SUMMARYOver the last decade, the lattice Boltzmann method (LBM) has evolved into a valuable alternative to continuum computational uid dynamics (CFD) methods for the numerical simulation of several complex uid-dynamic problems. Recent advances in lattice Boltzmann research have considerably extended the capability of LBM to handle complex geometries. Among these, a particularly remarkable option is represented by cell-vertex ÿnite-volume formulations which permit LBM to operate on fully unstructured grids. The two-dimensional implementation of unstructured LBM, based on the use of triangular elements, has shown capability of tolerating signiÿcant grid distortions without su ering any appreciable numerical viscosity e ects, to second-order in the mesh size. In this work, we present the ÿrst three-dimensional generalization of the unstructured lattice Boltzmann technique (ULBE as unstructured lattice Boltzmann equation), in which geometrical exibility is achieved by coarse-graining the lattice Boltzmann equation in di erential form, using tetrahedrical grids. This 3D extension is demonstrated for the case of 3D pipe ow and moderate Reynolds numbers ow past a sphere. The results provide evidence that the ULBE has signiÿcant potential for the accurate calculation of ows in complex 3D geometries.

The Argentine ant, Linepithema humile, is native to South America but has become one of the most invasive species in the world. These ants heavily rely on trail pheromones for foraging, and previous studies have focused on such signals to develop a strategy for chemical control. Here, we studied the effects of pre-exposure to the trail pheromone on sugar acceptance and olfactory learning in Argentine ants. We used the synthetic trail pheromone component (Z)-9-hexadecenal, which triggers the same attraction and trail-following behavior as the natural trail pheromone. We found that pre-exposure to (Z)-9-hexadecenal increases the acceptance of sucrose solutions of different concentrations, thus changing the ants’ subjective evaluation of a food reward. However, although ants learned to associate an odor with a sucrose reward, pheromone pre-exposure affected neither the learning nor the mid-term memory of the odor-reward association. Taking into account the importance of the Argentine ant as a pest and invasive organism, our results highlight the importance of pheromonal cues in resource evaluation, a fact that could be useful in control strategies implemented for this species.