Tag Archives: ants

What makes ant teeth so super strong and sharp

Credit: Pixabay.

It’s no secret that ants are exceptionally strong and fast relative to their body size. The average ant can carry up to 50 times its own body weight and can scurry away at a rate of nearly 800 times its body length a minute. However, it’s a lesser-known fact that ants also possess super strong teeth, which they use to chomp down on their picnic loot and burrow tunnels into the soil.

Now, scientists have zoomed in on the insects’ tiny dentures using atomic-scale imaging to learn more about what makes teeth so strong and sharp. In the process, the secret they revealed could be used to develop new miniature tools.

Teeth like a scalpel

Researchers at the University of Oregon and the U.S. Department of Energy’s (DOE’s) Pacific Northwest National Laboratory (PNNL) developed special techniques for measuring the hardness, elasticity, and mechanical resistance of objects at a miniature scale. The ant tooth, which is attached to an oversized mandible thinner than a strand of hair, marked the perfect occasion to test these techniques.

Materials scientist Arun Devaraj and doctoral intern Xiaoyue Wang, both from PNNL, focused an ion beam microscope on the tip of a tiny ant tooth. They used atom probe tomography to image the sample hit by the ions, allowing them to identify how individual atoms are arranged in the dental structure.

This investigation showed that the ant tooth is composed of individual atoms of zinc arranged in a specific, even pattern that ensures maximum cutting efficiency. What’s more, the structure also prevents the teeth from going dull, maintaining their sharpness throughout the insects’ lifetimes. And since the zinc atoms are distributed equally across the tooth, so is the biting force whenever the ant crunches on something relatively large, protecting its mandible.

“We could see that the zinc is uniformly distributed in the tooth, which was a surprise,” said Devaraj in a statement. “We were expecting the zinc to be clustered in nano-nodules.”

It makes sense that ants have evolved super-efficient teeth, considering they use their mandibles not only for chewing leaves and prey, but also for lifting, carrying, and defense.

According to calculations performed by Devaraj and colleagues, this structure allows the ants to use their energy much more effectively. The team estimates that, when biting, it uses only uses 60% of the force it would have needed if its teeth were made from the same materials as human teeth. This allows the ants to do more with fewer muscles. It’s likely that the same is true for other insects and crustaceans that employ similarly specialized dental tools.

Robert Schofield, associate professor at the University of Oregon and lead author of the study, believes there’s much to learn here. He has extensive experience studying steel microstructures to find the right mix of materials that enhances damage resistance, with a focus on corrosion resistance. Scofield believes biomimicking designs that take cues from the ant dentures by adding some evenly spread zinc in the material’s composition could prove useful in the future.

“The hardness of ant teeth, for example, increases from about the hardness of plastic to the hardness of aluminum when the zinc is added. While there are much harder engineering materials, they are often more brittle,” Schofield said.

Meanwhile, Devaraj and colleagues at PNNL are examining other tiny biological tools employed in the animal kingdom, from scorpion stingers to spider fangs.

The findings appeared in the journal Scientific Reports.

What makes ants remarkable diggers? It’s all about physics, study finds

If there’s one thing we know about ants, it’s that they are remarkable diggers, capable of building nests with multiple layers, connected by an intricate network of tunnels. Now, a group of researchers has used X-ray imaging to better understand the process through which ants build their tunnels. And the findings are just incredible.

Granular forces (black lines) at the same location in the soil before (left) and after (right) ant tunneling. Image credit: The researchers

Scientists have long been interested in ants, studying their collective behavior. While a few ants spaced well apart act like individuals, a pack of them close together behave more like a single unit – with solid and liquid properties. They are social insects, capable of organizing themselves in an efficient community to protect their colony. 

José Andrade, an engineer at the California Institute of Technology (Caltech), wanted to further explore tunneling ants after seeing examples of anthill art. These are pieces created by pouring molten metal, plaster, or cement into an ant mound, which flows through the tunnels. The soil is then removed to reveal the definitive structure.

“I saw a picture of one of these next to a person and I thought ‘My goodness, what a fantastic structure.’ And I got to wondering if ants ‘know’ how to dig,” Andrade said in a statement. “We didn’t interview any ants to ask if they know what they’re doing, but we did start with the hypothesis that they dig in a deliberate way.”

Andrade partnered with other colleagues at Caltech. They suspected that the ants poked around the soil, looking for loose grains to remove. Just like us when we play Jenga, taking off loose blocks and leaving the critical pieces. Those blocks are part of a “fore chain” that serves to jam the blocks together to create a stable structure.

A long process

The first step was to breed ants and learn how to work with them. But it was a very long first step that took over a year. There was a lot of trial and error in getting the ants to dig in small cups of soil that would later be loaded into an X-ray imager. This helped determine an optimal cup size and the ideal number of ants per cup. 

“They’re sort of capricious,” Andrade said. “They dig whenever they want to. We would put these ants in a container, and some would start digging right away, and they would make this amazing progress. But others, it would be hours and they wouldn’t dig at all. And some would dig for a while and then would stop and take a break.”

By x-raying the ants as they worked, the researchers were able to create 3-D animations showing their progress. Image credit: The researchers

Once they could finally set everything up, the researchers would take the cups and x-ray them, using a technique that created a 3-D scan of all the tunnels inside. This allowed them to create simulations and show the progress made by ants as they extended their tunnels farther below the surface – identifying a few patterns in their behavior. 

The ants tried to be as efficient as possible. They dug their tunnels along the inside of the cups, as the cup itself would act as part of their tunnels’ structures – meaning less work for them. They also dug the tunnels as straight and as steeply as possible, up to what’s known as the angle of repose. This is the steepest angle a granular material can be piled up before collapsing. 

The researchers also discovered something about the physics of the tunnels. As ants remove grains of soil, they are changing all the physical interactions of particles in and around the tunnel. Those chains rearrange themselves outside of the tunnel, strengthening the existing walls and relieving pressure from the grains at the end of the tunnel where the ants are working. 

But what about their initial hypothesis? Do ants actually know what they are doing? Apparently not. “They didn’t systematically look for soft spots in the sand. Rather, they evolved to dig according to the laws of physics,” Andrade said. Still, the researchers hope to keep studying this, but now with an artificial intelligence approach.

The study was published in the journal PNAS. 

The trap-jaw is the fastest in the world — and it independently evolved several times in ants

Trap-jaw ants are infamous for having one of the strongest bites among all animals, but we didn’t really understand how they evolved from more traditional jaws. A new study looking at their evolutionary history found that the distinctive mechanism behind trap-jaws has evolved independently several times across the globe.

Unlike normal gripping jaws, which open and close through the contraction of muscles, trap-jaws use a complex mechanism to latch themselves open and clamp down when needed. This mechanism allows the jaws to store energy much like a spring, and this can be released to produce a lot of force quickly.

Bit bite

“One of the central questions in biology is: how does something complex arise from something simple?” said Professor Economo, who leads the Biodiversity and Biocomplexity Unit at the Okinawa Institute of Science and Technology Graduate University (OIST).

“Structures like the trap-jaw depend on multiple interacting parts to function correctly. At first it can be hard to see how such complexity can arise through the gradual stepwise changes of evolution. Nevertheless, when we look closely biologists can uncover evolutionary pathways to complexity.”

A new study led by Professor Economo and Dr. Douglas Booher from Yale University tracked the evolutionary history of trap-jaws, finding that they evolved independently, on several occasions, around the globe. Many of the species that sport such jaws come from the Strumigenys genus, which includes over 900 species found in tropical and subtropical regions.

