Exploration on Ants and their social benefits for surviving the world
Written by: Kausthubh S, Sanjana Subramanya, Dr. Praveen Kumar Gupta
A general ant colony
An ant colony refers to the social rules ants follow to organise themselves and work. Each colony contains thousands of ants and are located underground most of the time. In terms of an ant society, there are four different types of ants. A colony can be termed as a superorganism with multiple members each having a role of their own to play to make the colony survive as a single unit.
The queen ant, the founder and leader of the colony is responsible for populating the colony by laying thousands of eggs. They have wings, are bigger in size than the other type of ants found in the colony and their chamber is located deep inside the colony in order to protect them from predators. Their average lifespan can range from 10-15 years but in case of some species it can go up to 30 years.
The drones are the winged male ants present in the colony and their only function is to mate with the queen ant, after which they die. The queen ant stores the sperm in its pouch and fertilizes its eggs. All the fertilised eggs develop into male ants and the unfertilised ones develop into female worker ants.
Worker ants have various functions. They are mostly responsible for building and maintaining their nest. Some workers tend to the eggs and help in their development. These do not mostly leave the nest. The others leave the nest (as shown in in Figure 1) to forage for food.
The queen also lays eggs that produce males and females termed as alates which leave the nest in swarm to build up a new colony.
Working and survival of an ant colony
During the breeding season, all winged drones and queens from different colonies meet at a common location called the breeding ground. After mating, the queen ants settle down discarding off their wings while the drones die. Each queen ant fertilises some of its eggs which further develop into drones while the unfertilised ones develop into worker ants. These worker ants help in building up a structured, organised colony. Each worker ant communicates with one another through touch, sound and other chemical stimuli helping to signal the presence of a predator, death of a fellow worker ant or even when the queen is nearing the end of its reproductive life. The colony workers have the ability to explore a large area without any predetermined plan. This is achieved by changing their moving patterns according to individual interaction, sensing each other by connecting their antennas together slightly. More the ant population, more often can these interactions take place ensuring an easier exploration of a large area due to an increase in randomness thus ensuring a more thorough exploration. During foraging, some species of ants follow a method called recruitment. When a worker ant finds some food, it will return back to the colony with it and while traveling back, it marks the path it takes with a specific chemical scent. This guides the other worker ants to reach the location of the food with ease to bring back more to the colony. Each worker ant produces that chemical scent to guide the next one. After the food source has been exhausted, the ants stop producing the scent hence making it gradually disappear.
Social living confers several benefits to ants even though individuals may be genetically identical. Group living prompts insects to specialize in certain tasks, resulting in systematic division of labour which in turn induces increased stability.
Task allocation in ant colonies is built on networks of interactions. An ant’s role can vary with changing conditions, depending on the colony’s requirements and is heavily dependent on effective communication. Ants rely on chemical communication for this and an aggregate of these simple interactions enables colonies to alter the number of ants performing a particular task in response to varying conditions. For example, it has been observed in harvester ants that the colony adjusts the number of individuals out foraging in accordance to the amount of food available. A departing forager does not head outside the nest until it encounters enough foragers returning with food. When food is abundant, more and more foragers return to the nest quickly, triggering more foraging, which prompts ants previously performing other tasks to switch to foraging.
Group living also provides additional benefits like increased protection against predators, higher efficiency in foraging, increased reproductive rates and greater survival rates. However, all this comes at the cost of higher risks of transmission of parasitic infections by bacteria, fungi, viruses etc. To combat this problem, eusocial insects like ants have developed certain colony level defences against pathogens. These defences can drastically reduce infection and improve the survival rate of the colony and is collectively termed as social immunity and encompasses a number of mechanisms including- providing sanitary care for infected members, killing infested brood (as shown in Figure 2), eliminating corpses and waste material and incorporating antimicrobial substances into their nests.
For example, when a virulent, entomopathogenic fungus like Metarhizium anisopliae infects an ant colony, healthy individuals allogroom infected members in order to remove fungal spores before they have a chance to proliferate. While most of the spores licked off the affected individual’s body are killed off in the intrabuccal pockets of the ants’ mouths, healthy ants may end up with a few fungal spores on their bodies which can usually be eliminated by individual immune responses as they are comparatively tiny doses of the fungus. These low-level infections are beneficial as they build up resistance in ants and result in a more effective group response to a pathogen it has already been exposed to.
The random movements of ants belonging to a colony exhibiting social behaviour during foraging was experimentally studied and determined by letting ants enter empty spaces of various orientations. This has found applications in computer modeling to acquire feasible solutions from decentralised elements with random exchange of simple information. This has been known to help in solving many types of problems like finding the shortest route to take in an area. It also helps in scheduling computing tasks to be executed in the most optimal way. The same application can be found in designing robots to explore a minefield. The ecological success of ants has largely been attributed to the evolutionary transition from solitary life to group living and their societies have thrived for over 120 million years all of which point to radical possibilities for mankind.
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