Las hormigas preparan un coctel de antibiótico para proteger la colonia.

Wood ants combine tree resin with formic acid to protect their nests from fungi and bacteria.

Simon Williams/Minden Pictures


‘Chemist’ ants brew antibiotic cocktail to protect their colony

Ants have all sorts of jobs we normally think of as human, from architect to farmer to insect-in-chief. Now, scientists are adding one more occupation to that list: chemist. A new study shows that wood ants protect their colonies from disease by crafting a potent antibiotic “cocktail” made of tree resin and poison from their own bodies. The finding, one of the most sophisticated examples of animal pharmacology, could explain how some ants evade epidemics.

Like humans, wood ants (Formica paralugubris) live in dense groups, with colonies numbering in the hundreds of thousands. That should make them prime targets for widespread disease, especially because their nests are warm, humid, and full of dead insects to be used as food. Most ant species manage to avoid epidemics by grooming each other and obsessively cleaning their colonies, and wood ants take the added precaution of collecting antimicrobial tree resin to bring back to their nests. But Michel Chapuisat, an evolutionary biologist at the University of Lausanne in Switzerland, suspected this species might be hiding an even more sophisticated secret for staying healthy.

To investigate, Chapuisat and his colleagues first measured how well wood ant–exposed resin warded off a deadly fungus—which infects ants and spreads through spores grown in their bodies—compared to tree resin alone. In petri dishes covered with the fungus (Metarhizium brunneum), resin stored with the ants for 2 weeks resulted in a 50% larger fungus-free area, the team reports this month in Ecology and Evolution. Stones and twigs, both common in nests, didn’t get any antifungal boost from being around the ants. That was an indication that something special was happening between wood ants and resin.

Next, the researchers used liquid chromatography, a technique for analyzing chemical mixtures, to spot any substances left behind by the wood ants. One compound they found was formic acid: a caustic substance produced by several ant species to fight off threats, subdue prey, and clean their offspring. When the scientists dipped tree resin in the acid, they found the resulting mixture did a better job of warding off fungus than resin alone, or glass dipped in formic acid. That was enough for the researchers to confirm the ants are mixing the two substances—one found, one created—to keep their nests healthy. “They exploit the tree and then they combine it with their own poison,” Chapuisat explains.

“I thought it was a really interesting and exciting paper,” says Michael Singer, an evolutionary ecologist at Wesleyan University in Middletown, Connecticut. Plenty of animals defend themselves with substances they find or create, but Singer says this new substance shows unique “synergistic effects,” meaning that the mixture of resin and formic acid is more than just the sum of its parts. The only other example of an animal brewing up a combination like this—which Singer calls “defensive mixology”—is humans and our drug cocktails.

But rather than springing suddenly from the mind of a brilliant human inventor, this mixture is the result of a long evolutionary tug-of-war. “Ants have been coevolving with their pathogens for 50 million years,” and perhaps longer, says Christopher Pull, an evolutionary biologist at the Institute of Science and Technology Austria in Klosterneuberg. And for now, the insects seem to be keeping their microbes at bay. With issues like antibiotic resistance making human drugs less effective, Pull says the time-tested strategies of ants may be worth a closer look. “Maybe they’ve come up with viable solutions to these problems we’re just now encountering.”

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Toman decisiones las hormigas obreras?

Organización de hormigas

POR PATRICIA OLIVELLA

En el marco del Grupo de Estudio de Insectos Sociales, un equipo liderado por Roxana Josens investiga la forma en que recolectan su alimento las hormigas carpinteras. Los dos elementos centrales de sus estudios apuntan a entender de qué manera toman las decisiones cada una de las obreras y cómo funcionan los canales de comunicación que se establecen entre ellas.


Hormigas carpinteras se alimentan de una solución azucarada. Foto: Diana Martinez Llas.

Hormigas carpinteras. Foto Diana Martinez Llas.

