Ant Wars

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Ant wars are a direct, aggressive form of interaction between ants from different colonies. Ants are involved in competition with each other. For example, if one of the colonies appropriates a food source, this source is no longer available to other ants. This is indirect competition. In the context of competition, ant wars are a form of conflict in which ants directly engage in fights with each other. Interestingly, such conflicts can occur both within one species and between species.

If we consider ants as a society, then there are two options for entering the so-called wars. One of them is quite close to the usual understanding of "war" for people, namely the fight between colonies of the same species. Another involves interactions between different species of ants. And both types of conflict are interesting for ant biology.

Research history

People knew about the existence of ant wars even before biologists were seriously interested in this phenomenon. For example, Charles Darwin wrote about conflicts between ants. There are references to the success of ant communities in the Bible, as people have been interested in observing this phenomenon for thousands of years. In part, the ant wars got so much attention because the clashes between ants were dramatic and obvious, but also because ants are social creatures just like humans, so it's hard to refrain from drawing parallels between our societies. It is interesting to view the history of these comparisons as a dialogue: on the one hand, the question aroused interest was whether the struggle between ants could reinforce existing ideas or open up a new side of human conflicts; on the other hand, the possibility of applying to ants the teachings that we have developed to understand the nature of conflicts among ants.

Research methods

Ants are social insects. As a rule, in insect societies, the colony acts as a whole and maintains genetic integrity to some extent. In other words, the colony is held together by a related structure, which is sometimes quite confusing. Within the colony, the ability to identify and recognize each of its members is developed. Ants tend to divide the world into two classes rather simply: the members of the colony and everyone else. Within the colony, very striking distinctive features are developed to unite it, at least in most species and under most circumstances.

Ants often encounter other ants, especially in the tropics. A recent study in the Appalachian Mountains in the United States showed how densely ants can settle. Researchers collected dead insects in the forest, left them on the ground and watched how long it took before a potential predator or consumer stumbled upon food. Most of these pieces of food were found by the ants, and it never took them more than a couple of minutes. In those places where anthills are located closest to the ground, ants constantly scan and patrol the soil, leaving practically no areas untouched for a long time.

Ants are more likely to encounter members of other colonies and even other species. In habitats occupied by many species at once, the probability of an interspecific collision of colonies is extremely high. This interaction happens regularly. If a colony realizes that there is a threat of loss of resources or territory from both ants of a different species and ants from other colonies of the same species, this threat is followed by an organized aggressive response, which can sometimes turn into a real battle.

Ant weapon evolution

Ants are ancient insects. They existed long before the split of the supercontinent of Gondwana. It happened over a hundred million years ago, and ants appeared long before that. Of course, ants have been at war for tens, if not hundreds, of millions of years. Ants have a range of devices that they can use as weapons during a fight. It can be assumed that wars played an important role in their evolution. Scientists studying the process of their evolution talk about the change in the object of aggression as they develop. In the distant past, the main enemies of early ants were vertebrates, such large land animals as dinosaurs, birds and mammals. Many species of ants were equipped with a very powerful sting. They were well adapted to attack humans, but their "weapons" were not very effective against other insects.

As ants evolved and their species became more diverse, the impact of these species on each other became more and more significant. This was the reason that other ants took the place of the main enemies of ants. It would seem that this is contrary to common sense, but some species of ants have lost their sting. In many cases, the sting was transformed into a supply system for chemical attack agents that could be successfully used in the fight against other ants. It looks like ants have deliberately given up the ability to fight vertebrates like us in favor of the ability to attack, fight back and win against other ants.

Nowadays, many ant species have a special arsenal of weapons that are not very effective against mammals, but work well against other ants. The sources and characteristics of these chemicals - in which part of the body they are formed and which chemicals are used - differ among all types. In different species of ants, you can find glands that are used during ant fights and are located literally in any part of the body. Chemical compounds are also extremely diverse. There were evolutionarily independent sources of these weapons, which evolved in different species of ants. At the same time, one can understand how differently they approached the solution of the common problem.

Ants have many types of weapons. Bites are commonly used. Often, ants act in concert: members of an attacking colony can hold members of another colony or tear the ants into pieces on their own, while their relatives detain the enemy. In fact, ants are very nasty. There is at least one species in which worker ants have a very large gland in their bodies. When these ants get very nervous, they can increase the pressure on her and literally explode, splattering everything around with a sticky substance. Other ants also have a variety of glands, sometimes located in the head and sometimes in the abdomen, and secrete toxic substances that knock down their enemies. Thus, their conflicts include methods that start with combat and end with chemical weapons, and this makes them akin to humans.

Make love not war

There is an interesting phenomenon that is almost certainly associated with human-made changes in the natural environment. Invasive species have been repeatedly invaded around the world. When a species introduced by humans gets the opportunity to master a new environment, it can breed to unimaginable scales, reaching a density unprecedented for its native habitat. The distribution area of invasive ant species can reach vast areas - thousands of square kilometers.

