Recently in Ant behavior Category

Ant mating


Dear AntAsk Team,
Honey bee queens mate something like twenty times over a few days. That sperm then lasts for say 3 or 4 years. In the long lived queen ants how many times do the queens mate? And does that mating period last for their twenty odd year lifespan?

- Geoff

dorymyrmexbureni_casent0103862_p_1_high.jpg
Figure 1. Copulating pair of Dorymyrmex bureni. The male is the small individual attached at the end of the large queen. Note that both individuals have wings. The queen of this species will probably only mate once.

dorylusnigricansq_casent0172663_p_1_high.jpg
Figure 2. Queen of Dorylus nigricans molestus. The highly specialized queens of Dorylus are wingless and must mate with multiple males before founding a colony, which they do by taking a proportion of the standing worker population with them.

dorylusnigricansm_casent0172663_p_1_high.jpg
Figure 3. Male Dorylus nigricans molestus. Males of Dorylus are massive and distinctive animals which probably only mate once in their life, unlike the queens, and which have bizarrely modified genitalia.

cardiocondyla obscurior males fighting_sylvia cremer photo.jpg
Figure 4. Male Cardiocondyla obscurior engaged in mortal combat to mate with their sisters inside the nest. Photo by Sylvia Cremer.


Dear Geoff,

This is a great question which has several facets to it. In general, queen ants mate only during a very short period of time, such as a few hours during a nuptial (mating) flight (Fig 1.) or for a few seconds to several hours by calling males to her with chemical pheromones or with other signals (Figs. 2, 3). Regardless of how the queen is able to obtain sperm, she is stuck with this for the duration of her life. To the best of our knowledge, queen ants never re-mate, even in lineages which have extraordinarily long life-spans. There are several intriguing aspects to the reproductive biology of ants, but one which relates to your question is the number of males a queen mates with. In that single short period of time in which a queen will mate, she may mate with one or up to a dozen males. Usually queens will mate with one or a few males, but in some cases queens seem to never mate more than once, such as in the Carpenter ants (Camponotus) which have been studied and in ponerine army ants (Simopelta). In other lineages queens will always mate with several males. These lineages usually have massive colonies with complex social organization. Examples are the leaf cutter ants in the genus Atta, and in the New and Old World army ants Eciton and Dorylus (Figs. 2, 3), respectively. Because matings occur only once in a queen's and male's lifetime males only produce enough sperm for that single event. A remarkable exception to this is the genus Cardiocondyla (Fig. 4), where some males fly from the nest to mate and die, and other, wingless males remain in the nest and copulate with their sisters after killing their brothers. These wingless and incestuous males are able to continuously produce sperm so that they may monopolize the virgin queens eclosing from their pupal cocoons. Despite the detail I've provided in this email, much remains to be learned about the reproductive biology of ants---from both the queen's and the male's perspective.

All the best,
-Brendon Boudinot & the AntAsk Team

Weaver Ant Farming



Dear AntAsk Team,

Weaver ant larvae is a commodity here in Indonesia, we use weaver ant larvae for dietary supplement to improve the performance of songbirds before bird singing competition and carp fishing bait. Throughout the year weaver ant larvae is harvested and sold, because demand for weaver ant larvae has increased in recent years some areas are being over harvested and as a result diminishing in weaver ant colony in the nature.
From that point, I and some friends trying to establish a weaver ant farm so we could meet the demand for weaver ant larvae and by doing so also help to reduce over harvesting in the nature.

Right now we have 42 jar of weaver ant nest in our colony which started from 30 jar of nest (the farming have started 1.5 month ago).
The diet of our farm is sugar water, caterpillar, crickets, diluted honey, diluted white egg, diluted fish oil.
Note: we haven't tried to harvest the larvae. Attached pictures of our farm setup.

DSC_0007.JPG DSC_0195.JPG

My question is:
1. Is it true that weaver ant tend to grow in population the most in shaded or dark places(because of these rumor we build a shed using paranet)?
2. What diet is the best for weaver ant to produce more egg?
3. After 1.5 month from the initial start now our weaver ant produce less and less egg what could go wrong?
4. How to join the antblog? I registered but there is no confirmation e-mail for activation.
Thank You in advance. I apologize if I'm not courteous enough or there is any mistaken words since English is not my native language.