Habitan el planeta desde hace más de cien millones de años. Se las puede ver en el jardín, la calle, la cocina, casi en cualquier parte. Su laboriosidad las convirtió en protagonistas de comparaciones elogiosas y películas como Bichos o Antz contribuyeron a exaltar su notable organización social. No es de extrañar, entonces, que en el marco del Grupo de Estudio de Insectos Sociales (Ver el Cable 685), un equipo liderado por Roxana Josens se dedique a investigar la forma en que recolectan su alimento ciertas hormigas.

El Grupo de Insectos Sociales está formado por dos equipos: uno que estudia las abejas (otro insecto social), dirigido por Walter Farina, y el que se dedica a las hormigas. “Nuestro equipo centra sus investigaciones en la forma en que recolectan recursos las nectívoras, hormigas en las que las soluciones azucaradas representan una parte importante de la dieta”, se presenta Josens.


Los investigadores estudian la forma en la que las hormigas carpinteras ingieren el néctar y cómo ésta puede ser modificada tanto por factores internos (propios del insecto), como externos (propios del mismo recurso y del ambiente). “Estudiamos también cómo se organiza la recolección en estos insectos. No existen líderes ni jerarquías en los grupos cooperativos”, explica Josens. “La clave de la organización grupal en la realización de las tareas radica en la toma de decisiones de cada obrera y los canales de comunicación que se establecen entre ellas. Por eso estos dos elementos son los ejes centrales de nuestros estudios”, agrega.

Las experiencias previas del individuo afectan la toma de decisiones; por eso, hace algunos años, los especialistas iniciaron una línea de investigación sobre memoria y aprendizaje. “Estudiamos la utilización de claves olfativas ajenas a la colonia durante la recolección de néctar, y las memorias asociativas que vinculan estos dos estímulos: olor-azúcar. Estas asociaciones podrían establecerse naturalmente cuando una hormiga visita repetidamente una fuente de alimento; el olor que percibe al aproximarse al recurso, con las sucesivas visitas, le anticipa el encuentro con la recompensa buscada. Al reproducir esta situación en laboratorio, con un laberinto en forma de Y, las hormigas mostraron ser capaces de establecer memorias asociativas de largo término. También en el contexto social del reclutamiento, la hormiga que prueba el néctar que otra le ofrece en un contacto boca a boca, o trofalaxia, puede aprender su olor y luego orientarse en la fuente de alimento siguiendo el olor aprendido”, detalla la investigadora.

El Grupo realiza la mayor parte de su trabajo en el laboratorio, donde crían colonias de hormigas en nidos artificiales. Mediante dispositivos sencillos, hacen que las hormigas recolecten recursos en un sitio determinado. De esta forma, las hormigas ingieren una solución azucarada, vuelven al nido donde descargan por medio de trofalaxias, reclutan más recolectoras, e inician otro ciclo de recolección sin ser perturbadas. Aunque parezca una tarea imposible, los investigadores pesan a la hormiga antes y después de que ingiera el alimento para determinar cuánto cebo azucarado llevó en su buche y distribuyó entre sus compañeras dentro del nido.

A partir de los estudios de comportamiento Josens comenta: “Las hormigas pueden aceptar o no una solución azucarada, cargar poco o a repleción, reclutar o no, tomar más rápido o más lentamente, modulando estas variables de acuerdo al valor que tiene ese recurso para la colonia en ese momento. Estos datos no son menores, ya que la utilización de cebos azucarados adicionados con algún tóxico es lo más recomendado para combatir la mayoría de las especies en el ambiente urbano, particularmente en domicilios y hospitales”. Josens y su equipo llevan algunos años estudiando el control químico de hormigas por ingestión de cebos tóxicos. “Hemos visto que algunas especies rechazan algunos compuestos activos en particular y otras especies rechazan otros, aunque ambas tengan similares hábitos alimentarios. Es por eso que estudiamos de qué manera inducir una mayor aceptación de los cebos tóxicos cuando son rechazados, aprovechando los comportamientos naturales de estos insectos; por ejemplo, las memorias olfativas. En el laboratorio, una hormiga que aprendió un olor al ser reclutada, luego acepta más e ingiere mayor cantidad de un cebo tóxico si éste presenta el mismo olor”.

