Figures and data in Substrate evaporation drives collective construction in termites

Figures
Tables
Additional files

6 figures, 1 table and 1 additional file

Figures

Figure 1 with 2 supplements

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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

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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

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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

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Experimental results - heatmaps.

Top: (A) cumulative heatmaps of deposition ( $P (D)$ ; blue) and collection activity ( $P (C)$ ; 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 ${mm}^{- 1}$ ; (D) cumulative occupancy heatmap normalized by its mean value for E66; (E) depositions ( $P (D | O)$ ; blue) and collections ( $P (C | O)$ ; yellow) conditional to cumulative normalized occupancy for E66.

Figure 3 with 3 supplements

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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

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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

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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

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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

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Diffusive simulations and chemical garden experiments.

Top row: contour of the humidity gradient $\nabla h$ obtained solving the Laplace equation $Δ h = 0$ in a cubic domain with a humid bottom boundary $h = 100 %$ (in brown) which is mapped from 3D scans of the experimental setup in E66 (A) and E78 (B). At the top boundary $h$ is fixed to $h = 70 %$ which was the average value of humidity in our experimental room. Note that $h$ is the relative humidity, thus the magnitude of the humidity gradient $| \nabla h |$ is measured in ${mm}^{- 1}$ , i.e $| \nabla h | = 0.1 {mm}^{- 1}$ means a humidity variation of 10% over $1 mm$ . Each contour corresponds to a variation of $0.015 {mm}^{- 1}$ . 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 $1 cm$ .

Appendix 1—figure 1

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Sketch of curvature definition on a saddle shaped surface.

Appendix 2—figure 1

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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

Additional files

MDAR checklist: https://cdn.elifesciences.org/articles/86843/elife-86843-mdarchecklist1-v1.pdf
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Giulio Facchini
Alann Rathery
Stéphane Douady
David Sillam-Dussès
Andrea Perna

(2024)

Substrate evaporation drives collective construction in termites

eLife 12:RP86843.

https://doi.org/10.7554/eLife.86843.4

Figures

Experimental setup.

Close-up on pillar structures built by our captive colony of Coptotermes gestroi within the plastic barrel that hosts the full colony.

Temperature (blue) and humidity (red) within the Petri dish as a function of time.

Experimental results - heatmaps.

Laboratory experiments and simulations of the growth model.

Snapshots of experiments with pillar cues.

Snapshots of experiments with wall cues.

Snapshots of experiments with no cues.

Diffusive simulations and chemical garden experiments.

Sketch of curvature definition on a saddle shaped surface.

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

Summary table of experiments.

Additional files

MDAR checklist

Download links

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

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Experimental setup.

Close-up on pillar structures built by our captive colony of Coptotermes gestroi within the plastic barrel that hosts the full colony.

Temperature (blue) and humidity (red) within the Petri dish as a function of time.

Experimental results - heatmaps.

Laboratory experiments and simulations of the growth model.

Snapshots of experiments with pillar cues.

Snapshots of experiments with wall cues.

Snapshots of experiments with no cues.

Diffusive simulations and chemical garden experiments.

Sketch of curvature definition on a saddle shaped surface.

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.

Summary table of experiments.

MDAR checklist

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)