Best Regards,

Mario


Hello Mario,

Thanks for your questions, and congratulations on your initiative: edible insects are the way to go!

We contacted an expert on many aspects of Oecophylla biology, Dr. Joachim Offenberg; and here is what he had to say:

"1. In nature they prefer sunny places for their leaf nests. However, as it looks like you keep the ants in plastic bottles it may be better under shady conditions as the bottles are transparent and temperature may build if exposed to direct sunshine. You can find a study on this issue via this link. On the other hand, the ants prefer temperatures usually above 30 degrees Celsius. Brood development increases with temperature.

2. The diet you describe seems to be adequate for the ants but it is important they have ad libitum access to a 20-30% sugar solution (they seem to prefer sucrose) and also remember to provide pure water ad libitum. In general they accept most types of protein but they prefer it in a wet condition. I.e. fresh rather than dried meat and fish etc. As insects are their natural source of protein it think it would be wise to include insects to some extend in their protein diet.

3. First of all you need to be sure that you do not mix nests from different colonies. In that case they will fight each other rather than producing offspring. Secondly you need to be sure that the maternal queen of the colony is included in your ant farm. The maternal queen (the queen without wings) is the only member of the colony that can produce eggs that are able to develop into brood. Weaver ant colonies will not accept introduced queens which makes it important to find the maternal queen of the colony (which can be difficult!). A last reason for limited brood production could be limited availability of space in the ant farm. I know from my laboratory colonies that colonies that live under limited space, reduce the production of new workers, since the colony is able to match the production of new workers to their actual need. I do not, yet, know the mechanism behind this regulation and have therefore not found a way to trick them to continue a high brood production. If you find a way I will be happy to hear about it!

4. Lastly, it is important to protect the ant farm against smaller ant spices as e.g. Pheidole spp., crazy ants etc. They like weaver ant larvae as much as the birds and are in many cases able to win a fight against weaver ants.

Good luck with your ant farm and best wishes,"

Joachim Offenberg, Flavia Esteves & the AntAsk Team

p.s. Mario, you began your AntBlog membership when you sent your questions to us! We really appreciated that, and hope to hear more interesting questions from you soon!
p.p.s. Your English is great!


Hello, I am in Toronto and have located a colony of small reddish/brown ants living under the 6x6 wooden ties surrounding my lawn. My question is: are these ants beneficial to the eco-system and should therefore be simply left alone? I have a wooden porch: should I be concerned about 'an invasion'?
Secondly, I have occasionally seen the same type of ants moving in mass across sidewalks - thousands of them - so many that it looks like a brown stain on the sidewalk. Can you tell me what causes this phenomenon?
Thanks for your help,

Mary


Dear Mary,


Thanks for writing to the AntBlog! It was a pleasure to answer to your interesting questions.

Ants play a huge role in an ecosystem: they are diverse (we estimate 30,000 ant species living on Earth), and are in great numbers everywhere (all the ants weigh almost the same as the 7 billion human beings). Along their evolution, ants established ecological relationships with a large array of plants and animals. They are prey, predators, symbionts, parasites (there are even slave maker ant species!), seed dispersers, pollinators, and so on. Ants move more soil than earthworms. They impact and are impacted by almost everything surrounding them. More, they have a short lifespan, and that means their nest population is constantly being replace by new generations of ants. So, if something happens with an environment you will notice the effects faster and with more details if you look at the ants, and it will be much more effective than looking at birds or mammals, for example.

Just for curiosity, ants are important for other aspects of human societies. Their behavior is used as model to create smarter traffic lights, or to develop software that will evaluate the response of our bodies to the effect of new drugs (see here, here, and here). Anti-inflammatories, antibiotics, and even drugs to fight against cancer were/are being developed with substances ants secrete (here, here, here, here, and here). Finally, have you ever thought of including ants in your menu? Many human cultures around the world did! See here.


Salad of Oecophylla smaragdina queen brood mixed with some worker ants, mint leaves, spring onion, chili, and fish sauce. Popular in Thailand and Laos. Image by Joost Van Itterbeeck/AntWeb.org

Based on the behavior you described, I believe you found pavement ants (genus Tetramorium). Unlike carpenter ants (genus Camponotus), pavement ants don't cause any structural damage to your house (and just to take Camponotus out of the fire, those ants nest in decayed wood; so, if the wood in your house is in a good shape, carpenter ants will not be a problem).