Gran parte de los resultados obtenidos a partir de la investigación básica fueron incorporados en protocolos de control químico de hormigas urbanas y probados en un hospital y en domicilios con resultados muy satisfactorios. “Continuamos trabajando en el laboratorio para mejorar la estabilidad de los cebos y los procedimientos de aplicación, y para contrarrestar el rechazo que generan algunos compuestos”, afirma Josens, quien reafirma el objetivo de transferir directamente los resultados obtenidos en laboratorio al control de hormigas hospitalarias.

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Mas cámaras en un hormiguero significa mas comida para la colonia. (Inglés)

More tunnels in ant nests means more food for colony

Source:
University of California – San Diego
Summary:
A study of the underground ‘architecture’ of harvester ant nests has found that the more connected the chambers an ant colony builds near the surface entrance, the faster the ants are able to collect nearby sources of food.
FULL STORY

Harvester ant with seed.

Credit: Noa Pinter-Wollman/UC San Diego


 A UC San Diego study of the underground “architecture” of harvester ant nests has found that the more connected the chambers an ant colony builds near the surface entrance, the faster the ants are able to collect nearby sources of food.

The reason is simple: Increased connectivity among chambers leads to more social interactions among the ants within the nest. So when one group of ants within a colony–comprised of individuals working toward a common goal–finds a particularly good source of food, it’s able to more quickly communicate that finding to the rest of the colony.

“The volume of the chambers has little influence on the speed of recruitment, suggesting that the spatial organization of a nest has a greater impact on collective behavior than the number of workers it can hold,” said Noa Pinter-Wollman, a biologist at UC San Diego who conducted the study, which was published in this week’s issue of the journal Biology Letters.

Because these nests are occupied by extremely cooperative societies, she believes they can potentially inspire architectural designs that promote collaboration among humans.

“One straightforward lesson that will probably not surprise many architects is that having more corridors connecting offices or rooms will facilitate easier movement of people among them, both promoting interactions and expediting evacuation in emergency,” she said. “However, a less obvious potential addition to this lesson would be that increasing the connectivity of locations with an important function, such as break rooms, where people interact–similar to the entrance chamber of the ants–could increase interactions and collaborations.”

Noa Pinter-Wollman, a research scientist at UC San Diego’s BioCircuits Institute, found that as both the connectivity of chambers within the ant nests and the redundancy of connections among chambers increase, so does a colony’s speed of recruitment to food. Using a form of mathematical analysis known as “network theory,” she analyzed the structures of different ant nests and related them to the collective behavior of the colonies residing in them–in this case, the foraging of harvester ants.

These native species of ants, known to scientists as Veromessor andrei, live in grasslands and chaparral throughout California, including San Diego. They frequently move into existing nests abandoned by other colonies that built those nests when they were young or “renovated” them after a rainstorm loosened the soil. The ants feed on seeds they collect from the ground or directly from plants, but will also bring back to their nests larger food items such as termites or caterpillars.

“My earlier work on this ant species showed that colonies change their collective behavior as they relocate among nest sites,” said Pinter-Wollman. “I wanted to know what causes this change in behavior and one likely hypothesis was that the behavioral change was closely related to the nest site.”

Studies conducted recently by other scientists had determined that finding food quickly was critical to the reproductive success of harvester ants. So Pinter-Wollman measured how rapidly ants were able to recruit their nest mates to a small piece of apple placed 10 to 15 centimeters from the entrance of 106 nest sites in the Elliot Chaparral Reserve near the UC San Diego campus.

With the assistance of two UC San Diego undergraduate environmental systems students, Annamarie Go and James Huettner, she tracked 28 harvester ant colonies, some of which occupied several nest sites. The team then obtained both behavioral data and plaster casts (which revealed the underground chambers and other structures) of 32 nest sites occupied by 17 different ant colonies.

Pinter-Wollman said her study was the first to find a link between a “naturally occurring nest architecture and the collective actions of the colony that resides in it.” While more interconnected chambers near the entrance to the nest provides an advantage to food recruitment, she noted that there is also a downside to having too many chambers near the surface. Such an architecture could introduce structural instabilities that would cause the chambers to collapse during rains when the ground is softened, she noted.