For the study, the team sequenced the genetic information of 470 species in this genus recovered from all around the globe, including two types of gripping jaws (ancestral and with modified trap-jaws). From this, they reconstructed their family tree, which shows how different species are related.

Finally, they analyzed the jaws and ants themselves using micro-CT scanners, allowing them to create 3D models.

One of the first observations the team made was that only minor changes in structure were required to turn a gripping jaw into a trap-jaw. They further report that after this transition took place, the heads of (now trap-jawed) ants also started to morph quite dramatically. Muscle restructuring and changes in the length and open-width of the jaws were among the key changes.

“Previously, we had thought that all trap-jaws had both divergent form and divergent function, so it was much less obvious as to whether the change in function could occur at the start or whether a lot of changes to the form were first needed as a precondition,” said Professor Economo.

“But it turned out there are many intermediate forms out there of the trap-jaw mechanism that people just hadn’t identified before, some which differ only slightly from the ancestral form.”

In a collaboration with the lab of Andrew Suarez at the University of Illinois, the team also used high-speed video cameras to capture the jaws of Strumigenys ants in motion. They were thus able to determine that the trap-jaws have the fastest yet “acceleration of any animal body part that can return to its original position”. Such jaws were seen to accelerate a hundred times faster than standard mandibles, closing a thousand times faster than a human eye can blink. Which sounds impressively fast.

But they need all the speed they can get. Strumigenys ants use their jaws to capture springtails, their preferred prey, which employ a spring-loaded escape mechanism (hence the name). There’s still a lot we don’t understand about their hunting habits, but we do know that ants with shorter trap-jaws tend to be passive hunters, hiding in leaf litter with open jaws, waiting to bite down on any prey passing by. Longer-jawed ants, meanwhile, actively look for prey to bite into.

Both types of ants can be found in every region across the globe, the authors add. They believe that differences in behavior can explain why there are so many different shapes of trap-jaws out there. However, what is yet unclear is whether the genetic background that supported the change from normal- to trap-jaws is the same for all species, or whether they all reached the same solution through different genetic changes.

“It was really striking how we saw the same variations evolve again and again on different continents. It illustrates how repeatable evolution can be, finding similar solutions to life’s challenges,” said Professor Economo.

Going forward, the team plans to sequence the genomes of representative Strumigenys species across the world in order to determine this.

The paper “Functional innovation promotes diversification of form in the evolution of an ultrafast trap-jaw mechanism in ants” has been published in the journal PLOS Biology.

Scientists discover the first insects with a shell-like armor

r. a Ac. echinatior ant with a whitish cuticular coating
(Photo T.R.S.). b SEM image of ant cuticle with crystalline coating. Credit: Nature Communications.

Calcareous biominerals have been incorporated by many animals across evolutionary history, particularly by crustaceans with their signature shells. Somewhat surprisingly, this kind of protection has never been seen before in insects, which belong to the same group as crustaceans — both are arthropod classes. But scientists have now found the first evidence of high-magnesium calcite in the armor overlaying the exoskeletons of leaf-cutter ants (Acromyrmex echinatior).

Armored bacteria farmer

For a number of years, Cameron Currie, a University of Wisconsin–Madison professor of bacteriology, has been studying Streptomyces bacteria. Currie and colleagues showed that these microbes provide leaf-cutter ants with protection against infections, which suggests that both the ants and their microbiome could become a new source of antibiotics. Bearing in mind the frightening rise of antibiotic-resistant bacteria, this research is extremely important, perhaps even crucial.

While they were studying leaf-cutter ants in an effort to identify what the insects might give in return for the protection they receive, Hongjie Li, a postdoctoral scientist at Currie’s lab, discovered crystals on the surface of the exoskeletons. On closer inspection, it turned out that the crystals were biominerals — the very first to be encountered in the insect world.

On the morning that Li performed the X-ray scans of the ants, he couldn’t believe his eyes.

“I texted Cameron right away by saying ‘I found a rock ant’. I still can feel the joyful moment right now,” Li, who is the first author of the new study published in Nature Communications, told ZME Science.

Subsequent live-rearing and in vitro synthesis experiments showed that the magnesium-rich calcite armor develops as the ants mature, thereby increasing the hardness of their exoskeletons.

The high magnesium content of the armor is particularly exciting, Currie told me, because it is very rare in the biosphere. “So, our ants have really unique and strong armour,” the researcher added.

Atta cephalotes soldier, the largest worker caste within the leaf-cutter ant colonies, extending her mandibles over an Acromyrmex echinatior worker. Acromyrmex echinatior major workers have a layer of high-magnesium calcite that acts as armour, protecting them from rival ant species attacks. Credit: Caitlin M. Carlson.

Worker ants with biomineralized exoskeletons were more likely to survive encounters with Atta cephalotes soldier ants, according to observations performed by the researchers. What’s more, the armor also offered protection against infection from the disease-causing fungus Metarhizium anisopliae.

Apparently, there are quite a few reasons why such an armor must have been favored by natural selection. But intriguingly, the researchers liken the ants’ bacterial farming to human agriculture.

“Leaf-cutter ants evolved around 20 million years ago and are ecologically dominant in the new world tropics. Their success parallels the important role agriculture plays in the rise of human dominance over the planet over the last 10,000 years. There are other parallels between these ant and human agriculturalists. Like crop pathogens causing pestilence over human agricultural history, the ant crops are highly susceptible to specialized pathogens that have evolved to exploit them. Just as humans rely on chemicals to defend our crops, the ants have evolved the use of bacteria to derive antibiotics to control crop infection,” Currie told ZME Science.

“Our finding of biomineral armor in a leaf-cutting ant provides another exciting new parallel to humans: the evolution of protective armor for engaging in wars with other agriculturalists,” he added.

There may be more insects with biomineral armor. One of the reasons why they’re not common is because most insects already have a hard, sturdy exoskeleton, which generally offers sufficient protection. In the future, Currie and colleagues would like to study in more detail how the biomineral forms, as well as the evolutionary origins of the armor across the ants that grow fungus gardens. 

How ants grew super-strong muscles after losing their wings

Ants’ relative strength-to-size ratio is among the highest in the world, making them some of the most resilient creatures out there. For instance, the neck joint of the common American field ant can withstand pressures up to 5,000 times the insect’s weight.

This phenomenal strength is owed to ant’s mechanical configuration — but it wasn’t always like this.

Millions of years ago, the ancestors of ants had wings. A new study highlights how this transition to a wingless life enabled worker ants to become some of the most successful insects in the animal kingdom.

Losing flight to make way for super muscles

Worker ants and queens (with wings). Credit: Philip Gronski.

Most science about ants tends to focus on their social behavior, which is also remarkable. But unlike this majority of studies, researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) in Japan and the Sorbonne University in Paris focused on ant body mechanics. They wanted to see how the loss of flight in worker ants impacted the evolution of their strength.

Only reproductive ants have wings, which are able to fly only during the breeding season. But the foraging worker ants of any species that you see trailing on the sidewalk or in your kitchen will never have wings.

The project was started by Dr. Christian Peeters, an ant biologist at the French National Scientific Research Agency (CNRS). Along along with colleagues, he used advanced X-ray imaging technology to scan the internal and external anatomy of individual worker ants. Particularly, the focus was on the thorax, which perfectly organizes the worker ants muscles for maximum strength.

Sadly, Peeters passed away this year before he could see this study published.

“My colleague, Christian Peeters, had been thinking about the importance of the winglessness of ant workers as a key evolutionary change, and since my lab had been studying ant anatomy with x-ray micro-CT, he proposed we investigate how the loss of flight changed the thorax,” Evan Economo, who leads OIST’s Biodiversity and Biocomplexity Unit, told ZME Science.

