Stigmergy versus behavioral flexibility and planning in honeybee comb construction

TLDR: Chittka et al. as mentioned in this paper show that bees also build various types of irregularly shaped and sized cells, for example when merging separate comb constructions, which raises the question of whether the bees' innate behavioral repertoire contains multiple different routines for each shape, whether bees plan ahead to insert optimal shapes, or whether such diversity of structures could be explained by simple rules.

Abstract: Perhaps the most magnificent animal building structure is the honeybee wax comb—a double-sided sheet of tessellated, near-horizontal hexagonal cells. The cells are built either side of a common backplane that forms a base for those to either side. This typically highly regular structure has been shown to be mathematically optimal to maximize storage space and stability while minimizing building material (1). However, Smith et al. (2) show that bees also build various types of irregularly shaped and sized cells, for example when merging separate comb constructions. This raises the question of whether the bees’ innate behavioral repertoire contains multiple different routines for each shape, whether bees plan ahead to insert optimal shapes, or whether such diversity of structures could be explained by simple rules. The hexagonal grid structure of honeycomb, constructed by a leaderless collective of hundreds of bees, lends itself to speculation that a robotic, repetitive innate behavior routine must be at work. An analogy is the construction of a brick wall, where each new layer is built by adding new bricks in a staggered, one-over-two pattern. This can be efficiently achieved by a robot without the architect’s supervision (3). This concept—where the features of an existing structure are used to add the next element of the structure by a simple rule—is called stigmergy (4, 5). The perceived analogy between insect cells and bricks has led some social insect researchers to model comb construction as the simple process of fitting new, complete comb cells onto the existing structure (5). However, a hexagonal cell is not an externally supplied prefabricated unit. Rather, the bee builds a cell using small specks of wax which are chewed, deposited, and sculpted into the walls (6) to form a hexagon of equal-length sides with internal angles of 120°. And this is not … [↵][1]1To whom correspondence may be addressed. Email: l.chittka{at}qmul.ac.uk. [1]: #xref-corresp-1-1