Biology subjects

Bridges, A.

Publications and source records attributed to Bridges, A..

3 recordsLinked to original sources

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↗