Pavement ants get their name because they nest usually underneath or at the edge of sidewalks, and other hard surfaces. They are an introduced species from Europe; and in your garden they will: harvest seeds -- some of which will eventually grow around their nests; tend insects on plants, collecting sugary dropping they produce (A.K.A honeydew), and protecting them from predators; and predate other insects.

The pavement ant workers are dark reddish-black, about 2.5-4 mm long; the petiole, which connects the mesosoma (i.e., the modified thorax of ants) and gaster (modified abdomen), has two segments. The posterior part of the mesosoma has two spines that project upward, and they have a stinger in the last abdominal segment.


Lateral view of Tetramorium caespitum. Image by Will Ericson/AntWeb.org

When two pavement ant colonies overlap, worker ants leave the nest to establish their territory boundaries before ants from the other nest push them out of there. Then, ants coming from each nest collide in a massive battle. The combats are sometimes ritualized: they will just size each other strength, and produce very few casualties. In another occasions, they will ripe one another apart, and thousands of corpses will be left on the sidewalk afterwards.


Sidewalk ant war. Image by the fabulous Alex Wild (www.alexanderwild.com)


Cheers,

Flavia Esteves and the AntAsk Team


Hi,
We have a sudden ant infestation. Nothing works to get rid of them so we are going to ride it out I guess. Must be the drought in California? I have a question though. They often congregate in our shower. Even when and especially when it is dry in there and no one has showered since the morning. Today, I went in and there were a number of trails leading to perfectly formed circles. The circles had the ants facing inwards and their bodies/tail ends pointing outwards. I wish I would have taken a picture but I was upset and I washed them away. It wasn't a moving circle. It was a stationary size of about a nickel circle. Much like a synchronized swimming event. Is this a meaningful event? Are they talking about leaving my house in this circle? I sure hope so. Thanks for answering me or replying back to my email if you have time. Oh and they are small little black ants - if that matters.

Mary


Dear Mary

The ant that is visiting your house is most likely the argentine ant. The move inside when it is too dry outside or too wet. As you have noticed there is many advantages to these visits - one is that you are presented with a convenient chance to observe nature in the comfort of your own home. Why are they forming a circle - well there must have been some resource there - residue from the evaporated water (salts most likely) that the ants were feeding on. If inclined you could give them a drops of water with food coloring in them and watch them change colors:

article-2022765-0D4E92FF00000578-678_634x466.jpg

You can read more about the sudden movement of the argentine ants into homes in California at: http://www.sfgate.com/bayarea/johnson/article/Meet-the-bad-ant-that-s-overwhelming-California-5719954.php

With regard to control, I strongly advise a green approach. First, seal the cracks where the ants are entering. Next if the ants in the house are a problem, then just vacuum them up. Outside if you want to control the nest, apply boiling water (lots of it). Chemicals in your house will be a permanent risk to you and others and outside when applies will be a containment to wildlife and water supplies.


Best, Brian Fisher and the Ask AntWeb Team

Ant social status



Hi, I was curious if ants have a social status within their sub sectors (worker, male). How do they obtain a higher status? And if so does this give them more privilages (ie a bigger living space, more food, first breeding rights).

HUB


Dear Hub,

Thanks for writing to the AntBlog! We contacted an expert on many aspects of ant biology (behavior, colony reproduction, nest architecture, population dynamics, among others), Dr. Walter Tschinkel; here is what he had to say:

"Hello Hubert,
You asked AntBlog whether ant have social status within their colonies, and whether such status might be connected to certain individual advantages and benefits.
The simplest answer is that social status in the sense that we know it within vertebrate societies does not exist in ants. It is helpful to think of ant colonies as analogs to organisms (hence, we often call them superorganisms). Every individual is engaged in helping the colony produce more colonies, just as every cell in an organism is engaged in helping produce more of that organism. In the ants, there is only one (or a few) individual(s) capable of direct reproduction (the queen), while in an organism, only the germ-line cells in the gonads are capable of making gametes and subsequently more organisms. In this light, you can see that different sectors of the colony may be allocated differing amounts of resources, but such allocation serves the needs of the colony as a whole, rather than any individual within it. The individual ants making up the colony are simply the machinery needed to make more colonies.
One of the basic mechanisms that organizes colony function is division of labor (or function). The most basic division of function or labor is reproductive -- most of the ants in a colony are more or less sterile workers, while only one (or a few) individual is capable of mating and laying eggs. Most of these eggs develop into more workers because workers are short-lived and are continuously replaced, whereas the queen has a long life span (in many cases, equal to the life span of the colony). The second principle that organizes the colony is that the workers change jobs as they age. Young workers mostly take care of larvae and pupae, and as they age they switch to more general nest maintenance, food processing, transport within the nest and so on. Only the oldest workers leave the nest to forage, bringing back food for the rest of the colony. Once they begin foraging, their life expectancy is very short (a few weeks).
This change of jobs parallels an upward or outward movement of the worker within the nest. Young workers are born in the deeper parts of the nest, move upward as they age and change jobs, and finally appear near the surface, whereupon they become defenders and foragers during the last part of their lives. There is thus a continuous upward and outward flow of workers. The image here shows a cast of the nest of the Florida harvester ant, Pogonomyrmex badius, and summarizes these movement and labor patterns within the nest.

Once you see the parallels between organisms and superorganisms, you see that division of function or labor is central to both, and that differences in allocation serve the entire entity. The relative size and activity of the liver, or kidneys or circulatory system of an organism serves the entire organism, and any deviation from some norm can be detrimental to the function and fitness of the organism. Similarly, the patterns of division of labor in ant colonies serves the success and fitness of the colony as a whole. The workers are just the gears in that machine."

We hope this answers your question,

Walter Tschinkel, Flavia Esteves & the AntAsk Team

Cohabiting ants


Hi there, loving your page!

I am on holiday in Andalucia, southern Spain, and right by our front door there is a colony of what look like harvester ants. No more than fifteen centimetres away there are some holes from which some very tiny red ants emerge, about a quarter of the size of the smallest harvester ants. Are these two separate colonies, or different types of the same ant? They don't look related and they don't appear to cross into each others territory. I would have thought they'd be fighting all the time if they're not related. Why might this be? Are their diets different enough that they aren't in competition? Sorry to bombard you with questions!

Kind regards,

Ian


Dear Ian,

Greetings from San Francisco, and thanks for writing! We contacted an expert on taxonomy and ecology of Europe and Macaronesia ant species, Dr. Xavier Espadaler; here is what he had to say:

"It is not an unusual situation for different ant species to have nest entrances rather close. Coexistence is a possibility; fighting is another possibility. But if the two societies are already nesting close to each other, it is likely that they differ in some way, in their daily activity cycles, or in their food habits.

It is possible that the harvesting ants (Messor) are living close to a Pheidole pallidula nest. This last species is all too common in Andalucía. Their nest, with one or a few entrances, is usually surrounded by the tiny remains of the scavenging they do upon any kind of arthropod remains or corpses; they may capture living prey as well, if small enough. The remains look like a dark zone, somewhat semicircular, bordering the nest entrance. If you are able to look at them under a magnifier, you would see shining heads, wing or leg or thorax fragments, that are the non edible parts of their foraging."

Hope this helps,

Xavier Espadaler, Flavia Esteves, & the AntAsk Team



Hello,
When comparing human infrastructure and ants what would you say is their most common behaviors? Do you think there is anything humans could learn from ant behavior?

Dear Jacqueline,

When human designers, architects, engineers, and computer scientists turn to other organisms for inspiration, it is often referred to as "biomimicry." In recent years, more and more people have turned to the other species on Earth for inspiration. Recent and ongoing work in Biomimicry is highlighted in this TED talk (by the main popularizer of the term "Biomimicry").

However, the speaker doesn't mention much about ants (and neither have I, so far...). One of the reasons ants are so interesting is that they display a wide variety of life-styles, from farming fungi, to raiding termite nests, to foraging in the shifting sands of the desert. And they're able to do all this with very little of what I would call "individual-level intelligence." Ants, like other social insects, function without central control, using what has been referred to as "swarm intelligence." (for more of my ramblings on swarm intelligence, see a previous post here, and also this more coherent article from National Geographic).