“Organisms that fly have massive constraints on their anatomy and physiology. The key finding from this study is that losing flight freed up the ant thorax to be redesigned for ground labor, and we identified five key changes that we observe in these wingless workers.”

Flying is an extraordinary ability — but it comes at a very high cost. In flying insects, the wings often occupy more than 50% of the thorax, which squeezes other muscles involved in supporting other body parts, such as the head, legs, and abdomen.

After worker ants lost their wings, all that extra space allowed the remaining muscles to expand and reorganize. For instance, the authors of the new study found that three muscle groups expanded in volume in the thorax.

The neck muscles were also modified, as well as the internal attachment of the muscles.

“The thorax of winged insects is dominated by muscles that power flight.  Without these, space is freed up for the expansion and reorientation of muscles that move support the head, bear and transfer load to the legs, and move the abdomen,” Economo said.

This reconfiguration wasn’t necessarily straightforward, though. When looking at wingless wasps, the researchers found that they adapted to the loss of flight in a completely different way. Unlike the perfectly ordered ant colonies, wingless wasps are solitary creatures that forage for food as they find it. So, the wasps were far less pressured by evolution to evolve strong muscles to carry food back to their queen and young nestmates.

Next, the researchers would like to study other muscle groups as closely as the thorax, such as the mandible and legs.

“Everyone knows ants are strong and efficient workers.  We hope this study helps people understand a little bit about why. We will continue our work to uncover the evolutionary story of how ants evolved and how they became such a big part of our world.  We have studies ongoing about their head anatomy, brains, mandibles, legs, etc,” Economo told ZME Science.

The findings appeared in the journal Frontiers in Zoology.

Ants quickly adapt to danger, build sand structures to access food and avoid drowning

Researchers have observed black imported fire ants using sand to draw liquid food out of containers. Credit: Dr. Aiming Zhou and Dr. Jian Chen.

Black imported fire ants (Solenopsis richteri), or simply BIFA, have a water-repelling cuticle that allows them to float on the water’s surface. So, typically these ants face minimal risks of drowning when crossing shallow waters or foraging for food in liquid solutions.

But when researchers changed a liquid’s surface tension such that the BIFAs would stop floating, the ants were quick to adapt. Aware of the danger, the ants congregated and used nearby grains of sand to build structures that not only saved them from drowning but also enabled them to draw liquid sugar out of the containers.

The study was led by Dr. Aiming Zhou, an associate professor at Huazhong Agricultural University in Wuhan, China, in collaboration with researchers from the US, including Dr. Jian Chen, Research Entomologist at The U.S. Department of Agriculture’s (USDA) Agricultural Research Service (ARS) in Stoneville, Mississippi.

“We found that when the drowning risk of ants was elevated by adding surfactant into the sugar water, instead of foraging directly over the container, black imported fire ants changed their foraging strategy to build a sand structure that can function as a syphon. The structure quickly syphoned the sugar water out of the container, so ants can collect the liquid food outside the container. This syphon structure not only prevented ants from being drowned, but also facilitated the collection of the sugar water, likely by providing larger operational space,” Chen told ZME Science.

Danger sharpens the mind

Chen and colleagues at the USDA have been studying fire ants for many years. These insects, which have a venomous sting, are one of the most important pest ants in the United States, so the researchers were focused on developing bait products for controlling them.

While working with water-based bait products, Chen added surfactants in order to incorporate a water-insoluble active ingredient. But the ants’ reaction and extraordinary adaptive prowess stunned the scientists.

This is the first time this sophisticated tool use has been reported in animals.

In lab experiments, the researchers noticed that the BIFAs started depositing sand grains on the inside of a container filled with sugar water mixed with the surfactant. This exceptional tool-making ability allowed the ants to draw sugar out of the container while providing a footing so they won’t drown.

That’s quite extraordinary, something that Chen was quick to notice from the beginning.

“Although this discovery came about when we were looking for something else, we wouldn’t consider it as the result of a true accident. It took a prepared mind to follow through and turn a routine observation into an unexpected discovery,” he told me in an email.

The sand structures were never observed when the ants foraged in safe containers filled with only pure sugar water. It was only when they recognized they were endangered that they quickly adapted and showed how resourceful they could be, adjusting their tool use to rise up to the challenge.

“We do not know how ants coordinate this behavior. We hope our paper will motivate others to do the related investigations,” Chen said. In any case, tool use is widely regarded as a sophisticated cognitive ability, which is mostly associated with primates and some species of birds.

Few examples of tool use have been documented among invertebrates. This study, which appeared in the journal Functional Ecology, shows that we’re only beginning to scratch the surface of what is possible and that intelligent behavior can surface in all kinds of unsuspecting scenarios.

“The next steps will be to determine how widespread this behavior is in other ant species.  This study demonstrates that ants can not only recognize the increase in foraging risks, but also make corresponding adjustments to their strategy by using and building tools.  The manufacture of a syphon structure to acquire liquid food has never been reported in the animal kingdom. Ants may be “smarter” than we expected,” Chen concluded.

Plants evolved to manipulate ants into defending them

Plants may be more dynamic thank you think — a new study found that plants evolved alongside ants, persuading the insects to protect and take care of them.

Arboreal ants that have evolved closely with the trees they live in. Image credits: Field Museum / Corrie Moreau.

If you were to look at the interaction between ants and some plants, you’d think it’s a one-way street. Plants offer shelter and succulent nutrients, while ants just come and reap the rewards. But that couldn’t be further from the truth — a new study analyzed the genome of plants and ants that share the same ecosystem, finding that plants have quite a few tricks up their sleeve.

Essentially, plants evolved around the ants, developing ways to trick the insects into protecting them and spreading their seeds.

“My main interest is in studying how interactions between organisms have evolved, and how these interactions shape their evolutionary history. When did ants start using plants, and when did plants start making structures for ants to use?” says Matt Nelsen, a Field Museum post-doctoral researcher and the lead author of the PNAS study.

The structures Nelsen is referring to are hollow spikes that some plants developed. Ants use these spikes as shelter and protection against other insects and even mammals. Yet while they’re protecting themselves, the ants also protect the plant. Similarly, other plants have started producing juicy nectar that the ants like to eat — so much that they will protect the plant from unwanted intruders. Some ants are freeloaders, eating the nectar and running away, but most of the time, ants protect the plant. In a way, the plant pays a protection tax for the ants to act as its bodyguards.

A plant that evolved hollow thorns for ants to shelter in. In exchange, the ants defend the plant from attacks from other insects and mammals. Image credits: Field Museum / Corrie Moreau.

Another creative mechanism developed by some ants relies on using the ants to spread its seeds. Plants get ants to help them move their seeds around, by bribing them with rich food packets attached to seeds called elaiosomes.

“The ant will pick up the seed and carry it away, eat the food packet, and discard the seed – often in a nutrient-rich area where it’ll grow better, and since it’s farther away from its parent, they won’t have to compete for resources,” Nelson explains.

The research team looked at traits such as these, mapping the genetic history of ant-friendly traits for plants, as well as the ants’ plant usage. It seems that plants may be in the driver’s seat since plants didn’t evolve these specialized structures until long after ants had been relying on them for food and habitat.

“Some ants don’t directly use plants for much, while others rely on them for food, foraging habitat, and nesting. We found that to become fully invested in plant-use, ants first began foraging arboreally, then incorporated plants into their diet, and then from there, they started nesting arboreally. While this stepwise shift towards an increased reliance on plants is intuitive, it still surprised us,” says Nelsen.

