Walking kinematics of ants carrying food in the mandibles versus gaster.

The locomotor behavior of an animal strongly depends on the distribution of its body mass. Whenever changes occur in this distribution, the displacement of the body center of mass (CoM) may lead to a loss of balance. Ants are an interesting biological model with which to investigate how an animal copes with such changes because, when they transport food, their CoM may be displaced from its usual position.

Overwintering aggregation patterns of European catfish Silurus glanis.

Animal aggregation, particularly in large-bodied species, is both a fascinating and intriguing phenomenon. Here we analyzed the overwintering behavior of the European catfish, Silurus glanis Linnaeus, 1758, the largest freshwater fish in Europe. By tracking 47 subadults and adults in a shallow lake in southeastern France, we reported a consistent aggregative behavior across four successive winters.

Biomechanical effects of the addition of a precision constraint on a collective load carriage task.

Team lifting is a complex and collective motor task comprising motor and cognitive components. The purpose of this research is to investigate how individual and collective performances are impacted during load transport combined with a cognitive task. Ten dyads performed a first condition in which they transported a load (CC), and a second one in which they transported the load while maintaining a ball on its top (PC).

A biomechanical study of load carriage by two paired subjects in response to increased load mass.

The biomechanics of load carriage has been studied extensively with regards to single individuals, yet not so much with regards to collective transport. We investigated the biomechanics of walking in 10 paired individuals carrying a load that represented 20%, 30%, or 40% of the aggregated body-masses. We computed the energy recovery rate at the center of mass of the system consisting of the two individuals plus the carried load in order to test to what extent the pendulum-like behavior and the economy of the gait were affected.

Dynamics of locomotion in the seed harvesting ant effect of individual body mass and transported load mass.

Ants are well-known for their amazing load carriage performances. Yet, the biomechanics of locomotion during load transport in these insects has so far been poorly investigated. Here, we present a study of the biomechanics of unloaded and loaded locomotion in the polymorphic seed-harvesting ant (Linnaeus, 1767).

Walking kinematics in the polymorphic seed harvester ant : influence of body size and load carriage.

Ants are famous in the animal kingdom for their amazing load-carrying performance. Yet, the mechanisms that allow these insects to maintain their stability when carrying heavy loads have been poorly investigated. Here, we present a study of the kinematics of unloaded and loaded locomotion in the polymorphic seed-harvesting ant In this species, large ants have larger heads relative to their size than small ants.

Locomotor pattern and mechanical exchanges during collective load transport.

While the locomotor behavior of humans walking alone, loaded or unloaded, has been extensively studied, the locomotor behavior of humans transporting a load collectively is very poorly documented in the biomechanics literature. Yet, collective carriage is a task commonly performed in sport (CrossFit), military and health care (carriage of an injured person) activities and is a task that raises growing interest in robotics (Cobots). The primary aim of our research was to test the hypothesis that the mechanical cost of locomotion is comparable when two individuals are transporting an object collectively and when they are walking alone.

Analysis of Gait During Independent and Paired Walking in Adults with an Intellectual Disability: A Case Report.

Objective: Gait rehabilitation is a major concern for adults with an intellectual disability or a neuropsychological disorder. This study evaluated a collective task exercise that could complement an individual rehabilitation routine in such individuals. The movements of 3 individuals (2 patients and 1 healthy individual) were measured while walking alone and in pairs.

Walking pattern efficiency during collective load transport.

Background: While the locomotor behavior of humans walking alone has been extensively studied, the locomotor behavior of humans transporting a load collectively is very poorly documented in the biomechanics literature. Yet, collective transport could find potential developments in other domains such as rehabilitation and robotics.

Research Question: If collective load transport is made economically one could expect that the center of mass of the ensemble formed by several individuals and the load they carry has the same pendulum-like behavior as a single individual walking alone.

Ergonomics of load transport in the seed harvesting ant Messor barbarus: morphology influences transportation method and efficiency.

We studied in the field the load transport behavior of workers of the polymorphic Mediterranean seed harvester ant Messor barbarus Individual ants used two different methods to transport food items: carrying and dragging. The probability of dragging instead of carrying varied significantly with both the mass of the item transported and its linear dimension. Moreover, the values of item mass and length at which dragging began to occur increased with increasing size of the workers.

Spatio-Temporal Dynamics of Foraging Networks in the Grass-Cutting Ant Atta bisphaerica Forel, 1908 (Formicidae, Attini).

Foraging networks are a key element for ant colonies because they facilitate the flow of resources from the environment to the nest and they allow the sharing of information among individuals. Here we report the results of an 8-month survey, extending from November 2009 to June 2010, of the foraging networks of four mature colonies of Atta bisphaerica, a species of grass-cutting ant which is considered as a pest in Brazil. We found that the distribution of foraging effort was strongly influenced by the landscape features around the nests, in particular by the permanently wet parts of the pasture in which the nests were located.

Lifespan behavioural and neural resilience in a social insect.

Analyses of senescence in social species are important to understanding how group living influences the evolution of ageing in society members. Social insects exhibit remarkable lifespan polyphenisms and division of labour, presenting excellent opportunities to test hypotheses concerning ageing and behaviour. Senescence patterns in other taxa suggest that behavioural performance in ageing workers would decrease in association with declining brain functions.