So, by studying ants and other social insects (like bees, termites, and certain wasps), we can learn more about true, blind democracies, and how to get things done without central control. For example, by studying processes different kinds of ants (and other social insects) use to find food and tell each other about it, computer scientists and engineers have been inspired to think of new ways to route traffic, solve resource distribution problems, and perhaps even program robots. The tricky thing about biomimicry right now is that many of these are still just potential lessons we could learn from ants - they haven't yet changed the way we get things done in our own lives.

The other tricky thing about biomimicry is that, like things you read in a blog post, sometimes what seem to be cogent lessons need to be evaluated and taken with a grain of salt. For example, in this article, the author uses the example of fungus-growing ants as a system of agriculture that we should learn from (perhaps just because of that charismatic image), but in the same paragraph alludes to the dangers of monoculture, which is exactly what fungus-growing ants (and termites) do: they cultivate a single species of fungus. They can get away with it, because they've evolved the ability to secrete antibiotics and fungicides from glands in their bodies, and they have the labor power to strip acres of vegetation around their nest and bring it back to fertilize their gardens (the most charismatic ants that farm fungi are the leaf cutter ants; other types of fungus-farming ants and termites use some combination of things like soil, partially decayed vegetable matter, the exoskeletons of dead insects, and caterpillar frass to fertilize their fungal gardens). Worse, there are different kinds of ants that make slaves of other ants, ants that are very lazy (surprise!), and ants that just hang from the ceiling all day collecting sugar water in their abdomens (which I would probably try for a while, but might lead to diabetes after a few weeks). So just like the Japanese scholars studying at the "Institute for the Study of Barbarian Books" in the 1800s did with knowledge from "The West," we should study nature (ants included), but pick and choose which lessons to incorporate into the society we wish to build for ourselves.

Hope this helps!
best,
Jesse Czekanski-Moir & the AntAsk Team

Can I train ants? (Ryan)




Hello Antblog,

I am interested in conducting some experiments with ants and I had a few questions I'd like to ask before I get started and I thought your site would be a good place to start.


1) Can queens of different varieties be trained(forced) to co-exist in one colony if an abundance source of food is present?

2) What is the smartest breed of ants?

3) Could ants in an ant farm learn to farm aphids? How might I go about doing this?

4) Could ants survive on honey alone?

5) Could ants be trained to use little man made tools for things such as cutting or digging through rock?

6) Can ants smell and identify different metals such as iron, nickel, gold, etc.?

I understand these questions are very vague and I do not expect a direct answer for all of them, but any information is appreciated. I'd even like additional links I could go explore myself.
I am only a grade 12 student but I am very interested in ants. My ultimate goal is to create a super ant farm to test the capabilities of ants as well as teach them to advance as a species.

Hi Ryan,

I apologize in advance: this post is probably too long and too speculative. The answers to a few of your questions are simple: (6) I don't think so; (4) some ants can; (3) it's thought that this is not a learned behavior, but some ants do facultatively tend aphids; (1) no, unless they are social parasites (for more stuff on social parasites, click here, here, and here).

Questions #2 and #5 are pretty complicated, philosophically and biologically, so I'm going to spend most of the rest of this post talking about them.

But real quick, before I dive into a heady diatribe about the philosophy of psychometry: ants and honey:

Could ants survive on honey alone? Adult ants don't need very many nutrients, and can survive for at least a week or two (often more) on just sugar water or diluted honey. It is the egg-laying ability of the queen, and the growth of the larva that depends on more protein-rich food sources, like (depending on the ants) seeds or insects. Several groups of ants seem to have bacteria living in their guts that can help them make nitrogen (one of the important building blocks of life that we need to synthesize proteins), but I'm not sure if anyone has quantified how only raising these ants on carbohydrates influences how many eggs the queen can lay, and how fast the larvae can grow. For many ants, we don't know their exact dietary requirements, but by and large, the ants that are most likely to be able to get by on a sugar-water or honey-only diet are arboreal (spend most of their time in trees). Carpenter ants (genus Camponotus) and Acrobat ants (genus Crematogaster) are among the most likely candidates that you'd run into outside of the tropics. Similarly, with respect to your question (3), many of the same ants that are largely herbivorous will occasionally tend aphids or other related phloem-sucking insects. But I'm not aware of a learning component to this behavior: I think it's hard-wired.