The next question would follow in a chicken-and-egg fashion: what came first, the ants that took advantage of the plants, or the plants that set things up for the ants? The history of ants and plants evolving together goes back to the Mesozoic when dinosaurs ruled the Earth, and it’s not easy to tell from fossils how the organisms interacted.

“There are very few fossil records of these structures in plants, and they don’t extend very far back in time. And there are tons of ant fossils, but they typically don’t show these ant behaviors–we don’t necessarily see an ant preserved in amber carrying a seed,” says Nelsen.

However, using DNA data and ecological databases, researchers mapped the history of a plant’s ant-friendly traits and of ants’ plant use, finding that plants seem to have made the first step in this partnership. In other words, it appears that plants initiated the collaboration, and they have more to gain from it — particularly since ants that eat, forage on or nest in plants don’t seem to be better off than those who don’t.

“We don’t see parts of the ant family tree that includes ants relying on plants for food or habitat diversifying or growing any faster than those parts of the tree that lack these interactions,” says Nelsen. “This study matters because it provides a glimpse into how these widespread and complex interactions evolved.”

The study has been published in the Proceedings of the National Academy of Sciences,

Ant Close Up.

Farmer ants unknowingly domesticated their fungi crops by sequestering them in dry environments

Farmer ants have mastered agriculture long before humans — in fact, some species have been practicing almost industrial-scale agriculture on domesticated crops for millions of years now. Scientists at the Smithsonian’s National Museum of Natural History are now trying to determine exactly when and where that started.

Ant Close Up.

Ants are pretty cool. They also have the distinction of being the planet’s oldest farmers, seeing as they have a few millions of years ahead of us on the whole thing. Safely ensconced in underground shelters, these insects have been working and munching on various types of fungi the whole time. But some time in their agricultural development path, one group of ants got even better at farming by completely domesticating their crops.

This allowed them to tailor the crop to their needs, achieving a level of complexity that rivals our agricultural practices today. We know this group as higher agriculture ants, while their counterparts that toil away on wild or half-wild crops are called lower agriculture ants. To find out when and why the transition from lower to higher agriculture took place, researchers from the Smithsonian National Museum have traced the genetic heritage of farming and non-farming ants from wet and dry habitats throughout the Neotropics.

The high agriculture ant

Ants and the fungi they grow share an almost symbiotic relationship. When a queen’s daughter leaves the nest to establish a colony, for example, she takes a piece of fungi to start the new crop. For lower agriculture ants, however, this bond isn’t quite as tight. Such species live primarily in wet rainforests, where the fungi can escape the colony and settle in the wild. If the crops falter, the ants will sometimes go fetch fungi back to the colony — so it’s not all bad that both species are less dependent upon the other.

But this more casual fling means the fungi used for the crops is at best a mix of cultivated and wild heritage, limiting the ants’ ability to domesticate it.

 

And as we’ve found out throughout time, you absolutely, definitely, hands-down want to domesticate your crops. It makes food look better, taste better, more nutritious, and most importantly, more plentiful. One side effect of domestication, however, is that the crops lose most of their ability to survive without farmers, since they’re so well adapted to being tasty, guarded, and tended to, that they’re bad at everything else.

That’s also the case with higher agriculture ants. Their crops are completely dependent on the ant farmers and have never been found living without them. Higher agricultural ants’ food grows faster and is more nutritious, so they can live in bigger communities and pool all resources towards growing the fungus, removing pathogens, hauling waste, and keeping environmental conditions just right for the crops.

“These higher agricultural-ant societies have been practicing sustainable, industrial-scale agriculture for millions of years,” said Schultz. “Studying their dynamics and how their relationships with their fungal partners have evolved may offer important lessons to inform our own challenges with our agricultural practices.”

“Ants have established a form of agriculture that provides all the nourishment needed for their societies using a single crop that is resistant to disease, pests and droughts at a scale and level of efficiency that rivals human agriculture.”

Today, however, many species of agricultural ants are threatened by habitat loss. Schultz has been collecting specimens from various species to preserve in the museum’s cryogenic biorepository for future genomic studies in case these ants go extinct. For this study, he and his colleagues have compared the genes of 119 modern ant species, most of which were collected over decades of Schultz’s work in the field. The DNA sequences were compared at over 1,500 genome sites of 78 fungus-farmer and 41 non-fungus-farming ant species.

Divide and domesticate

Ted Schultz and co-author Jeffrey Sosa-Calvo excavate a lower fungus-farming ant nest in the seasonally dry Brazilian Cerrado, 2009.
Image credits Cauê Lopes and Ted Schultz / Smithsonian.

They identified the closest living non-farming relative of today’s fungus-farming ants based on their analysis, then looked at the geographic range of these species to try and deduce under what conditions higher agriculture emerged. In other words, when the crops became dependent on the ants for survival. According to the evolutionary tree they constructed based on the genetic analysis, the team believes ants first transitioned to higher agriculture in a dry or seasonally dry climate, somewhere around 30 million years ago.

Mean temperatures on Earth were dropping at the time, so dry areas were becoming more prevalent. As more and more ants lost their initial habitat and moved to these areas, they brought their crops along. But the fungi evolved to live in forests and couldn’t do the old leave-the-nest trick without dying here. In fact, they couldn’t do the old don’t-die trick at all without the ants in the new environment.

 

“But if your ant farmer evolves to be better at living in a dry habitat, and it brings you along and it sees to all your needs, then you’re going to be doing okay,” Schultz explains.

“If things are getting a little too dry, the ants go out and get water and they add it. If they’re too wet, they do the opposite.”

So the fungi became completely dependent on the ants since they couldn’t escape and return to the wild. Being carried over into a hostile habitat, the fungi’s survival depended on the survival of the colony and it found itself “bound in a relationship with those ants” what wasn’t there in wet forests, Shultz adds.

 

The shift shows how a species can become domesticated even without its farmers consciously selecting for certain traits, as human farmers would do. By moving into the drier habitats, the ants isolated their crops and decoupled their evolution from its relatives — making it take on new traits that it wouldn’t need in the wild.

The full paper “Dry habitats were crucibles of domestication in the evolution of agriculture in ants” has been published in the journal Proceedings of the Royal Society B: Biological Sciences.

Credit: Pexels.

Ants plot the position of the sun and memorize their surroundings to navigate

Credit: Pexels.

Credit: Pexels.

Ants are great navigators but what scientists discovered recently left everyone dumbstruck. According to researchers from University of Edinburgh, UK, and CNRS in Paris, the insects can keep a straight path by plotting the Sun’s position in the sky against their visual surroundings. That’s sort of like trying to find your way home while walking backwards.

“Our main finding is that ants can decouple their direction of travel from their body orientation,” said Dr Antoine Wystrach of the University of Edinburgh. “They can maintain a direction of travel, let’s say north, independently of their current body orientation.”

Despite their puny size, ants are actually big-brained. They have the animal kingdom’s biggest brains, relative to their bodies. Brains account for up to 15% of an ant’s total mass in some species while humans’ weigh in at a meager 2%. This at least partially explains ants’ knack for finding their way home under almost any condition from foraging trips.

Scientists previously knew ants can calculate distances and direction based on pheromones and the sun’s position, but the sophistication escaped them.

The UK and French researchers studied desert ants (Cataglyphis velox). First, the ants were let to familiarize themselves with a route that included a 90° turn. Ants that were given a tiny cookie crumb to carry traveled on this path without difficulties. Ants loaded with larger crumbs, however, had to move backward to support the weight, and unlike the others, they maintained their bearing instead of turning.