“After a prolonged drought like the one we’re experiencing in California, severe storms, such as those anticipated later this year, could cause flooding and destroy these upper structures,” she said. “It would be interesting to see if, after the predicted El Niño, harvester ants build deeper chambers than they have in previous years.”

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Porqué algunas mariposas hacen el mismo ruido que las hormigas. (Inglés)

Why some butterflies sound like ants

Source:
Acoustical Society of America (ASA)
Summary:
Ant nests can offer a lot to organisms other than just ants. They are well-protected, environmentally-stable and resource-rich spaces — in many ways everything a tiny creature could ask for in a home. For the insects that squat inside ant nests, though, survival means finding ways to live with the ants — by foiling the chemical cues ants use to distinguish friend from foe, for instance.
FULL STORY

Parasitic butterfly larvae may use acoustic signals to infiltrate ant colonies.

Credit: Marco Gherlenda/University of Turin, Italy


Ant nests can offer a lot to organisms other than just ants. They are well-protected, environmentally-stable and resource-rich spaces — in many ways everything a tiny creature could ask for in a home. So long as you can live with an army of ants of course.

For the thousands of species of insects that squat inside ant nests, survival means finding ways to live with the ants — by foiling the chemical cues ants use to distinguish friend from foe, for instance. Now a team of scientists from the University of Turin in Italy have been looking at how the would-be nest crashers also use sound as a protective countermeasure — warping ant “words” to suit their own twisted tastes.

At the 168th Meeting of the Acoustical Society of America (ASA), to be held October 27-31, 2014 at the Indianapolis Marriott Downtown Hotel, the researchers will describe the latest research on one such ant-parasite pair — Maculinea butterflies, which infiltrate the nests of Myrmica ants and spend most of their lives there as unwanted guests by mimicking the sounds produced by the ants themselves.

“Acoustic signals convey quite complex information, not only between worker ants while outside the colony, for example during foraging, but also within the nest and between castes,” said Francesca Barbero, the lead researcher from the University of Turin, Italy. “We aimed at understanding whether some ant social parasites, such as butterfly larvae, could interfere with their host ant communication system.”

Over the years, Barbero’s team has recorded and analyzed the sound signals emitted by larvae and pupae of Maculinea parasites and by queens and workers of the Myrmica host ants. Observing similarities in the patterns between butterfly parasites and ant host’s acoustic signals, they have investigated the role of those signals in the ant societies and host-parasite relationships by playing back recorded sounds to ant nests.

In an initial study published in the journal Science in 2009, Barbero’s team collaborated with scientists from the Center for Ecology and Hydrology and the University of Oxford to show that the sounds queen ants make are distinctive sounds from worker ants inside ant colonies. The new work shows that the parasitic butterflies exploit that difference.

Maculinea species are so-called “obligated parasites,” Barbero said, with lives that depend on two other species. Deposited as eggs onto the leaves or buds of one specific plant, they gorge themselves for 10-15 days then drop to the ground and wait to be found and ferried into a nest by a Myrmica worker ant.

Earlier research in the field showed that the butterfly caterpillars can “beg” like baby ants by secreting chemicals similar to those an ant larva would, fooling the workers into feeding the caterpillars as their own. But some of these imposing guests were actually given the royal treatment — fed first and fed most, even in times of scarcity as the real ant larvae went hungry. This type of privilege is normally reserved for the queens of the nest, something that mimicking the begging brood could not account for.

To solve the mystery, Barbero and colleagues used a specially-manufactured microphone to record the noises of the ants and the caterpillars and played back the caterpillars’ sounds within ant nests. By comparing the acoustic signals and analysing the responses of the ants, they found that the caterpillars indeed mimic the sound of their host queen ants and trick the worker ants into cleaning and feeding them in preference to their own offspring.

They also compared two populations of parasitic butterflies — a predatory species that feeds on ant broods, and a cuckoo species that is fed directly by the worker ants. They found that while both species made queen sounds, the voices of the ones that depended on workers to feed them elicited a stronger response in the worker ants.

“This is consistent,” Barbero said. “Once inside the host nest, the main difference between the two life strategies is that cuckoos need to be considered as colony members, predatory species need not to be discovered by ants.”