Okay. Onwards and upwards.
You know, when I tell people that I study ants, I am often asked (by males especially) if I am working on weaponizing them or figuring out how to harness them for industry. Ants are, after all, famously industrious. There is even an ancient Greek/Indian/Russian legend about ants that mine gold (sort of). I read about it in the book "Shalimar the Clown" by Salman Rushdie (which is a great novel if you're interested in 20th century geopolitics, but doesn't have much useful information about ants).

In general, the major hurdle to training ants for any specific anthropocentric end is the way in which they actually get things done. Deborah Gordon has a really nice book about ant behavior called "Ant Encounters" that I highly recommend. One of the key aspects of ant behavior she does a really good job explaining (not least because she pioneered this research) is "emergence." Her research, and the research of other people who study social insects, is much of the inspiration towards work in "Swarm intelligence" in robotics and computer science. Basically, the problem-solving ability of the colony, or "intelligence" does not arise from the leadership or intelligence of a few ants, but emerges from the trial and error of many non-intelligent individuals. Thus, to train a swarm, you'd really need to understand how voting works in these true, blind democracies. Here are a few links you can check out if you want to learn more. Deb Gordon and Tom Seeley are some of the most eloquent speakers and important researchers on the biological side of swarm intelligence (read/listen/watch more here, here, and here).

The most compelling examples of humans modifying ant behavior are not the results of training, but of trickery. It's easy to get ants to walk where you want them to walk, think a given nestmate is dead, and become alarmed by isolating one of the pheromones they use to communicate, and applying it in the right way. However, I can't think of a way in which you could use pheromones to trick ants into picking up tools, or finding gold, unless you could splice the gene for pheromone production into a bacteria that preferentially grew and expressed that gene in the presence of that metal. This is not completely implausible, and as we learn more about the genomic architecture of ants, and the metabolic pathways involved in pheromone production, using a genetically-modified bacteria-ant system could potentially become economically viable (and probably less ecologically destructive than most current mining techniques). One could aerially spray genetically-modified bacteria over an area that already has high ant densities, using the bacteria to trick the ants into collecting soil particles with high concentrations of metal oxides. Then, a few months later, when the ants have collected the clumps of soil with the most metal oxides, one could find large ant colonies and spray another strain of genetically-modified bacteria directly into the nests, that would make the "dead ant" pheromone in the presence of high concentrations of the metal oxide. After a few days, one could go around collecting the midden piles at the surface of the nest, which would be enriched in the target metal oxide. This sort of strategy would probably work best in desert or grassland environments, where a few species of ants build conspicuous nest mounds, like Pogonomyrmex in the American Southwest. It's possible one might be able to do this chemically, without genetically modified organisms of some sort, but if there was a much simpler way of using ants to work for us, someone (especially in Greece, Russia, or India) probably would have figured it out.

Beyond pheromonal trickery, it is possible that we'll be able to eventually trick ants electrochemically, as you can "currently" (get it? like, electrical current?) do with cockroaches: https://backyardbrains.com/products/roboroach
It's possible that, by controlling one ant with electrical impulses, you could convince the rest of the colony to do your bidding. However, as Tom Seeley found with bees, nestmates might need to be convinces themselves of the validity of the scouts choice, in which case you'd need to coordinate quite a few ants to agree that, for example, a vein of gold is a food source. The trickery arguments above apply primarily to ants that often recruit to a food source; however, there are ants that primarily hunt alone.

As you may have figured out by now, your question "which ant is most intelligent?" depends on what kind of intelligence you're talking about. The types of ants most likely to exhibit high degrees of swarm intelligence are the ants that form the biggest colonies, and need to forage collectively. Leaf cutter ants (especially Atta and Acromyrmex) and army ants (especially Eciton and Dorylus) form colonies of hundreds of thousands of individuals in the wild, and many types of invasive ants (such as the Red Imported Fire Ant, Solenopsis invicta) form sprawling super-colonies that can cover acres in their introduced ranges. I'm not aware of a "swarm intelligence" test (but see Seeley's work on, for example, nest-finding abilities of honey bees in Maine), but the number of worker ants involved, the foraging range of the colony, and the complexity of the environment would all likely factor in. It would be interesting to compare how quickly swarms of different sizes and species could solve a maze, for example. I'm not aware of a study like this: perhaps you could set something up!