There’s also more to it. The ants loaded with the hefty crumbs would occasionally drop their food and turned around to observe the scenery, all while their bodies were pointed in the right direction. They would then return to the crumb and resume towing it backward. This behavior suggests that body alignment seems important for navigation. The findings also suggest ants can memorize a path after visualizing it and recall the existence of a dropped crumb, as well as its location. Three kinds of memory are working in tandem: visual memory of the route, memory of the new direction to follow, and memory of the crumb to retrieve. Not bad for an animal with a smaller than a pinhead.

An experiment that used mirrors to obscure the sun caused the ants to set off in the wrong direction. This proves the ants used celestial cues to maintain their bearing while walking backward. Furthermore, ants were able to move in straight paths, whether walking forward, backward, or sideways.

The findings published in Current Biology could be used to design novel computer algorithms that guide robots. Most importantly, they show that the world of ants is far more complex than previously thought.

 

 

Most ants don’t do much, and that makes the colony more efficient

Ant colonies increase their efficiency by letting workers take time off. New research shows that as the hive becomes more numerous, as many as 80% of workers could be doing nothing at a time.

Image credits Unsplash / Pexels.

We need a nice work-rest balance — although exactly what this ratio is varies wildly from person to person. Up to now, we’ve thought that we get the benefit of rest because we’re smart, while simpler beings such as ants slave away and then they die. We’ve got that one wrong, researchers at the Missouri University of Science and Technology say.

Ant colonies, they showed, can only function because a certain percentage of workers rest at any time.

“It has been a long-standing question in the field as to why large colonies of ants use less per-capita energy than small colonies,” says Dr. Chen Hou, assistant professor of biological sciences at Missouri S&T and lead researcher of the paper. “In this work, we found that this is because in large colonies, there are relatively more ‘lazy workers,’ who don’t move around, and therefore don’t consume energy.”

“We found that the portion of inactive members of a group increases in a regular pattern with the group size,” Hou says.

The team put together specialized computer-imaging software to look at an ant colony and track the motion trajectories of each individual. Previously, similar research only followed the ants for a few minutes. But the team’s algorithm allowed them to follow the movement of ants over large periods of time with better accuracy than anyone before them.

This way, they found that most of the colony ‘sleeps’ to conserve energy. On average, around 60% of workers in a 30-ant group were not moving about. This ratio jumped up to 80% for a 300-strong group of ants.

Rest harder, comrade

So what’s with the vacay? Well, they do it for the common good.

The colony becomes more efficient in the long term by keeping some of its workers on stand-by. While an all-hands-on-deck approach would maximize the speed of resource acquisition, it also requires huge energy expenditure (feeding the ants) and increases foraging time (as nearby resources are over-exploited and workers need to walk to more distant sources). The team explains that off-duty ants help conserve food, energy, and other resources — while the colony gains resources at a slower rate, forage time is reduced and energy expenditure is hugely reduced.

“The simultaneous energetic measurements showed that the per capita energy consumption in the 300-ant group is only 50 percent of that in the 30-ant group,” Hou says.

“We found that walking ants consume five times more energy than resting ants,” he added. “This means that energy wise, one walking ant is equivalent to five resting ants. Thus, if a group has 20 percent active members, this group would consume 180 percent more energy than a similar sized group with all inactive members.”

So the ants try to hit a balance between the need for new resources, and the need to conserve those already harvested. The ‘lazy’ ants are still an asset to the colony. Ants rest by rotation, so there’s always a pool of fresh workers to replace the ones on duty. They can also be called upon in an emergency, kind of like a reserve army or repair team.

“We postulate that ant colonies balance these two optimization rules [income and expenditure] by the coordination of the forager’s interaction.”

“It is intuitive that colonies have inactive members […] But it is unclear why the proportion of the inactive members is not a constant — why larger colonies have relatively more ‘lazy’ workers,” Hou concludes.

Observing how ants maximize efficiency by balancing some work with a lot of rest could help make our society more productive and sustainable.

Fingers crossed on that one.

The full paper “Heterogeneous activity causes a nonlinear increase in the group energy use of ant workers isolated from queen and brood,” has been published in the journal Insect Science.

Ants craft tiny sponges to make it easier to carry food

“Ants are smarter than we give them credit for” is something we seem to write a lot – and yet it happened again.

Ants love their sweet liquids! Image credits: J. Coelho.

Tool use is something we consider reserved for intelligent species. It used to be that only humans were considered advanced enough to craft and use tools – but now we know better. Several species of apes and monkeys craft and use tools, even learning how to use them from humans. Elephants do it, as do some otters and of course, dolphins. Even some birds (most notably crows and ravens) have been observed using tools. It seems like several species of animals are much smarter than we gave them credit for – and ants are no exception.

István Maák, a researcher at the University of Szeged in Hungary, offered two species of funnel ants (Subterranea and Senilis)  liquids containing water and honey. Alongside, he gave them several tools that might help them carry food easier.

Firstly, the ants started experimenting. They were testing to see which tool was most effective. In the end, they settled for pieces of sponge or paper, which could absorb the honey better, making it easier to carry back home. The Subterranea workers (of the first species) used small soil grains to transfer diluted honey and sponge to transport undiluted honey. Many of them even tore the sponge into smaller bits, so they could better handle it. Meanwhile, Senilis first used all tools, and in time focused more and more on pieces of paper and sponge, which they used to soak up the honey.

There were previous indications of ants using tools, such as mud or sand grains, to collect and transport liquid to their nests, but this is special because the ants experimented with the materials not commonly found in their environment. Because they treated honey and diluted honey differently, this suggests that even without any previous experience with the materials, they accounted for the properties of both the tool and the material they were transporting. Also, they learned as they went and did so very fast. Valerie S. Banschbach at Roanoke College, Virginia, believes this is a testament to their mental proficiency – even if they have big brains.

“Many other accomplishments of these small-brained creatures rival those of humans or even surpass them, such as farming fungi species or using ‘dead reckoning’, a sophisticated navigation to find their way back to the nest,” Banschbach told NewScientist. “The size of brain needed for specific cognitive tasks is not clear.”

It’s likely that funnel ants developed this strategy and became better at tool handling because unlike many other ant species, they can’t expand their stomach, so they needed to find a better way of transporting things.

Journal Reference: István Maáka, Gábor Lőrinczi, Pauline Le Quinquis, Gábor Módraa, Dalila Bovet, Josep Call, Patrizia d’Ettorre. Tool selection during foraging in two species of funnel ants. http://dx.doi.org/10.1016/j.anbehav.2016.11.005

Philidris nagasau and a young specimen of its Squamellaria host, Credit: G. Chomicki, LMU

Fiji ants were the first plant farmers some three million years ago

You won’t find people who take greater pride in their work than farmers. Maybe for good reasons, too, considering that their sweat and blood keeps us all fed. The advent of every human civilization is tied up with agriculture. That’s the very least a race needs to master before it can move to something bigger, like writing poetry or landing spaceship or playing golf. It took our human ancestors a while before they realized the same plants they were foraging could be coaxed to sprout where they desired, at a predictable rate. That happened only some 13,000 years ago. Ants, on the other hand, have been doing it for millions of years.

World’s first farmers

Philidris nagasau and a young specimen of its Squamellaria host, Credit: G. Chomicki, LMU

Philidris nagasau and a young specimen of its Squamellaria host, Credit: G. Chomicki, LMU

Since the Pliocene Epoch, about three million years ago, an ant species native to the Fiji islands called Philidris nagasau has been farming and harvesting Squamellaria plants. These ant-favored crops look more like lichen than plants, growing inside the crevices of trees. But don’t let appearances fool you. These are still plants and the ants take all the precautions and with all the diligence a human farmer would entrust to see their crops blossom.

