Substrate evaporation drives collective construction in termites
- Life Sciences Department, University of Roehampton, United Kingdom
- Service de Chimie et Physique Non Linéaire, Université Libre de Bruxelles, Belgium
- Laboratoire Matière et Systèmes Complexe, CNRS, Université Paris Cité, France
- Laboratoire d’Ethologie Expérimentale et Comparée, LEEC, UR 4443, Université Sorbonne Paris Nord, France
- Networks Unit, IMT School for Advanced Studies Lucca, Italy
Figures
Figure 1 with 2 supplements
Experimental setup.
Sketch of the experimental setup (left) and snapshot of one experiment (E66) before termites were added to the setup (right). The white marks on the picture give the scale of the setup, with the distance between successive marks being 1, 3, and 5 cm.
Figure 1—figure supplement 1
Close-up on pillar structures built by our captive colony of Coptotermes gestroi within the plastic barrel that hosts the full colony.
Figure 1—figure supplement 2
Temperature (blue) and humidity (red) within the Petri dish as a function of time.
The shaded area refers to a time interval where the probe was placed on the bottom plate of the Petri dish but outside the clay disk. During the remaining time, the probe was placed on the clay disk.
Figure 2
Experimental results - heatmaps.
Top: (A) cumulative heatmaps of deposition (; blue) and collection activity (; yellow) normalized by their respective mean values for one experiment (E66), colorbars are the same as in panel (E); (B) cumulative depositions (top) and collections (bottom) per unit area as a function of the Petri dish radius for experiments E58, E63, E65, E66, and E76, all histograms have been normalized and sum up to 1; (C) comparison among experimental depositions (in red), surface curvature (in blue) shown in Figure 3C, and depositions predicted by simulations (black) shown in Figure 3C, all the quantities are computed along the radial cut shown in panel (A), depositions are normalized by their maximum value and curvature is in ; (D) cumulative occupancy heatmap normalized by its mean value for E66; (E) depositions (; blue) and collections (; yellow) conditional to cumulative normalized occupancy for E66.
Figure 3 with 3 supplements
Laboratory experiments and simulations of the growth model.
Top row: snapshots of a building experiment with ‘pillars’ cue (E66) (A) and a building experiment with ‘wall’ cue (E78) (B). Bottom row: snapshots of 3D simulations initiated with copies of the experimental setup E66 (C, D) and E78 (E, F) in which nest growth is entirely determined by the local surface curvature (based on our previously described model Facchini et al., 2020). Snapshots C and E refer to t=0, D and F refer to t=9 (dimensionless). The color map corresponds to the value of the mean curvature at the interface air-nest. White indicates convex regions and black indicates concave regions. The scale bars correspond to 1 cm.
Figure 3—figure supplement 1
Snapshots of experiments with pillar cues.
Superimposed labels denote: the experiment ID (top left), the time after the start of the experiment at which the picture was taken (top right) and the ID of the master colony (bottom right).
Figure 3—figure supplement 2
Snapshots of experiments with wall cues.
Superimposed labels denote: the experiment ID (top left), the time after the start of the experiment at which the picture was taken (top right) and the ID of the master colony (bottom right).
Figure 3—figure supplement 3
Snapshots of experiments with no cues.
Superimposed labels denote: the experiment ID (top left), the time after the start of the experiment at which the picture was taken (top right) and the ID of the master colony (bottom right).
Figure 4
Diffusive simulations and chemical garden experiments.
Top row: contour of the humidity gradient obtained solving the Laplace equation in a cubic domain with a humid bottom boundary (in brown) which is mapped from 3D scans of the experimental setup in E66 (A) and E78 (B). At the top boundary is fixed to which was the average value of humidity in our experimental room. Note that is the relative humidity, thus the magnitude of the humidity gradient is measured in , i.e means a humidity variation of 10% over . Each contour corresponds to a variation of . Pillar tips are associated with a strong humidity gradient; the top of the wall is also associated with a strong humidity gradient, although not as strong as at the pillar tips. Also note that humidity gradient at the top corners of the wall is 30% stronger than on the rest of the top edge. Bottom row: snapshots of chemical garden experiments initiated with ‘pillars’ cue (C), and with ‘wall’ cue (D). All the scale bars correspond to .
Appendix 1—figure 1
Sketch of curvature definition on a saddle shaped surface.
Appendix 2—figure 1
Sketch of the experimental setup showing the contrast between how sharp is the shape of the wet substrate (orange region) at the disk edge, and how flat the same region can appear to a walking termite.
Tables
Table 1
Summary table of experiments.
Color labels in the leftmost column denote batteries of identical simultaneous experiments. Orange highlighting denotes wall experiments where deposits focused at the lateral tips of the top wall edge. Experiment IDs labeled with a * refer to cases where: the clay disk dried prematurely (57,74,75); hydrating holes were drilled on one half of the disk (76); a larger number of workers (n=150) was introduced in the arena.
| Exp ID | Cue type | Cues deposits (any time) | Edge eposits | Else where deposits | Spontaneous holes |
|---|---|---|---|---|---|
| 48 | Pillars | Yes | No | Minor | 1 |
| 52 | Pillars | Yes | No | No | No |
| 53 | Pillars | Yes | Yes | Some | No |
| 57* | Pillars | Minor | No | Some | Yes |
| 58 | Pillars | Yes | Yes | Minor | No |
| 59 | Pillars | Some | No | minor | Yes |
| 63 | Pillars | Yes | Yes | No | No |
| 64 | Pillars | Yes | Yes | No | 1 |
| 65 | Pillars | Yes | Yes | No | 1 |
| 66 | Pillars | Yes | Yes | No | No |
| 67 | Pillars | Yes | Yes | Yes | Yes |
| 72 | Pillars | Yes | Yes | No | No |
| 73 | Pillars | Yes | Yes | Some | Yes |
| 74* | Pillars | Yes | Yes | Yes | Yes |
| 75* | Pillars | Yes | No | Yes | Yes |
| 76* | Pillars | Yes | No | No | No |
| 49* | Wall | Yes | No | No | n/a |
| 71 | Wall | Some | Yes | Minor | No |
| 77 | Wall | Yes | Yes | Some | Yes |
| 78 | Wall | Yes | Yes | No | No |
| 79 | Wall | Yes | Yes | Minor | No |
| 81 | Wall | Yes | Yes | Some | Yes |
| 90 | Wall | No | No | Yes | Yes |
| 91 | Wall | Yes | Yes | No | No |
| 92 | Wall | Yes | Yes | Minor | Yes |
| 93 | Wall | Yes | Yes | No | 1? |
| 94 | Wall | Yes | Yes | Minor | Yes |
| 83 | None | Spont. pillars | Yes | Minor | Non |
| 84 | None | n/a | Yes | Minor | Yes |
| 85 | None | n/A | Yes | No | No |
| 86 | None | Spont. pillars | Yes | No | No |
| 87 | None | n/A | Yes | Some | Yes |
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Substrate evaporation drives collective construction in termites
eLife 12:RP86843.
https://doi.org/10.7554/eLife.86843.4