Dynamics of foraging trails in the Neotropical termite Velocitermes heteropterus (Isoptera: Termitidae).

Foraging behavior in termites varies with the feeding habits of each species but often occurs through the formation of well-defined trails that connect the nest to food sources in species that build structured nests. We studied the formation of foraging trails and the change in caste ratio during foraging in the termite Velocitermes heteropterus. This species is widespread in Cerrado vegetation where it builds epigeal nests and forages in open-air at night.

A preliminary checklist of the ants (Hymenoptera, Formicidae) of Andorra.

Within the last decade, checklists of the ant fauna of several European countries have been published or updated. Nevertheless, no ant checklists have hitherto been published for the principality of Andorra, a small landlocked country located in the eastern part of the Pyrenees. This work presents a critical list of the ant species of Andorra based on a review of the literature and on the biological material we collected during several field campaigns conducted in Andorra since the year 2005.

Key factors for the emergence of collective decision in invertebrates.

In many species of group living invertebrates, in particular arthropods, collective decisions can emerge from the combined actions of individuals and the direct or indirect interactions between individuals. These decisions allow groups of individuals to respond quickly and accurately to changes that occur in their environment. Examples of such decisions are found in a variety of invertebrate taxa and in many different contexts, e.

Individual rules for trail pattern formation in Argentine ants (Linepithema humile).

We studied the formation of trail patterns by Argentine ants exploring an empty arena. Using a novel imaging and analysis technique we estimated pheromone concentrations at all spatial positions in the experimental arena and at different times. Then we derived the response function of individual ants to pheromone concentrations by looking at correlations between concentrations and changes in speed or direction of the ants.

Ant traffic rules.

Many animals take part in flow-like collective movements. In most species, however, the flow is unidirectional. Ants are one of the rare group of organisms in which flow-like movements are predominantly bidirectional.

Individual and collective problem-solving in a foraging context in the leaf-cutting ant Atta colombica.

In this paper we investigate the flexibility of foraging behavior in the leaf-cutting ant Atta colombica, both at the individual and collective levels, following a change in the physical properties of their environment. We studied in laboratory conditions the changes occurring in foraging behavior when a height constraint was placed 1 cm above part of the trail linking the nest to the foraging area. We found that the size and shape of the fragments of foraging material brought back to the nest were significantly modified when the constraint was placed on the trail: independent of their size, forager ants cut smaller and rounder fragments in the presence of a height constraint than in its absence.

Are ants sensitive to the geometry of tunnel bifurcation?

The ability to orient and navigate in space is essential for all animals whose home range is organized around a central point. Because of their small home range compared to vertebrates, central place foraging insects such as ants have for a long time provided a choice model for the study of orientation mechanisms. In many ant species, the movement of individuals on their colony home range is achieved essentially collectively, on the chemical trails laid down by their nest mates.

Does substrate coarseness matter for foraging ants? An experiment with Lasius niger (Hymenoptera; Formicidae).

We investigated whether workers of the ant species Lasius niger are able to sense and discriminate the coarseness of the substrate on which they walk. First, we studied the way in which substrate coarseness affects the ants' locomotory behaviour. Second, we investigated the spontaneous preference of ants for substrates of different coarseness.

Path efficiency of ant foraging trails in an artificial network.

In this paper we present an individual-based model describing the foraging behavior of ants moving in an artificial network of tunnels in which several interconnected paths can be used to reach a single food source. Ants lay a trail pheromone while moving in the network and this pheromone acts as a system of mass recruitment that attracts other ants in the network. The rules implemented in the model are based on measures of the decisions taken by ants at tunnel bifurcations during real experiments.

Temporal organization of bi-directional traffic in the ant Lasius niger (L.).

Foraging in ants is generally organized along well-defined trails supporting a bi-directional flow of outbound and nestbound individuals and one can hypothesize that this flow is maximized to ensure a high rate of food return to the nest. In this paper we examine the effect of bottlenecks on the temporal organization of ant flow. In our experiments ants had to cross a bridge to go from their nest to a food source.

Amplification of individual preferences in a social context: the case of wall-following in ants.

Amplification processes are an essential component of the collective phenomena observed in social and gregarious species. In this paper, we tested the hypothesis that a weak individual wall-following tendency in ants can be amplified by communication through chemical trails, leading to a response to the spatial heterogeneities at the collective level. In our experiments, ants had to cross a diamond-shaped bridge along either of two branches of equal length to get from their nest to a food source.

Optimal traffic organization in ants under crowded conditions.

Efficient transportation, a hot topic in nonlinear science, is essential for modern societies and the survival of biological species. Biological evolution has generated a rich variety of successful solutions, which have inspired engineers to design optimized artificial systems. Foraging ants, for example, form attractive trails that support the exploitation of initially unknown food sources in almost the minimum possible time.

A model of animal movements in a bounded space.

Most studies describing animal movements have been developed in the framework of population dispersion or population dynamics, and have mainly focused on movements in open spaces. During their trips, however, animals are likely to encounter physical heterogeneities that guide their movements and, as a result, influence their spatial distribution. In this paper, we develop a statistical model of individual movement in a bounded space.