Biology subjects

Woodgate, J. L.

Publications and source records attributed to Woodgate, J. L..

6 recordsLinked to original sources

bioRxiv2022

The establishment and transmission of novel foraging techniques indicates a capacity for culture in bumblebees (Bombus terrestris).

The astonishing behavioural repertoires of social insects have been thought largely innate, but these insects have repeatedly demonstrated remarkable capacities for both individual and social learning. Using the bumblebee Bombus terrestris as a model, we developed a two-option puzzle box task and used open diffusion paradigms to observe the transmission of novel, non-natural foraging behaviours through populations. Box-opening behaviour spread through colonies seeded with a demonstrator trained to perform one of the two possible behavioural variants, and the observers acquired the demonstrated variant. This preference persisted among observers even when the alternative technique was discovered. In control diffusion experiments that lacked a demonstrator, some bees spontaneously opened the puzzle boxes but were significantly less proficient than those that learned in the presence of a demonstrator. This suggested that social learning was crucial to proper acquisition of box-opening. Additional open diffusion experiments where two behavioural variants were initially present in similar proportions ended with a single variant becoming dominant, due to stochastic processes. This could lead to the emergence and maintenance of local cultural variation. These results suggest that bumblebees, like mammals and birds, may have the capacity for culture and to sustain cultural variation.

animal behavior and cognition↗

bioRxiv2022

Placement of new comb cells built by honeybees is guided by sub-cell scale features to align with the existing layout

The comb of honeybees has long been the subject of curiosity and admiration. Its noteworthy features include the even hexagonal layout and the sharing of walls, both side walls and bases, that provide a maximum storage volume while using a minimum of wax for its construction. The efficiency of its structure relies on a regular layout where cells are positioned correctly relative to each other. Each new cell should be placed exactly between two previously constructed cells, a task made more difficult by the incomplete nature of cells at the edge of comb where the new ones are to be built. By offering bees shaped wax stimuli we have identified sub-cell scale shapes that trigger certain patterns of behaviour by honeycomb construction workers. These behaviours, we found, cause the creation of a new cell to be aligned to small concavities and for cell walls to be built mid-way between two such stimuli. We show that by responding to the form of partially constructed comb, the bees build the next iteration of cells and walls at the locations necessary for the repeated pattern of cells to continue.

animal behavior and cognition↗

bioRxiv2022

Honeycomb cell walls are plastic; initially built as curves the walls are reformed by bees during subsequent construction

Honeybee comb comprises recognisable hexagons, each with straight sides. Not only are the cell side-walls flat, but so too are those that form the base of cells; base faces which are shared with cells on the opposite face of the comb. The mechanism by which bees build cells with flat sides has been the subject of speculation for centuries, but it has been conjectured by Kepler, Darwin as well as more recent researchers that bees build cylindrical cells that are transformed into flat sided prisms, without consensus as to the process by which this is achieved. By offering bees shaped wax stimuli and observing the comb that was built upon them, we have shown that under certain conditions walls will be curved and others where walls are reformed to be flat. A wall of a cell, be it a side-wall or a face of the base, with no other cell beyond it will be built as a convex curve whereas a wall with a cell to both sides will be formed flat. Furthermore, we show that these walls are plastic; walls that were initially built curved were re-shaped to be flat once a second adjacent cell had been built.

animal behavior and cognition↗

bioRxiv2022

Early-stage honeycomb contains non-uniform cells which are subsequently optimised

The hexagonal structure of honeycomb maximises storage volume while minimising the amount of wax required for its construction. How honeybee builders achieve this geometry, however, remains unclear. Previously, our group identified behavioural patterns that were triggered in builders when they encountered certain sub-scale features associated with partially constructed comb, which resulted in the alignment of new cells to small concavities and the construction of cell walls between two of these stimuli. This caused new cells to be built in the proper locations without the need for explicit instructions . Here, we investigated whether the hexagonal geometry of honeycomb cells resulted from the dense packing of cells that would otherwise have been circular tubes. We hypothesised that the reaction of a builder to a cell that is not fully enclosed by other cells would be an attempt to maximise the internal space by excavating and re-forming the surrounding walls to create a cylindrical interior. However, the creation of a cylindrical cell would be thwarted by the activities of workers within adjacent cells also acting according to these rules. Eventually an equilibrium will emerge with walls that meet at a junction arranged so that the available angular range (360{degrees}) is sub- divided equally between the cells that meet at the junction (typically, internal angles of 120{degrees} when three cells meet). To test this hypothesis, we offered wax stimuli to comb-building honeybees, shaped to encourage or to constrain the construction of comb cells, recording the bees progress. We found that at an early stage cells could be an irregular shape with curved walls and unequal wall lengths and corner angles, however, when allowed further time and unconstrained access the workers reshaped the cells achieving significantly greater regularity.

animal behavior and cognition↗

bioRxiv2022

Discrimination of edge orientation by bumblebees

Simple feature detectors in the visual system, such as edge-detectors, are likely to underlie even the most complex visual processing, so understanding the limits of these systems is crucial for a fuller understanding of visual processing. We investigated the ability of bumblebees (Bombus terrestris) to discriminate between differently angled edges. In a multiple-choice, "meadow-like" scenario, bumblebees successfully discriminated between angled bars with 7{degrees} differences, significantly exceeding the previously reported performance of eastern honeybees (Apis cerana, limit: 15{degrees}). Neither the number of choices required to learn, nor the bees final discrimination performance were affected by the angular orientation of the training bars, indicating a uniform performance across the visual field. Previous work has found that, in dual-choice tests, eastern honeybees cannot reliably discriminate between angles with less than 25{degrees} difference, suggesting that performance in discrimination tasks is affected by the training regime, and doesnt simply reflect the perceptual limitations of the visual system. We used high resolution LCD monitors to investigate the limits of bumblebees angular resolution in dual-choice experiments. Bumblebee could still discriminate 7{degrees} angle differences under such conditions (exceeding the previously reported limit for Apis mellifera, of 10{degrees}, as well as that of A. cerana), eventually reaching similar levels of accuracy, but required longer learning periods than under multiple-choice conditions. Bumblebees show impressive abilities to discriminate between angled edges, performing better than two previously tested species of honeybee. This high performance may, in turn, support complex visual processing in the bumblebee brain.

animal behavior and cognition↗

bioRxiv2020

Route following by one-eyed ants suggests a revised model of normal route following

The prevailing account of visually controlled routes is that an ant learns views as it follows a route, while guided by other path-setting mechanisms. Once a set of route views is memorised, the insect follows the route by turning and moving forwards when the view on the retina matches a stored view. We have engineered a situation in which this account cannot suffice in order to discover whether there may be additional components to the performance of routes. One-eyed wood ants were trained to navigate a short route in the laboratory guided by a single black, vertical bar placed in the blinded visual field. Ants thus had to turn away from the route to see the bar. They often turned to look at or beyond the bar and then turned to face in the direction of the goal. Tests in which the bar was shifted to be more peripheral or more frontal than in training produced a corresponding change in the ants paths, demonstrating that they were guided by the bar, presumably obtaining information during scanning turns towards the bar. Examination of the endpoints of turns away from the bar suggest that ants use the bar for guidance by learning how large a turn-back is needed to face the goal. We suggest that the ants zigzag paths are an integral part of visually guided route following. In addition, on some runs in which ants did not take a direct path to the goal, they still turned to face and sometimes approach the goal for a short stretch. This off-route goal facing indicates that they store a vector from start to goal and use path integration to track their position relative to the endpoint of the vector.

animal behavior and cognition↗