Observations of ants in the wild can allow one to make at least cursory qualitative statements about swarm intelligence in ants. The complexity and scale of leaf cutter ant nest architecture, the many tasks involved in maintaining a fungal monoculture, and the hazards of foraging in tropical savannas and forests leads me to suggest that the attines may exhibit the highest degrees of emergent, swarm intelligence, perhaps surpassed only by the fungus-growing termites of the African and Australian tropics. A foraging swath of army or driver ants (Eciton or Dorylus) may be collectively be processing millions of environmental signals per second: scent and vibrational cues about proximity of prey and colony members, light ant dark cues, etc., which is similarly impressive.

Basically everything listed in the paragraph about ants here (and the suspiciously similar list here) is a result of "swarm intelligence," and not at all related to the individual intelligence of any of the colony members. Personally, I don't think there is a clear winner between ants and termites in terms of the complexity that emerges from the swarm intelligence of their respective superorganisms. And I'm somewhat tempted to write a whole 'nuthur blog post on what is wrong with these two articles... perhaps some other time.

So far as individual, organism-level intelligence goes: again, I can only speculate. I am tempted to guess that the ants that have small colonies and have large workers that forage by themselves are most likely be more individually intelligent, because colony fitness will depend to a greater extent on the problem-solving ability of ants acting individually, rather than the emergence of intelligence from trial-and-error and blind democracy. Conversely, I would expect very small ants that live in very large colonies to be the least intelligent, individually, because, as a colony, they can rely on swarm intelligence to effect reproduction. In primates, the "social brain hypothesis" (also, see here) suggests that group size should be positively correlated with brain (neocortex) size. An assumption this hypothesis makes is that intelligence is necessary to maintain group cohesion through diplomacy, strategy, and individual recognition. In most social insects, group cohesion is pheromonally-mediated, so intelligence need not scale with group size. However, in some groups of ants and wasps, there is a shifting dominance hierarchy, which might mean individuals have to remember each other and behave according to past experiences. Elizabeth Tibbetts, to the astonishment of the behavioral and entomological communities, demonstrated face recognition in certain wasps with changing social hierarchies that are reinforced by in-fighting, rather than solitary wasps or eusocial wasps with hormonally-mediated social hierarchies. Thus, the ants that are most individually intelligent (e.g., the most train-able) may be ants that have shifting social hierarchies, and/or spend much of their time hunting by themselves. We're still learning more about the social lives of different species of ants: if you include species that haven't been described or discovered, there are probably more than 20,000 ant species in the world, and many of them have remarkably divergent ways of life. Several species I can think of which have to contend with a reality of changing dominance hierarchies (often due to unconventional reproductive strategies) throughout the lifetimes of individual workers, include ants in the genera Pristomyrmex, Platythyrea, Myrmecia, and Cerapachys. Myrmecia include some of the largest and most visually-oriented ants (two factors often correlated with increased brain size). They are also among the largest of ants, and very effective solitary hunters. So I would guess that some member of the genus Myrmecia might be the smartest ant, on an individual basis. Other strong contenders include ants that forage alone and use visual cues to navigate back to their nests, such as Gigantiops destructor, Cataglyphis, and Melophorus.

"Tandem running," a behavior in which one ant basically takes another ant by the hand and leads them to a food source (actually, they just tap each other's antennae pretty much the whole time) has been proposed as the first example of "teaching" in insects (by their definition, the "waggle dance" of bees is simply "broadcasting").
However, a critique of this article by some of the leading non-human intelligence researchers takes issue with this definition of learning, with implications for how intelligence might be defined (not to mention an implicit critique of the education system). Definitely check out the Lars Chittka's publications page for a veritable treasure trove of readings on insect intelligence.

Not to end on too preachy a note, but your statement "help them advance as a species" is problematic on two counts: (1) ants are a family, the Formicidae, which is comprised of more than 14,000 described species, and (2) "advance" has very strong teleological overtones. Teleology is an understandable (Nietzche was all about it, and would have been really happy with you for using that sort of reasoning). But it's not the way I think biology works. Saying you would like to domesticate ants, or modify them behaviorally or biologically so that they are more useful to humans is one thing, but the advancement of a species is an empty concept. Evolution is change, not change towards a goal.

