# Building behaviour analyzed by X-rays tomography in two subterranean termite species

Éric Darrouzet, Laurence Berville, Armel Laot, Marie Legeais,
Anne-Geneviève Bagnères

► To cite this version:

Éric Darrouzet, Laurence Berville, Armel Laot, Marie Legeais, Anne-Geneviève Bagnères. Building behaviour analyzed by X-rays tomography in two subterranean termite species. IV Congrès Européen de l'IUSSI, Aug 2008, La Roche en Ardenne, Belgium. . hal-03873196

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Submitted on 26 Nov 2022

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<figure><img src="image_1.png" /></figure>

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# Building behaviour analyzed by X-rays tomography in two subterranean termite species.

E. Darrouzet<fnref n="1" />, L. Berville<fnref n="1" />, A. Laot<fnref n="2" />, M. Legeais<fnref n="2" /> & A-G Bagnères<fnref n="1" />

<figure><img src="image_2.png" /><figcaption>3D view of chambers in the wood.</figcaption></figure>

Reticulitermes species are **subterranean termites** which are found in natural and urban area in Europe. Because of their cryptic life, it is difficult to analyze colony sizes and constructions elaborated in soil and/or pieces of wood, i.e., numbers of chambers, structures elaborated in mud inside the wood, etc. By using **X-rays tomography**, a non invasive medical imaging technique, we were able to perform an original study on these different parameters in the lab.

We analyzed **wood consumption strategies** (volumes of wood eaten, kinetic of consumption, how termites colonized the piece of wood) and **building behaviour** by two termite species, *Reticulitermes grassei* and *R. santonensis*.

## Materials & methods

- 5 different **micro-colonies** are analyzed for each species

- 900 **workers/colony** in each plastic box (18 x 12 x 7 cm)

- a piece of wood (pinus: 12 x 4 x 4 cm)

- 2 mm of sand in the bottom

During one year, colonies were analyzed by X-rays tomography.

- Parameters : 120 kev, 180 mAs

- Thickness : 0.67 mm

- Increment : 0.33 mm

<figure><img src="image_3.png" /></figure>

## X-rays tomography

<figure><img src="image_4.png" /></figure>

Phillips Brilliance CT 40

Analyses were performed with a scanner (X-rays tomography).

Data were analyzed with the OsiriX software.

<figure><img src="image_5.png" /></figure>

chambers

2D view of a piece of wood with chambers containing living termites.

<figure><img src="image_6.png" /></figure>

sand

<caption>3D view of chambers in the wood</caption>

Piece of wood colonized by termites.

## Wood consumption

<figure><img src="image_7.png" /></figure>

*R. santonensis* consumes more wood than *R. grassei*
(Mann-Whitney: U=440261, P<0.001) during 258 days.

## Building behaviour

<figure><img src="image_8.png" /></figure>

Worker in
action.

<figure><img src="image_9.png" /></figure>

R. santonensis

Volume in cm³

The number of structures built in chambers is **correlated** to the volume of wood consumed (Pearson correlation: r=0.846, P=9.88x10⁻⁶).

## Different structures built in the wood

<figure><img src="image_10.png" /></figure>

During the experiment, **only** *R. santonensis* **workers** built mud structures in chambers.

Different mud structures are built inside the chambers in the wood: **caps, pillars, floors and walls**.

## CONCLUSION

- X-rays tomography is a fantastic tool to study insects' architectures and building behaviour in continue.

- For the first time, wood consumption and building behaviour of living subterranean termites were observed *in situ* during one year.

- In our conditions, the two species present great behavioural differences, as *R. santonensis* (1) eats more wood than *R. grassei* and (2) is the one who elaborates mud structures inside the wood.

- Our results confirm previous observations than *R. santonensis*, an invasive species introduced in France 300 years ago, makes more damages than *R. grassei*.

<footnote n="1">¹ University of Tours, IRBI, Parc de Grandmont, 37200 Tours, France.</footnote>

<footnote n="2">² CHRU of Tours 2 bd Tonnellé, 37044 Tours, France.
(eric.darrouzet@univ-tours.fr).</footnote>