Why are these invasions so successful? The biology advantages of these species are associated with unicoloniality. This phenomenon consists in the loss in some species, for one reason or another, of the ability to distinguish between the boundaries of colonies. Under normal conditions, each colony has its own chemical signature, with the help of which ants distinguish between friend and foe. But many invasive species have lost it. Within their own species, they behave with other individuals as if they were members of their own colony.

The ability to avoid ant wars within a species and the desire to accept members of other colonies into their own allowed reducing the amount of costs. Therefore, they were able to increase the population size and become more successful in the competition. They retain the ability to view representatives of other species as enemies or aliens, but do not show intraspecific aggression. As a result, virtually one ant colony spreads over thousands of kilometers. Ants from one end of it can interact with ants from the other without any aggression. This effect has been observed many times and is quite surprising. The successful invasion species are not closely related but come from different subfamilies of ants, making them very diverse.

This tells us that cooperation is the surest way to success. Of course, much depends on the level at which it is expressed. We can turn again to the comparison between ants and human society. Humans are social animals: we work together, we form alliances. But ant colonies have a level of cooperation and integration that is practically unattainable for humans. A person almost always differs from an ant in that, even if he exists in a family or other social group, he retains a significant part of his individual identity.

We are always very excited about cases of self-sacrifice and generosity, and ultimately our life is a delicate maneuvering between selfishness and cooperation. In this sense, ants are different from us. Within the colony, selfishness and individual interests have largely ceased to exist. Ants continue to engage in conflicts between different colonies, but interestingly, invasive species that have abandoned colony barriers seem to be doing better.

Soldiers against nomadic ants

Soldiers are a special type of ants found in certain colonies. They are part of the workforce and specialize in defense. Not all ant species have soldiers, most are limited to just one type of worker. But in other species, specialized soldiers differ from ordinary workers in increased body size and behavior. If the colony is attacked, then it is the soldiers who take the most important part in its defense.

Nomadic ants are a subfamily of ants with several unique behaviors. They have developed their social skills more strongly than any other group of social insects, or even any other animal known to us. Nomadic ants are interesting due to their ability to perform all actions together. Any activity is carried out in close interaction of large groups of individuals. They do not take sole independent action, and individual workers never walk on their own.

The only members of nomadic ant colonies that are able to act independently are males. From time to time they are born as a mating colony. They have wings and leave the colony from time to time to find young females. Any other activity in the colonies of nomadic ants is carried out by a group of members of the same nest. Among them there are no separate scouts or foragers - everything is done by the mass work of a swarm of insects. You might think that a colony of nomadic ants is an indivisible unit, almost like an organism, like a pseudopod of an amoeba. A raid of nomadic ants can be thought of as an arm or a leg that never loses contact with the body. And everything they do happens with a high degree of coordination and interaction.

Nomadic ants with larvae stolen from a wasp nest

Nomadic ants provide excellent material for the study of ant wars. In this they are also slightly different from all other ants. For them, the world is divided into three categories: other colonies of the same species, other species of nomadic ants, and other animals, including other non-nomadic ant species. Their reaction to each of the categories is completely different. In general, nomadic ants do not take part in wars with other nomadic ants. However, one of the favorite prey for nomadic ants is other ant species.

Nomadic ants have two types of conflict responses: ignorance and avoidance. Imagine the process of foraging nomadic ants: they send out a large raid group, a whole carpet of worker ants, sweeping through the forest. Sometimes a similar swarm approaches a swarm of representatives of another species of nomadic ants. In such a situation, we expect to see an exciting battle between the two masses. However, most often they simply ignore each other: two huge swarms calmly pass through each other. The sight of this phenomenon is amazing.

The other type of reaction is very rare. When two colonies of the same nomadic ant species come into contact, they very quickly recognize that they have met members of the other group. But instead of starting a battle, both colonies retreat in the opposite direction from each other. They are ready to cover quite large distances in order to move away from each other as much as possible, which may even entail a shift in the entire colony. Thus, within their own species, nomadic ants show a clear avoidance, and representatives of different species simply ignore each other.

When nomadic ants encounter representatives of another, non-nomadic ant species, the opposite happens: they launch an attack and try to kill every ant in that colony. Nomadic ants attack very large colonies of other ant species, treating them as prey. Of course, other ants fight back in many cases. Such battles can result in heavy losses on both sides. The wars between colonies of nomadic ants and their prey are some of the most spectacular and disastrous battles in nature. Most often, nomadic ants prevail, but they can also suffer huge losses during the battle.

Nomadic ants are able to recruit large numbers of their nest cousins when they find a valuable resource. There is evidence that they have a special substance for use in such cases - a recruiting pheromone. This is an area for new research on nomadic ants and their chemical instrumentation. It has been experimentally found that they have functionally different pheromones and chemical signals to communicate different information, but we know almost nothing about their specific chemical composition.

In terms of physical size, nomadic ants are not always large. There are many other ant species with much larger body sizes. But they succeed thanks to the quantity. Their colonies are huge, and all actions are performed in large coordinated groups. If you come across representatives of a colony of nomadic ants, then we are not talking about one scout, but immediately about a significant part of the colony. At the same time, many individual ants emerge to fight and, unlike other ants, they do not have to wait until recruiting is complete. They interact with all elements of the environment as a separate social unit.