To wrap it all up: swarm intelligence has many advantages at the colony level, but should not be confused with the individual intelligence of organisms. Without broad, cross-species comparisons of either kinds of intelligence, I can only speculate (perhaps beyond the limits of my own intelligence) about which ant is the smartest. Both types of intelligence would require different approaches to training or other types of behavioral manipulation. If there were an easy way to train ants for industry, someone would have probably figured it out by now. Emerging biotechnologies may make the use of ants (and/or ant cyborgs... cy-ants?) possible, but assembling little robots (equipped with both swarm and individual intelligence) from scratch might be prove to be easier, at least in the short run.

Whew! Was that enough to get you started? :)
Best,
Jesse Czekanski-Moir & the AntAsk Team

Territorial battles



Hello from Brookfield, Wisconsin.

It's great to see this service online--yet another wonder of the Web.

My question involves small (not much over a millimeter long), red ants that nest around our home and seem particularly to like areas near our front walk.

More than once I have noticed these guys flowing onto the concrete and forming a large gathering in the open air--see attached photos.

Why do they do this?

Thanks,
Ted

Small Red Ants 1.jpg

Small Red Ants 2.jpg


Hi Ted,

These are a species of pavement ant, Tetramorium caespitum. They are common in urban areas, hence their common name. The event pictured is a large territorial battle between colonies. Territoriality is common in ants as a whole, varying by species and colony age. Ants typically protect their territories for access to food or nesting space.

The closely related Japanese pavement ant, Tetramorium tsushimae, is similarly territorial to the pavement ants that you see in Wisconsin. In this species, colonies with larger territories containing larger numbers of seeds and other food resources are able to raise larger numbers of reproductive individuals. However, food is not the only factor determining colony success. The ideal temperatures for raising queens and males are between 27.5 and 30 degrees Celcius (81.5 to 86 degrees Fahrenheit) and colonies also engage in territorial battles to gain access to nesting sites with these temperatures. Therefore, the pavement ants on the sidewalks outside your house are probably fighting for access to both food and optimal nesting sites.

While fights among pavement ants often lead to the deaths of large numbers of workers, this is not a requirement for ants to maintain territories. A species of honeypot ant, Myrmecocystus mimicus, is also highly territorial, but, rather than risk the lives of workers, engages in ritual displays. Hundreds of ants from each competing colony confront each other and stand as tall as they are able while inflating their gasters to appear larger. Eventually, a winner is decided based exclusively on the differences in workers between colonies and territory is ceded to the apparently stronger colony. If colonies are drastically different in size then the smaller colony will be destroyed but otherwise, no physical interactions occur. You should take a look at the papers listed at the end of the post if you want to know more details.

Thanks for your question,
Ben Rubin, James Trager, & the AntAsk Team

Holldobler B. (1981) Foraging and spatiotemporal territories in the honey ant Myrmecocystus mimicus Wheeler (Hymenopera: Formicidae). Behavioral Ecology and Sociobiology 9: 301-314.

Sanada-Morimura S, Satoh T, Obara Y. (2006) Territorial behavior and temperature preference for nesting sites in a pavement ant Tetramorium tsushimae. Insectes Sociaux 53: 141-148.



Dear Ant Blog,

All the photographs I see show ants using their mandibles like tongs. Can they rotate them like we can rotate our arms?

Katrina

------------

Dear Katrina,

Despite the fact that ants use their mandibles for a multitude of different functions including prey capture, manipulation, and escape, there are no ants that have been proven to have fully rotational mandibles. Humans have a ball-and-socket joint that allows great range of motion, and although ants have a ball-and-socket joint for their antennae, their mandibles usually have a single plane of motion. Although this limits range of motion, it allows for much greater strength.

In case you are interested in reading more about mandibles, Chris Schmidt wrote a basic introduction to mandibular function as a part of the Tree of Life project. There are also several academic papers that detail the movements of mandibles (see Jurgen Paul), as well as some of the most extreme mechanical "trap-jaws" that have been convergently evolved by several ant species.

Hope this answers your question!

Best,

Max Winston & the AntAsk Team

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