# Surface curvature guides early construction activity in mound-building termites

## TL;DR

This study demonstrates that surface curvature influences early construction activity in mound-building termites, suggesting topographical cues play a key role in colony coordination beyond chemical signals.

## Contribution

It provides experimental evidence that surface curvature, rather than inclination or height, guides termite soil displacement and exploration activities, highlighting the importance of topographical cues.

## Key findings

- Soil displacement correlates with surface curvature.
- Early exploration activity is influenced by surface curvature.
- Topographical cues serve as a physical memory for termite activity.

## Abstract

Termite colonies construct towering, complex mounds, in a classic example of distributed agents coordinating their activity via interaction with a shared environment. The traditional explanation for how this coordination occurs focuses on the idea of a "cement pheromone", a chemical signal left with deposited soil that triggers further deposition. Recent research has called this idea into question, pointing to a more complicated behavioral response to cues perceived with multiple senses. In this work, we explored the role of topological cues in affecting early construction activity in Macrotermes. We created artificial surfaces with a known range of curvatures, coated them with nest soil, placed groups of major workers on them, and evaluated soil displacement as a function of location at the end of one hour. Each point on the surface has a given curvature, inclination, and absolute height; to disambiguate these factors, we conducted experiments with the surface in different orientations. Soil displacement activity is consistently correlated with surface curvature, and not with inclination nor height. Early exploration activity is also correlated with curvature, to a lesser degree. Topographical cues provide a long-term physical memory of building activity in a manner that ephemeral pheromone labeling cannot. Elucidating the roles of these and other cues for group coordination may help provide organizing principles for swarm robotics and other artificial systems.