COS 73-2 - CANCELLED - Ordering and topological defects in social wasps’ nests

Abstract: Social insects have evolved a variety of architectural formations. Bees and wasps are well known for their ability to achieve compact structures by building hexagonal cells. How do multiple individuals in a group or a colony come together to construct these tiled layouts? The principle of stigmergy explains this as the formation of patterns by emergence, including self-organisation and self-assembly mechanisms. In most species, the construction rules depend on environmental (e.g., humidity, soil moisture) or pheromone gradients. In this context, the relative importance of self-organised vs template-based interactions has been examined, and current evidence points towards architectural mechanisms being an interactive effect of both these interactions. Polistes wattii, an open nesting paper wasp species, builds planar hexagonal structures. Paper wasps of Polistes genus build nests hanging from one or more stalks. The nest itself is made up of open hexagonal cells. Variations in nesting architectures within paper wasps have been attributed to selection pressures such as predation from ants or flying insects, insulation from heat, and economic use of building material. Here, using the pair correlation function approach, we show that their nests exhibit short-range hexagonal order (no long-range order) akin to amorphous materials. Hexagonal orientational order was well preserved globally. We also show the presence of topological defects such as dislocations (pentagon-heptagon disclination pairs) and Stone- Wales quadrupoles, and discuss how these defects were organised in the nest, thereby restoring order. Furthermore, we suggest the possible role of such defects in shaping nesting architectures of other social insect species.