Biologists and mathematicians have modeled the nest construction of termites of the genus Nasutitermes has been found that termites build tunnels in accordance with the local curvature of the surface, with the characteristic thickness of the tunnel about the size of a termite. Article published in the journal Journal of the Royal Society Interface.
Termites and other social insects such as ants, build nests for the protection of the colony. About ants, scientists know, for example, that during the construction they respond to flows of carbon dioxide, the crowd and attract more ants with pheromones, so there are wide hallways. While the movement of individual insect is very difficult to describe, ant raises and lowers the grain of building material in accordance with local state of the environment — in the case of a large colony stigmergetic effects (e.g., spraying of pheromones) make the largest contribution to the construction.
However, to observe the process of construction of the nests of the termite Nasutitermes only happened a couple of times — they build too unpredictable and fast. By observations for building the nest in laboratory conditions, scientists have discovered that the surface of the walls of the tunnel has the shape of a saddle, suggesting that the Golden rule of construction of termite mounds: in a region with a large curvature of the surface of the termites build walls (and reduce the curvature), and in the field with a small curvature of the surface doing nothing. Furthermore, other termite Macrotermes michaelseni scientists found a positive correlation between the curvature of the surface and the activity of the insects.
Scientists from Belgium, UK and France under the leadership of Giulio of Faccini (Giulio Facchini) at the University of Roehampton has developed a growth model nests arboreal termites Nasutitermes. Researchers in the approximation of the dominant stigmergy simplified model and considered not separate the effects of termites, but their result is conditional independent growth of the mound, depending on its form, particularly from the local curvature of the surface.
The researchers chose a specific kind of termites Nasutitermes due to the simplicity of their nests — they are isotropic and homogeneous (as the growth of nests occur in trees, the basic material are chips), causing different parts of the mound it is difficult to distinguish between them. Moreover, in the nest there are no specialized cavities, which is useful for initial verification of the theory of the construction of termite mounds. However, the authors correctly point out that local curvature is an indirect parameter that influences the building — for example, it can accumulate more “cement pheromone” or termites set of particles in accordance with the gradient of humidity, which may arise due to the different curvature of the surface. However, none of these reasons to the end is not justified.
In order to determine how evolyutsioniruet the mound, scientists had to solve the problem of two phases, construction material, and voids, with the changing boundary conditions. Analytically the problem was solved only in the planar case, however, in an alternative approach, you can replace the substrate and empty environment for a scalar field, from which it is possible to form the surface of the walls — the boundaries between phases. The researchers then suggested the dependence of the field from the time in which we can distinguish two terms: linear growth and diffusion, which corrects the behavior of this scalar field at points with a large curvature of the surface. After analyzing the behavior of the subject, the researchers came to the conclusion that the diffusion member blurs all the details of the construction of particles with dimensions less than the thickness of the wall. Because of this, beyond the model is the porosity, which provides the necessary ventilation for the nest.