Nomadic ants versus leaf-cutting ants

One of the species of nomadic ants in the tropical forests of the New World regularly attempts to invade the territory of developed colonies of leaf-cutting ants. Nomadic and leaf-cutting ants are the crowns of ant evolution: they are able to create vast colonies, achieve a high level of socialization and participate in a multifaceted division of labor. When nomadic ants attack highly developed populations of leaf-cutting ants, soldiers of both species line up opposite each other and begin catastrophic battles that can last for days until the nomadic ants break through the line of defense, get to the nests of leaf-cutting ants and begin to plunder their supplies.

Leaf-cutting ants build huge anthills and establish vast colonies with a population of millions. The soldier ants of this species are distinguished by their impressive size: the carrying capacity of the soldier ant is hundreds of times higher than that of the worker ant. However, the soldiers cannot perform a large amount of work for the colony: they are too massive, their maintenance is expensive for the population, and the exact purpose has not yet been fully figured out by biologists.

However, when biologists began to observe regular attacks by nomadic ants on leaf-cutting ant colonies, they noticed how leaf-cutting ants were responding to these invasions. Thousands of huge leaf cutters are sent to the front line, where they must try to repel the attack of nomadic ants. In most cases, their efforts are unsuccessful, and ultimately the nomadic ants will still break through the line of defense. However, it can be assumed that it is precisely the protection against nomadic ants that is the reason for the existence of soldier leaf cutters. This observation supports the theory that fighting or fighting other ants is an important aspect of ant evolution.

If you take a closer look at how other ants respond to the attacks of nomadic ants, you can distinguish a wide range of reactions: some species of ants try to fight off, others begin to panic, barely seeing the first soldiers of nomadic ants, and rush to save the nest. They usually evacuate the offspring and try to move as far as possible. Feeling safe, they stop and bide their time. After the satiated nomadic ants leave the devastated colony, the victims of the attack can return home.

Modern ant research

Biological characteristics of invasive ant species are of current interest. Scientists have begun to realize that knowing whether a colony is getting involved in collisions helps us learn more about biological invasions and their possible negative consequences. Certain species of invasive ants are causing environmental problems on a global scale - not only for humans, but also for the compromised ecosystems of their invasion sites. Given that they are wiping endangered species off the face of the earth and their behavior contributing to habitat restructuring, they can have dire effects on the environment.

They also pose a problem for humans: these ants climb into food, some species give off an unpleasant odor, and cause disease. Understanding ant wars may be the key to uncovering a trait that invites invasive ant species to behave like this. Perhaps this discovery will help us develop a reaction to ant demarches, or even predict when something like this will happen again. Therefore, today there is a huge amount of research on ant aggression and ant wars, which is expected to provide an answer to the question of biological invasions.

The ant picks up the nectar of the aphids

It's a good idea to take a closer look at the species of animals that directly benefit from ant wars. In the colonies of many subspecies of ants, representatives of other species live, called myrmecophiles. These representatives of the animal world get their food mainly from the ant colony. Usually we are talking about parasites, but their negative impact on the life of the colony, as a rule, is minimal. Myrmecophiles develop the ability to hide from ants. The mechanism of recognition of fellow tribesmen adopted in the colony does not apply to them, but they somehow bypass it. And species, whose fate is linked to the fate of the ant colony in evolutionary terms, demonstrate a keen interest in the outcome of ant wars. In other words, if the colony is ruined, they too have a hard time. However, at the moment, scientists do not have information about the direct participation of myrmecophiles in battles, although the idea is not bad.

We are currently working in two directions. First, we study the evolution of the ant brain and try to understand how the nervous system responds to various environmental conditions, whether it predetermines the social roles and body sizes of ants. Second, we are interested in understanding how nomadic ants can be used to study temperature fluctuations and, possibly, the impact of climate change on the genetics and psychology of wildlife. We see nomadic ants as an excellent model for research, in part because members of the tropical nomadic ant species can withstand a wide range of temperatures: identical subspecies were exposed to very high temperatures in low-lying areas and very cold in the mountains in the course of research.

Open questions

From a flurry of scientific articles that appeared in 2015, we learned that the structure of the ant brain has undergone significant changes in recent years, in particular, in the aspect of the transformation of a species from an entomophage into social beings. This change theoretically confirms the assumption that, having become a social being, a representative of the species does not need the same high level of development of his brain and cognitive activity, since now he can share information and integrate with other representatives of his subspecies - almost the same as if neural connections could be brought to the group level. This discovery was a real breakthrough; it is necessary to analyze similar trends in representatives of other species in order to understand whether this applies to all representatives of the fauna. This is important, because if you look at the representatives of the class of vertebrates - mammals, birds, fish, most of them basically show the exact opposite tendency. In other words, if your species becomes more socialized, brain activity also increases; insects, on the other hand, show the exact opposite relationship. There are many exciting discoveries in this line of research.

Questions about megacolonies remain open. It is not known how deep their integration is. Perhaps everything is limited to the local level, and they exchange information only over short distances. It is interesting to imagine deeply integrated colonies, although they are unlikely to be able to exchange information over long distances. Not a bad idea for a science fiction novel, though.