The ants live inside the plant’s hollow structures, the domatia, and Guillaume Chomicki, a botanist at the Ludwig-Maximilians-University of Munich, followed their lives for a couple of months. This is how he and colleagues eventually found that the ants actively and purposely gather the Squamellaria seeds and place them at strategic locations. They then fertilize the seeds with their poop. Once the plants grow, the fruits are harvested and distributed among the colony, while the seeds are yet again collected to restart the process.

Because the crops double as a nest, a colony can cover several Squamellaria plants.

“One often finds dozens of colonies, connected by ant highways, on a single tree. All of these individuals are the progeny of a single queen, whose nest is located in the center of the system,” Chomicki explains.

While Fiji’s Philidris nagasau ant look like the world’s first plant farmers, they’re certainly not the first farmers. That distinction belongs to other ants, the famous leaf-cutter ants whose ancestors have been farming fungus since at least eight million. A recent Smithsonian paper which studied the genomes of various species of attine ants as well as the fungus that they cultivate found farming could be as old as 65 million years. Other species of ants have their own livestock, herding aphids by chemically subduing them. The ants then ‘milk’ the aphids for their sugar-rich secretions.

The relation between Squamellaria and Philidris nagasau is far more specialized than anything seen in another species that practice farming. Besides being the first ant species that farms plants, their relationship is highly dependent on one another. The plants can’t draw nutrients from the soil, so they rely on the ants for fertilization. The ants, in turn, can not survive without the fruit and shelter of the plants.

 

 

Farmer ants still struggle with undomesticated crops, study finds

A new Panama Smithsonian Tropical Research Institute (STRI) finds that modern relatives of the first fungus-farming ants still haven’t domesticated their crops. The study draws a strong parallel between the difficulties these ants faced and early human farmers faced.

Image via pixadus.

Some time after the dinosaurs went extinct 60 million years ago, the ancestors of leaf-cutter ants decided it was time to settle down. Just like us, they traded hunting and gathering for a more secure source of food — agriculture. You can still see their legacy snaking in busy lines through the rainforest carrying bits and pieces of plants over their heads. All this material underpins a huge, almost industrial agricultural complex. But for all their hard work, the ants’ harvest is limited by a farmer’s worst nightmare — a wild crop.

A new study at the Smithsonian Tropical Research Institute (STRI) in Panama revealed that living relatives of the earliest fungus-farming ants still have not domesticated their crop, a challenge also faced by early human farmers.

Modern leaf-cutter ants and the fungus they grow can’t survive without each other. The fungus is so important to the ants that young queens take a bit of it from the home nest and the colony they establish revolves around the farms they set up from this tiny bit. The fungus, in turn, doesn’t have to waste energy producing spores to reproduce itself. But what if the fungus…wants to make spores?

“For this sort of tight mutual relationship to develop, the interests of the ants and the fungi have to be completely aligned, like when business partners agree on all the terms in a contract,” said Bill Wcislo, deputy director at the STRI and co-author of the new publication in the Proceedings of the National Academy of Sciences.

“We found that the selfish interests of more primitive ancestors of leaf-cutting ants are still not in line with the selfish interests of their fungal partner, so complete domestication hasn’t really happened yet.”

Humans harvest vegetables before they go to seed — at this stage, the plants start diverting most of their energy and nutrients towards producing seeds, thus limiting their value as foodstuffs. And just like us, ants want to make sure that the fungus puts as little energy as possible into growing spores so it will grow bigger and fatter. What ants want is for the fungus to grow hyphae, the thread-like protrusions which they can eat. But the crop has its own plan so the ants carefully starve it into doing what they want.

Marie Curie Post-Doctoral Fellow of Jacobus Boomsma’s lab at the University of Copenhagen Jonathan Shik and his team found in an STRI study of Mycocepurus smithii — an ancestor of the leaf cutters that has not yet domesticated its fungal crop — that the ants alter what they feed the fungus to limit its spore production. The ants carefully manage the protein and carbohydrate content of the fertilizer they use to control how many mushrooms their cultivars produce. When they fed it mulches rich in carbohydrates, the fungus can produce both hyphae and mushrooms. But carefully rationing the amount of protein it receives can prevent the fungi from making mushrooms.

The downside of this is that by starving their crops, the ants severely limit the output of their fungal cultivars.

“The parallels between ant fungus farming and human agriculture are uncanny,” Shik said. “Human agriculture evolved in the past 10,000 years.”

“It took 30 million years of natural selection until the higher attine ants fully domesticated one of their fungal symbiont lineages. We think that finally resolved this farmer-crop conflict and removed constraints on increased productivity, producing the modern leaf-cutter ants 15 million years ago,” Boomsma said.

“In contrast, it took human farmers relatively little time to domesticate fruit crops and to select for seedless grapes, bananas and oranges.”

The full paper titled “Nutrition mediates the expression of cultivar–farmer conflict in a fungus-growing ant” has been published in the journal PNAS.

Pheidole viserion, a newly discovered ant species from Papua New Guinea © OIST

Meet Viserion and Drogon: the new ant species named after the Game of Thrones dragons

Pheidole viserion, a newly discovered ant species from Papua New Guinea © OIST

Pheidole viserion, a newly discovered ant species from Papua New Guinea © OIST

The island of New Guinea is home to some of the rarest animals on the planet. Among them are over 800 species of ants with a diverse range of fascinating characteristics, each well-suited to their unique island habitat. Scientists estimate that around 60% of these ants are found only in New Guinea. In many cases, a single species originally colonised the island and then developed into multiple distinct forms.

Now two new species of ant have been discovered with the help of a major technique that uses 3D imaging technology to identify insects. The ants themselves have a particularly striking appearance thanks to their formidable spine-covered exoskeletons.

Perhaps just as notable as their appearances, though, are their names, Pheidole viserion and Pheidole drogon, inspired by the fire-breathing dragons from the fantasy series Game of Thrones. While not quite in the same size bracket as their mythical namesakes, the ants do have a strong resemblance to the dragons thanks to the distinct blade-like serrations adorning their backs.

Unlike the dragons of fantasy, however, these ants are a product of evolution. So what is the point of their ornate spines? The answer can be found by looking at the social structure of their colonies. The Pheidole group of ants comprises over 40 species that are widely distributed across the island’s rainforests.

Pheidole ants also have several different types or “castes” of worker, each physically specialised for performing specific tasks within the colony. There are smaller “minor” workers and larger “major” workers, commonly referred to as soldiers due to their role in defending the colony from predators and rival ants.

Not fire-breathing, but still pretty scary. Fischer et al

The spines could be seen as a defence mechanism for the soldiers, but this may not be the full story. Soldiers are often many times the size of minor workers and have disproportionately large heads that are packed with muscle, making them formidable adversaries. Their heads are so large, in fact, that they require special skeletomuscular adaptations just to support their extra weight. Results from a kind of imaging technique known as “X-Ray microtomography” have suggested that the ants’ spines are in fact a by-product of this muscular support system, rather than a kind of armour.

This novel imaging method is more like something from science fiction than fantasy, and is opening up the possibility that new insect species could be identified and catalogued much more easily than before. The process works by scanning a mounted specimen with X-rays while rotating it 360 degrees. This produces a 3D cross-section that can then be used to make a virtual model.

