Robotic Ants Successfully Mimic Real Colony Behavior

ORIGINAL: Science Daily

This image shows the robot ants (Alices) pursuing a light trail around the constructed maze. (Credit: Simon Garnier: Garnier S, Combe M, Jost C, Theraulaz G (2013) Do Ants Need to Estimate the Geometrical Properties of Trail Bifurcations to Find an Efficient Route? A Swarm Robotics Test Bed. PLOS Comput Biol 9(3): e1002903. doi:10.1371/journal.pcbi.1002903. CC)This image shows the robot ants (Alices) pursuing a light trail around the constructed maze. (Credit: Simon Garnier: Garnier S, Combe M, Jost C, Theraulaz G (2013) Do Ants Need to Estimate the Geometrical Properties of Trail Bifurcations to Find an Efficient Route? A Swarm Robotics Test Bed. PLOS Comput Biol 9(3): e1002903. doi:10.1371/journal.pcbi.1002903. CC)

Mar. 28, 2013 — Scientists have successfully replicated the behaviour of a colony of ants on the move with the use of miniature robots, as reported in the journal PLOS Computational Biology. The researchers, based at the New Jersey Institute of Technology (Newark, USA) and at the Research Centre on Animal Cognition (Toulouse, France), aimed to discover how individual ants, when part of a moving colony, orient themselves in the labyrinthine pathways that stretch from their nest to various food sources.

The study focused mainly on how Argentine ants behave and coordinate themselves in both symmetrical and asymmetrical pathways. In nature, ants do this by leaving chemical pheromone trails. This was reproduced by a swarm of sugar cube size robots, called "Alices," leaving light trails that they can detect with two light sensors mimicking the role of the ants' antennae.

In the beginning of the experiment, where branches of the maze had no light trail, the robots adopted an "exploratory behaviour" modelled on the regular insect movement pattern of moving randomly but in the same general direction. This led the robots to choose the path that deviated least from their trajectory at each bifurcation of the network. If the robots detected a light trail, they would turn to follow that path.

One outcome of the robotic model was the discovery that the robots did not need to be programmed to identify and compute the geometry of the network bifurcations. They managed to navigate the maze using only the pheromone light trail and the programmed directional random walk, which directed them to the more direct route between their starting area and a target area on the periphery of the maze. Individual Argentine ants have poor eyesight and move too quickly to make a calculated decision about their direction. Therefore the fact that the robots managed to orient themselves in the maze in a similar fashion than the one observed in real ants suggests that a complex cognitive process is not necessary for colonies of ants to navigate efficiently in their complex network of foraging trails.

"This research suggests that efficient navigation and foraging can be achieved with minimal cognitive abilities in ants," says lead author Simon Garnier. "It also shows that the geometry of transport networks plays a critical role in the flow of information and material in ant as well as in human societies."

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Journal Reference:

Simon Garnier, Maud Combe, Christian Jost, Guy Theraulaz. Do Ants Need to Estimate the Geometrical Properties of Trail Bifurcations to Find an Efficient Route? A Swarm Robotics Test Bed. PLoS Computational Biology, 2013; 9 (3): e1002903 DOI: 10.1371/journal.pcbi.1002903

Eciton burchellii, the swarm raider

ORIGINAL: Myrmecos.net

Feb 7th, 2011

by myrmecos. 

Eciton burchellii is, according to Wikipedia, “the archetypal species of army ant“. Insofar as this is the most-studied species, and the ant that dominates the nature documentaries, I suppose the moniker is true. 

Yet, the biology of E. burchellii is not terribly representative of army ants. It is an outlier, an ant whose behavior has diverged in significant ways from its relatives, even from its congeners. 

media and minor workers stream towards the front 

The primary difference is gustatory. Most army ants boast a fine-tuned pallate, favoring the brood of particular ant genera. E. burchellii is vulgar by comparison. It’ll eat just about any sort of animal protein. Spiders? Katydids? Lizards? Termites? Ants? They’re all good. 

a submajor worker carries a spider 

media workers pull a termite from a rotting log 

Corresponding to the broad diet, Eciton burchellii‘s foraging behavior is a radical departure from the army ant norm. For being an “archetypal” army ant, its raids ironically lack the military precision of other species. 

