Rathery, A. | Search bioRxiv

bioRxiv2025

High environmental temperatures put nest excavation by ants on fast forward: they dig the same nests, faster.

Environmental temperature influences the physiology and the behaviour of ectothermic organisms, including ants. However, the complex collective behaviour exhibited by ant colonies means that it is difficult to predict how the effects of temperature translate to colony-level functioning and features, such as the form of their nests. This study aims to determine the effects of environmental temperature on nest excavation rate and on the morphology of excavated nests. To this end, we characterized the nest digging activity of the yellow meadow ant Lasius flavus confined to dig in a nearly two-dimensional experimental setup maintained at a constant temperature ranging from 15 to 30 degrees Celsius. Ants dug faster at higher temperature, with an increase of digging rate that reflected the temperature-induced increase of movement speed of individual ants. Nevertheless, the shape of excavated nests remained statistically unchanged across the full range of temperatures we tested. These results suggest that temperature accelerates all aspects of the excavation process uniformly, rather than selectively influencing specific components such as tunnel branching or elongation. The ability to produce a consistent overall nest structure, irrespective of the temperature conditions encountered at the time of digging, may provide adaptive benefits to the colony.

animal behavior and cognition↗

bioRxiv2023

Substrate evaporation drives collective construction in termites

Termites build complex nests which are an impressive example of self-organization. We know that the coordinated actions involved in the construction of these nests by multiple individuals are primarily mediated by signals and cues embedded in the structure of the nest itself. However, to date there is still no scientific consensus about the nature of the stimuli that guide termite construction, and how they are sensed by termites. In order to address these questions, we studied the early building behavior of Coptotermes gestroi termites in artificial arenas, decorated with topographic cues to stimulate construction. Pellet collections were evenly distributed across the experimental setup, compatible with a collection mechanism that is not affected by local topography, but only by the distribution of termite occupancy (termites pick pellets at the positions where they are). Conversely, pellet depositions were concentrated at locations of high surface curvature and at the boundaries between different types of substrate. The single feature shared by all pellet deposition regions was that they correspond to local maxima in the evaporation flux. We can show analytically and we confirm experimentally that evaporation flux is directly proportional to the local curvature of nest surfaces. Taken together, our results indicate that surface curvature is sufficient to organize termite building activity, and that termites likely sense curvature indirectly through substrate evaporation. Our findings reconcile the apparently discordant results of previous studies.

biophysics↗