Traveling through light clutter: Path integration and panorama guided navigation in the Sonoran Desert ant, Novomessor cockerelli.

Foraging ants use multiple navigational strategies, including path integration and visual panorama cues, which are used simultaneously and weighted based upon context, the environment and the species' sensory ecology. In particular, the amount of visual clutter in the habitat predicts the weighting given to the forager's path integrator and surrounding panorama cues. Here, we characterize the individual cue use and cue weighting of the Sonoran Desert ant, Novomessor cockerelli, by testing foragers after local and distant displacement.

Pheromone cue triggers switch between vectors in the desert harvest ant, Veromessor pergandei.

The desert harvester ant (Veromessor pergandei) employs a mixture of social and individual navigational strategies at separate stages of their foraging trip. Individuals leave the nest along a pheromone-based column, travelling 3-40 m before spreading out to forage individually in a fan. Foragers use path integration while in this fan, accumulating a direction and distance estimate (vector) to return to the end of the column (column head), yet foragers' potential use of path integration in the pheromone-based column is less understood.

Same but different: Socially foraging ants backtrack like individually foraging ants but use different mechanisms.

Diverse species may adopt behaviourally identical solutions to similar environmental challenges. However, the underlying mechanisms dictating these responses may be quite different and are often associated with the specific ecology or habitat of these species. Foraging desert ants use multiple strategies in order to successfully navigate.

Not just going with the flow: foraging ants attend to polarised light even while on the pheromone trail.

The polarisation pattern of skylight serves as an orientation cue for many invertebrates. Solitary foraging ants, in particular, rely on polarised light to orient along with a number of other visual cues. Yet it is unknown, if this cue is actively used in socially foraging species that use pheromone trails to navigate.

Self-organizing conflicts: Group assessment and the spatio-temporal dynamics of ant territory battles.

Territorial battles among ants exhibit temporal and spatial patterns that self-organize, arising spontaneously from distributed decisions by large numbers of individuals. We describe agent-based models of inter-group fights in ants and show that two behavioral mechanisms that are rarely quantified have large effects on the dynamics of intraspecific battles; specifically, the pattern of search by unengaged ants, and assessment of relative numbers. In the absence of assessment, recruitment by both colonies rises to steady averages.

New exocrine glands in ants: the hypostomal gland and basitarsal gland in the genus Melissotarsus (Hymenoptera: Formicidae).

Fisher and Robertson (Insect Soc 46: 78-83, 1999) discovered the production of silk-like secretions emerging from slit-shaped openings along the anterior margin of the ventral hypostoma of Melissotarsus ant workers. The current histological study describes a hitherto unknown hypostomal gland from which this silk-like substance originates. In addition, this study describes a new basitarsal gland in the three pairs of legs of Melissotarsus workers.

Chemical communication during foraging in the harvesting ants Messor pergandei and Messor andrei.

We combined behavioral analyses in the laboratory and field to investigate chemical communication in the formation of foraging columns in two Nearctic seed harvesting ants, Messor pergandei and Messor andrei. We demonstrate that both species use poison gland secretions to lay recruitment trails. In M.

An empirically based simulation of group foraging in the harvesting ant, Messor pergandei.

We present an empirically based group model of foraging interactions in Messor pergandei, the Sonoran desert harvesting ant. M. pergandei colonies send out daily foraging columns consisting of tens of thousands of individual ants.

Pygidial gland chemistry and potential alarm-recruitment function in column foraging, but not solitary, Nearctic Messor harvesting ants (Hymenoptera: Formicidae: Myrmicinae).

We investigated the role of the pygidial gland on foraging behavior in two ecologically dominant column foraging Nearctic harvesting ants (Messor pergandei and Messor andrei). Using chemical analyses and behavioral tests, we show that n-tridecane is the major biologically active compound of pygidial gland secretions in both species, and that this chemical functions as a powerful alarm-recruitment pheromone. Another major compound of pygidial gland contents is benzaldehyde; this substance does not release behavioral reactions in M.

Metalloproteinase-dependent cleavage of neuregulin and autocrine stimulation of vascular endothelial cells.

Inflammation is often accompanied by robust angiogenesis. Vascular endothelial cells (ECs) express erbB receptors and their ligand, neuregulin-1, and can respond to neuregulin by proliferation and angiogenesis. We hypothesized that some growth factor-like responses of ECs to inflammatory cytokines can be explained by cleavage of transmembrane neuregulin with subsequent release of its extracellular epidermal growth factor-like-containing domain and autocrine activation.

An empirical test of Lanchester's square law: mortality during battles of the fire ant Solenopsis invicta.

Lanchester's models of attrition describe casualty rates during battles between groups as functions of the numbers of individuals and their fighting abilities. Originally developed to describe human warfare, Lanchester's square law has been hypothesized to apply broadly to social animals as well, with important consequences for their aggressive behaviour and social structure. According to the square law, the fighting ability of a group is proportional to the square of the number of individuals, but rises only linearly with fighting ability of individuals within the group.