An overhead depiction of an Eciton burchellii swarm raid (from Rettenmeyer 1963) 

Instead of tight, focused columns that concentrate the ants’ efforts at a single point at the raid front, E. burchellii’s raids are messy, diffuse affairs. Foragers spread out in a swarm, casting a vicious stinging, biting net for animals too slow to escape. The strategy isn’t great for capturing concentrated food sources like another ant colony, but it works well for a generalist’s lunch. 

Raids set out in the morning with a swarm front near the overnight bivuoac. As the day progresses, the swarm moves through the forest for a distance about that of a football field. The back end of the swarm organizes into a series of converging trails to funnel captured prey back to the bivouac, so that by mid-day the swarm from above looks rather like the figure at left. Last night’s video featured one such trail. By nightfall the ants are back in the bivuoac, where, depending on the development of their larvae, they either regroup to march to a new bivouac site by morning, or they stay put and launch a new raid in a different direction the following day. 

Eciton burchellii raids are fascinating to watch, but they aren’t indicative of how most army ants behave. The fame of this one species is partly an artifact of the degree to which its unique biology intersects with the cognitive quirks of our own species. 

These ants are large, they forage above ground, and their sprawling raids cover extensive areas. And they raid primarily during the day, when we humans tend to walk about in the forest. That they catch our attention may be due as much to our biology as to theirs. 

[photos 1,2,4 taken at Jatun Sacha; 3,5 at Maquipucuna]

Megacolonia de hormigas argentinas ha colonizado el mundo

ORIGINAL: Pijamasurf

La hormiga argentina se expande por todos los rincones del planeta conformando una sola megacolonia; hay miles de millones de ellas, la clave de su éxito: la no-agresividad

Source: PNAS. Figure 1. Known worldwide distribution of the Argentine ant. Numbered black circles indicate introduced populations while shaded circles represent presumed native populations. See Table 1 for sources of information, estimated dates of introduction, and a brief discussion of some records for each number and letter.

Por años pensamos que el hombre y las ratas éramos las únicas especies capaces de poblar el mundo entero, sin embargo esto no es así. De acuerdo con un grupo de científicos de Japón y España, encabezados por Eiriki Sunamura de la Universidad de Tokyo, las hormigas argentinas que habitan en América, Europa y Japón pertenecen a la misma colonia y no pelean entre sí. Todo indica que una gran familia de hormigas lucha hombro con hombro por la dominación del planeta, junto con los seres humanos.

Las hormigas argentinas (Linepithema humile) son nativas de Sudamérica pero irónicamente fue el hombre el que se encargó de llevarlas a todos los continentes del mundo, salvo la Antártida. La hormiga argentina, junto con el hombre, se ha convertido en la peor plaga del planeta.

De acuerdo con los científicos, en Europa existe una gran colonia de estas hormigas que ocupa una franja de 6,000 km a lo largo de la costa mediterránea, existe otra en California que ocupa una extensión de 900 km y otra en la costa oeste de Japón, en Kobe.

A diferencia del nosotros, las hormigas argentinas, que tal vez comparten la adaptabilidad a tierras foráneas de los humanos de su país, no muestran señales de agresividad entre sí, se reconcoen por señales químicas emanadas de sus cutículas, frotan su antena en camaradería y no intentan evitarse.

La clave de su éxito es que a diferencia de otras especies de hormigas, las hormigas argentinas no luchan entre sí y viven en respetuosa armonía. Sin agresividad. conectadas por una mente comunal urdiendo un plan maestro del cual, como en un holograma, cada una es parte indisiociable. Suena interesante.Tal vez las hormigas argentinas nos puedan enseñar el significado del sueño cliché de la paz mundial o, un equivalente: “Mi sueño es que todos nos convirtamos en hormigas”.