The next step, she said, is to extend their research to assess the role of acoustical emissions in other butterfly-ant interactions.

“We hope our findings will boost research on acoustic communication in social parasites of ants,” Barbero said, “[and] bring about significant advances in our understanding of the complex mechanisms underlying the origin, evolution and stabilization of host-parasite relationships.”

Presentation 3aAB1, “Breaking the acoustical code of ants: The social parasite’s pathway,” by Francesca Barbero, Luca P. Casacci, Emilio Balletto and Simona Bonelli will take place on October 29, 2014.

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Como se organizan las hormigas para hacer sus hormigueros

How ants self-organize to build their nests

Summary:
Ants collectively build nests whose size can reach several thousand times that of individual ants and whose architecture is sometimes highly complex. However, their ability to coordinate several thousand individuals when building their nests remains a mystery. To understand the mechanisms involved in this process, researchers combined behavioral analysis, 3D imaging and computational modeling techniques. Their work shows that ants self-organize by interacting with the structures they build thanks to the addition of a pheromone to their building material.
FULL STORY

Three-dimensional simulations of ant nest construction.
Credit: © CRCA / CNRS (Toulouse)


Ants collectively build nests whose size can reach several thousand times that of individual ants and whose architecture is sometimes highly complex. However, their ability to coordinate several thousand individuals when building their nests remains a mystery. To understand the mechanisms involved in this process, researchers from CNRS, Université Toulouse III — Paul Sabatier and Université de Nantes[1] combined behavioral analysis, 3D imaging and computational modeling techniques. Their work shows that ants self-organize by interacting with the structures they build thanks to the addition of a pheromone to their building material. This chemical signal controls their building activity locally and determines the shape of the nest. Its breakdown over time and due to environmental conditions also enables the ants to adapt the shape of their nests. This work is published in PNAS on 18 January 2016.

The nest of black garden ants, Lasius niger, consists of an underground part made up of a network of galleries, and a mound of earth composed of a large number of bubble-shaped chambers closely interconnected with each other. Using 3D imaging techniques such as X-ray tomography[2] and a 3D scanner, the researchers characterized the 3D structures made by the ants as well as the construction dynamics. In addition, they analyzed the individual building behavior of the ants.

In the part located above ground, the insects pile up their building materials forming pillars that encircle the chambers. The ants preferentially deposit their soil pellets in areas where other clusters of pellets have already been created. They add a pheromone to their material, which stimulates the other ants to build on the same spot, leading to the formation of regularly spaced pillars. When the columns reach a height equal to the average body-length of an ant, the workers build caps on top of the pillars. They use their body size as a template to determine when they should stop building vertically and begin to deposit pellets laterally. The ants thus use two types of indirect interactions in order to build complex architectures.

In addition, the pheromone breaks down over time at a rate that depends on climate conditions, which enables construction to adapt to the environment. For instance, in a dry environment the amount of pheromone rapidly decreases and so fewer pillars are built. The chambers are therefore larger, which enables the ants to cluster there in order to preserve what little humidity there is. On the other hand, in a humid environment, the pheromone persists for a longer time, which leads to a greater number of pillars and to smaller chambers.

The researchers then developed a 3D mathematical model of nest construction, obtained by analyzing the individual behavior of the ants. The model shows that the two types of indirect interactions used by the ants to coordinate their activity faithfully reproduce the construction dynamics and the structures built during the experiments. It also highlights the key role played by the building pheromone in the growth dynamics and shapes of the nests.

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La cuarta parte de la biomasa de los animales terrestres de nuestro planeta son hormigas.

Esto significa que si pudiéramos sumar la masa de todos seres vivos terrestres del planeta y esta diera la cifra de 1000, 250 de esos mil serían hormigas.

Se calcula que el número de hormigas que habitan la tierra está entre 2.000 y 10.000 BILLONES.

Estas de la foto son al ganas de ellas, la verdad es que los número me producen admiración  ya que algo están haciendo bien desde hace mucho micho tiempo. No creéis?

Resultado de imagen para imagenes de hormigas

Ejemplares de Messor barbarus