Time-saving technique

In this way, X-Ray microtomography allows scientists to capture precise 3D renditions of their specimens and then easily share them with colleagues around the world. This means insects can be compared and identified without the need to send physical samples back to a lab, saving time and reducing the risk of damaging them. Even more impressively, the technique also maps the internal structures of the insects so they don’t need to be dissected for scientists to understand their physiology.

In fact, X-Ray microtomography has the potential to eliminate the laborious tasks of labelling, fixing and dissecting insect specimens that are currently commonplace in science, replacing them with a simple and rapid exchange of data files. In this case, the process also enabled the researchers to uncover new information about the anatomical structure of the Pheidole ant spines, giving them further insight into their biological function.

Classifying plants and animals is still an important tool for studying and monitoring biodiversity. New Guinea in particular holds rich potential for the discovery of new and charismatic species, as the discovery of P. viserion and P. drogon demonstrates. The island comprises just 1% of the world’s land area but is estimated to harbour 5% of all plant and animal species, half of which are yet to be formally described.

Unfortunately, terrestrial ecosystems on the island are in decline, with logging and agriculture posing particularly severe threats. But there is growing interest in safeguarding New Guinea’s biodiversity and, though much progress is still to be made, descriptions of new species and techniques for identifying them are likely to bolster these initiatives.

If nothing else, the discovery of P. viserion and P. drogon, currently known only to New Guinea, may give Game of Thrones fans a reason to appreciate conservation efforts in this often-overlooked patch of the south Pacific.

Thomas O’Shea-Wheller, PhD Student, University of Bristol

This article was originally published on The Conversation. Read the original article.

The Conversation

microtugs

Six cockroach-sized micro robots tow a 3,900-Pound Car

Inspired by ants, researchers mimicked the insects’ individual super strength and collective hive mind in tiny robots. Each weighs only  0.2 pounds, but six were enough to tow a 3,900 pound-car, with one of the researchers seated as well. The scientists behind the project say the experiment is equivalent to six people trying to move the Eiffel Tower and three Statues of Liberty (on wheels).

microtugs

BDML / YouTube

The researchers at Stanford’s Biomimetics and Dextrous Manipulation Lab found that robots that have jerky motion are inefficient in groups. The robots they made, called  μTugs, are better at pulling weight thousands of times their own by sustaining the pulling force for a longer duration. Critical in this respect is their ultra sticky ‘feet’ that mimic another famous feature from the animal kingdom — the gecko’s sticky pads. Previously, the same Stanford researchers built tiny bots that could scale walls owing to these artificial pads.

This adhesive, combined with team work, allowed the  μTugs to perform this amazing feat.

“By considering the dynamics of the team, not just the individual, we are able to build a team of our ‘microTug’ robots that, like ants, are superstrong individually, but then also work together as a team,” David Christensen, a lead researchers, said.

The whole setup will be described at length in May, at the International Conference on Robotics and Automation in Stockholm.

via The Verge

Ant colonies behave as a single superorganism when attacked

Ant colonies are incredibly complex systems — the tightly knit, intensely cooperative colonies are closer to a single superorganism than to human societies. Researchers form the University of Bristol wanted to know how this single mind of the hive reacted to distress, and subjected colonies of migrating rock ants to differing forms of simulated predator attack to record their response.

Led by Thomas O’Shea-Wheller, the researchers subjected ants to simulated predator attacks to investigate the extent to which colonies of rock ants behave as a single entity.
Image via phys

By studying the ants responses, the team observed different reactions depending on where the attack was performed. When targeting scouting ants, that stay primarily at the periphery of colonial activity, the “arms” of foraging ants were recalled back into the nest. But when they targeted the workers at the heart of the colony, the whole body of ants retreated from the mound, seeking asylum in a new location.

The team was able to draw some pretty interesting parallels with human behavior. The first attacks could be compared to burning your hand on a hot stove, while the ones centered on the workers were more dangerous, kind of a ‘house on fire’ scare. And in each scenario, the ants reacted surprisingly similar to any animal with a nervous system — an involuntary reflex reaction to retreat from the damaging element in the first case, and a flight response from a predator that can’t be defended against in the later simulations.

“Our results draw parallels with the nervous systems of single organisms, in that they allow appropriate, location dependent, responses to damage, and suggest that just as we may respond to cell damage via pain, ant colonies respond to loss of workers via group awareness,” said Thomas O’Shea-Wheller, a PhD student in Bristol’s School of Biological Sciences and one of the authors of the study.

longhorn crazy ants

How crazy ants carry dinner 100 times their size: coordination and individual leadership

Different ant species employ various tactics to forage food and keep the colony in tip top shape. Most often scouts will scour for food, and when a source is deemed fit a trail of pheromones guide worker ants to pick up the crumbs, leftover pizza or cheerios. Ants aren’t very picky, you know. What they are is very strong. It’s common knowledge that ants carry loads multiple times heavier than their own weight. Some species, like longhorn crazy ants are able to carry some of the biggest loads among ants by working together, joining in a band to perform the lifting. It’s a curios matter, one you might have often noticed in your very own backyard.

longhorn crazy ants

Longhorn crazy ants work together to move great loads.

Simply by watching the longhorn ants, assisted of course by the latest motion tracking technology, a team of researchers at  the Weizmann Institute of Science in Israel documented this collaborative effort, which is quite rare in the animal kingdom. The ants in question are labeled as crazy because of the erratic paths they make to and fro foraging sites, often moving in zig-zag. It didn’t register at the beginning, but soon enough Ofer Feinerman of Weizmann found the ant brigade’s chaotic behavior made sense and in doing so found that ants – individual ants – are a lot smarter and independent than we might think.

Imaging having to move a couch down stairs or past a block with your friends. If each would pull and tug in his own direction, then the couch won’t go anywhere and all of your collective efforts would have been spent for nothing. By carefully coordinating yourselves, you and your friends can move that couch. For this to happen, there needs to be a leader: “be careful, there’s a turn there”, “slug it this way” and so on. The leader of the couch-moving maneuver can, of course, be anyone in the group, taking turns. The crazy ants work in a similar way, the researchers found.

Fresh help arrives to help the movers.

Fresh help arrives to help the movers.

The researchers placed longhorn crazy ants in a dotted arena littered with obstacles, but also food. By carefully analyzing their movements, the team built a model that revealed the band of ants move food by keeping their brigade fluid. When the ant brigade teams up to carry a load, after a while they lose sense of the track they need to take. So a leader scouts a bit ahead, returns to the pack a pulls the weight towards the right direction. The ants take turns as a the leader, with each ant taking on the role for as little as 10 to 15 seconds. This explains the zig-zag.

“The individual ant has the idea of how to pass an obstacle but lacks the muscle power to move the load. The group is there to amplify the leader’s strength so that she can actually implement her idea”

The ants eventually managed to tug this huge load for 16 centimeters. They were unable, however, to navigate it past obstacles.

The ants eventually managed to tug this huge load for 16 centimeters. They were unable, however, to navigate it past obstacles.

When the load is too great or when there are too many obstacles, the ants can’t seem to carry the load. They have the muscle power to do it, though. Just bring in more ants. The larger the group, the harder it is to coordinate the whole movement, though. So, there’s a certain sweet spot, the researchers say.  “Too many cooks spoil the broth,” says Vijay Kumar, a mechanical engineer at the University of Pennsylvania who studies collective animal behavior who wasn’t part of the study.

