliar site, or with the terrestrial surround entirely covered. The results show that a change in visual conditions diminished the weight accorded to path integration: the off-route ants no longer headed off in the vector direction as they did on the immediately preceding trial. They relied on celestial compass cues in other ways for homing. Experiment 2 showed the effects of rewinding in the unaltered natural habitat were not view-specific in these bull ants.

ecology↗

bioRxiv2024

A Method for Visual Psychophysics based on the Navigational Behaviour of Desert Ants (Melophorus bagoti)

The Australian desert ant Melophorus bagoti is known to navigate in their complex visual environment relying on path integration and landmark learning. We investigated the navigational behaviour of desert ants in response to visual stimulus changes along their route to a food source. Ants were trained to self-navigate a track between their nest and a feeder, with visual stimuli introduced near the feeder. After three days of training, we altered the visual scene by changing colours and observed the ants reactions. The results showed that ants in the test conditions, when visual changes were introduced, displayed more meandering paths, increased scanning behaviour, and slower speeds compared to control conditions. The sinuosity of their paths increased, and their orientation became less efficient. Additionally, changes in colour led to significant alterations in path characteristics, including a higher frequency of head oscillations and deviations from straight-line paths. These findings suggest that disruption to visual cues used for navigation causes noticeable changes in their movement patterns. A subset of these changes, easy to measure and calculate, can provide a signature to indicate that ants have detected a change in the visual stimuli. This proof-of-concept study thus highlights a method for studying visual psychophysics in ants in their natural habitat.

animal behavior and cognition↗

bioRxiv2024

Desert ant (Melophorus bagoti) dumpers learn from experience to improve waste disposal and show spatial fidelity

The Central Australian red honey-pot ant Melophorus bagoti maintains non-cryptic ground-nesting colonies in the semi-desert habitat, performing all the activities outside the nest during the hottest periods of summer days. These ants rely on path integration and view-based cues for navigation. They manage waste by taking out unwanted food, dead nestmates, and some other wastes, typically depositing such items at distances > 5 m from the nest entrance, a process called dumping. We found that over multiple runs, dumpers headed in the same general direction, showing sector fidelity. Experienced ants dumped waste more efficiently than naive ants. Naive individuals, lacking prior exposure to the outdoor environment around the nest, exhibited much scanning and meandering during waste disposal. In contrast, experienced ants dumped waste with straighter paths and a notable absence of scanning behaviour. Furthermore, experienced dumpers deposited waste at a greater distance from the nest compared to their naive counterparts. We also investigated the navigational knowledge of naive and experienced dumpers by displacing them 2 metres away from the nest. Naive dumpers were not oriented towards the nest in their initial trajectory at any of the 2m test locations, whereas experienced dumpers were oriented towards the nest at all test locations. Naive dumpers were nest-oriented as a group, however, at the test location nearest to where they dumped their waste. These differences suggest that in red honey ants, learning supports waste disposal, with dumping being refined through experience. Dumpers gain greater spatial knowledge through repeated runs outside the nest, contributing to successful homing behaviour. Simple SummaryEusocial insects maintain hygiene in their nests with cleaning behaviours. One such behaviour is the disposal of refuse material, food waste, dead nestmate bodies, and other waste, outside the nest. This study on the waste disposal behaviour of Central Australian red honey-pot ants, Melophorus bagoti, provides valuable insights into the significance of learning in waste disposal. Naive ants improved over five consecutive runs in waste dumping, running straighter paths with less scanning. The observed differences between experienced and naive ants in waste dumping imply that learning contributes to more streamlined and less time-consuming waste management. In addition, dumping ants established sector fidelity in the consecutive runs, heading mostly in the same general direction on each dumping trip. This behaviour reduces the amount of navigational expertise that the dumper has to acquire. Learning in individuals thus helps an ant colony to cope with not only navigational challenges in foraging, which have been well studied in this and other desert ant species, but also with other demands of living in a harsh desert habitat.

animal behavior and cognition↗

bioRxiv2024

Experience improves navigational knowledge of dumpers in desert ants (Melophorus bagoti)

The Australian red honey ant, Melophorus bagoti, is an excellent desert navigator, performing all the activities outside the nest during the hottest periods of summer days. This species relies heavily on path integration and landmark cues for outbound and inbound navigation. Although the species navigational behaviours have been much studied, the spatial knowledge of workers that dump waste has not been investigated. In our study, we investigated the navigational knowledge of both naive and experienced dumpers by displacing them 2 metres away from the nest. Naive dumpers were not oriented towards the nest in their initial trajectory at any of the test locations, whereas experienced dumpers were significantly oriented towards the nest at all test locations. Naive dumpers were nest-oriented as a group, however, at the test location nearest to where they dumped their waste. Compared with experienced dumpers, the paths of naive dumpers were more sinuous, and naive dumpers scanned more on tests. Overall, our findings suggest that dumpers gain greater spatial knowledge through repeated dumping runs outside the nest, contributing to successful homing behaviour.

animal behavior and cognition↗

bioRxiv2024

Neophobic response of bull ants (Myrmecia midas) to odours introduced on their foraging route

Goal-oriented learning and navigation is well known in eusocial insects. The solitary foraging of nocturnal bull ants Myrmecia midas in their visually complex environment relies on path integration and landmark learning. While this species seems to be sensitive to handling and reacts to visual changes in their surroundings, not much is known about how added olfactory stimuli impact their route navigation on a vertical surface. In the current study, we added one of five different invisible odours on the trees on which foragers normally forage. We found that the bull ants showed neophobic responses to all the odours. The Tea-tree and Lavender odours showed the strongest impact on the bull ants navigation by causing detours, U-turns, and avoidance of the sensory stimuli, with the ants meandering more and scanning more frequently. The odours of Olive oil, Flax-seed oil, and Eucalyptus oil had a moderate impact on the ants navigation. These findings showed the widespread influence of non-visual chemical cues in shaping bull ant navigation and highlight the induction of neophobic responses stemming from chemical alterations on learned routes. Overall, this study contributes to the understanding of the effects of foreign odours, adding to our understanding of the complex learning processes of bull ants in their vertical navigation.

animal behavior and cognition↗