“Usually when people talk of ants they have this very romantic view that one ant is really stupid, but if you take many ants you get something very smart—an emergence of intelligence or something like that,” says Feinerman. “If you look at this system it looks like the intelligence of knowing where to go and how to pass obstacles does not come from the big group. The big group just gets stuck at the big obstacle and they never pass it. The problem-solving abilities come from the single ant who knows which way to go to pass the obstacle.”

ants-love-Junk-Food

City ants LOVE junk food

If you ever dropped food on the pavement, don’t feel too bad. It’ll get scrapped bit by bit by the ever resourceful ants, so you’re actually doing a favor to these swarms of critters. But have you ever wondered why ants can eat ice cream, hot dogs or just about every kind of junk food we unwittingly throw at them? Some researchers looked at this question and found that some particular ant species have seemingly adapted to consume junk food.

ants-love-Junk-Food

Image: Apex Beats

“The ants that live alongside us in our cities also seem to be those very same species that can consume the similar meals that we do, and do so the most,” Clint Penick, a post-doctoral fellow at North Carolina State University.

Dr. Penick and his team collected 100 ant specimens from 21 species living in various urban settings in New York City, then analyzed their bodies for carbon isotopes. We use carbon isotopic data for exactly the same reason that we use oxygen isotopic data: to find out from where the atoms in a specific object (e.g., an animal or plant) are derived, and what their history has been. The history of carbon atoms in living organisms involves how the organisms obtained these carbon atoms. This is why it’s such a great tool for dating artifacts or fossils. In our case, the researchers studied the isotope concentrations to see how much junk food the ants where eating.

Foods that are heavily based on corn or sugar cane (fundamentally, all processed foods) and meats have a tendency to be enriched in carbon 13. The researchers found that those ants that live closer to humans had much more C13 in their bodies. Ants found in medians had higher levels of carbon-13 than those found in parks, for instance. Only one species, Lasius cf. emarginatus, didn’t particularly enjoy junk food, despite living close to humans. The species, however, is a newcomer to NYC. This suggests that ants have adapted to consume food meant for humans.

“Human foods clearly make up a significant portion of the diet in urban species,” Penick says. “These are the ants eating our garbage, and this may explain why pavement ants are able to achieve such large populations in cities.”

The findings were reported in Proceedings of the Royal Society B..

Tawny crazy ants (Nylanderia fulva) attacked by rivaling fire ants (Solenopsis invicta). To protect itself against the deadly fire ant venom, crazy ants secret a venom of their own that cancels the other. When the two mix, a new substance whose class has never been encountered in nature emerges. Photo: Ed LeBrun

First naturally occuring ionic liquids found in ant venom mix

Tawny crazy ants (Nylanderia fulva) attacked by rivaling fire ants (Solenopsis invicta). To protect itself against the deadly fire ant venom, crazy ants secret a venom of their own that cancels the other. When the two mix, a new substance whose class has never been encountered in nature emerges. Photo: Ed LeBrun

Tawny crazy ants (Nylanderia fulva) attacked by rivaling fire ants (Solenopsis invicta). To protect itself against the deadly fire ant venom, crazy ants secret a venom of their own that cancels the other. When the two mix, a new substance whose class has never been encountered in nature emerges. Photo: Ed LeBrun

Ionic liquids (IL) are basically liquid salts with very low melting points. These are heavily used in industry as solvents for chemical processes or as performance enhancers, part of electrolytes or lubricants. It’s only recently that an ionic liquid has been found to occur in nature, after a team of researchers at University of South Alabama found that the substances forms when two ant species mix their venom.

[ALSO READ] Invasive ant has bear trap-like jaw that can propel it through the air

The team led by Prof. James Davis was studying two ant species fighting over territory: fire ants (Solenopsis Invicta) and tawny crazy ants (Nylanderia fulva). Fire ants and tawny crazy ants are native to South America, where their battle may have raged for thousands of years. Fire ants arrived in the United States first, sometime in the 1930s. The crazy ants didn’t start to show up until the early 2000s.

When the fire ants would sprinkle the tawny crazies with their venom, the latter would respond by secreting formic acid, their own venom, to groom and rid themselves of the poisonous attack. When the two substances mix, a viscous ionic liquid containing a mixture of different cations along with formate anions forms.

[AMAZING] Fire ants build rafts to protect against floods

The properties of the resulting mixed-cation ammonium formate milieu are consistent with its classification as a protic IL.  Seeing how the IL was discovered by accident, it’s very much likely that other naturally occurring ILs might be discovered.

It’s interesting to see how well the crazy ants have adapted to fire ants’ venom. In a separate study, Edward LeBrun, a researcher at the Fire Ant Research and Management Project at the University of Texas at Austin, found when crazy ants were prevented from secreting the antidote after being brushed with a bit of nail polish on their abdomens, 48% of them died when exposed to fire ants. When they were allowed to secrete the antidote, 98% survived.

Finding appeared in the journal Angewandte Chemie International.

Farmer ants draft parasite ants as mercenaries

Ants are absolutely fascinating creatures. Not only have they discovered farming and animal husbandry thousands of years before us (sometimes even using bacteria to grow gardens), they also conduct executions for the good of the colony, follow Fermat’s principle of least time, and as it has been shown now, draft parasite ants as mercenaries.

Just like medieval cities sometimes recruited expensive contingents of mercenary soldiers to ward off invaders, farmer ants sometimes recruit parasite warrior ants to fight for them, as it is neatly illustrated by this video.

Entomologists investigated a type of ants called Sericomyrmex, which raise fungus in gardens. They are what you would call farmer ants, living on peacefully in their day to day activities. But they have a problem with a type of parasitic ants named Megalomyrmex. These species has cunning queens which stealthily enter and colonize the gardens of Sericomyrmex and can feed on their offspring and their fungus for years before they are detected and stopped. They even cut off the wings of the virgin queens of Sericomyrmex, thus halting the spread of further colonies.

Evolutionary biologist Rachelle Adams at the University of Copenhagen has studied this stunning phenomena for over 10 years; she noticed that at some point, these parasites can make up to 80 percent of the entire colony, which doesn’t really seem to make any sense.

“This prompted me to question why this might be, leading me to focus my collecting efforts on this particular system,” Adams said.

So she put ants to the test: she took the farmer ants and exposed them to another common threat to them: Gnamptogenys. This is also a type of parasitic ant, but they’re way more threatening: they come, pillage the fungus gardens and destroy everything. However, when exposed to this threat, while the farmer ants went into hiding, the Megalomyrmex rose up and fought the invaders off – and then it hit her! Sometimes, they are not truly parasitic, but instead, are fed and tolerated in order to protect the colony.

Copyright: Anders Illum.

Copyright: Anders Illum.

“The guest ants are the better of two evils,” Adams explained. “If the raiders were not a threat, then the guest ants would only be a burden to the host colony.”

Indeed, this theory was confirmed by further research – she noticed that invaders only attack colonies without ‘mercenaries’.

“If we studied just the farming ants and the guest ants, we would have missed this important discovery and concluded the guest ants are simply parasites,” Adams said. The researchers compared this tradeoff to sickle cell anemia, a hereditary blood disease that can cut lives short but also gives people resistance against malaria.

The research team also highlighted that Megalomyrmex conducts a type of chemical warfare.

“The raider ants attacked by the Megalomyrmex were often attacked by their own nest mates,” Adams said. “This suggests that the guest ant venom disrupts the recognition system of the raiders, causing sisters to attack and kill one another.”

This just goes to show that relationship between ants, and likely other insect species are simply far more complex than we have judged them so far. We should keep in mind that every additional interaction brings an entirely new complexity and should change the way we perceive the situation.

The scientists detailed their findings online Monday in the journal Proceedings of the National Academy of Sciences.