Communication in Ants

Introduction

Social insects are more advantageous with respect to solitary insects over solitary insects. Many individuals in the colony increase systematic functioning, organised and efficient working, sharing information through specialised communication about the food resources. It helps in the foraging of the colony, in many cases retaining the memory of previous reward source and select location of profitability.

Communication in Ants

Foraging communication of social insects has been a subject of study for long. In 1880s, Victorian John Lubbock found that ants use odour for trail networking and foraging. Wassman, his contemporary believed that ants have a sophisticated language encoding by antennal tapping similar to Morse code. Karl von Frisch won Noble Prize in 1973 for discovery of waggle dance as the method of communication for direction of travel and distance of food sources.

Ant species were investigated and found that they secrete chemicals called ‘pheromones’ by different glands. In 1962, Wilson published in his research that pheromone trails provide a positive and negative feedback response to organise workers for foraging. A colony of ants forms trail of pheromones and returns to nest with food collection, trail gains strength as more and more workers get involved in this network. The trail becomes weak when food sources are decayed.

Ants specialised in this function use multiple pheromone trails secreted by more than one gland which provides a long-term memory of the reward source and signals no entry regions of unrewarding or less food availability.

Types of Communication in Ants

Foraging Communication

Communication is favoured by natural selection if it helps the nest mate for foraging efficiently. If worker A helps worker B to collect more food, this is as good as A collecting food for herself, because the food will be fed to the larvae of the same nest. In some cases, many social insects have no foraging information to share in desert ants, which collect dead insects, there is little or no information to share with their nest mates.

Communication is very useful when food resources are larger in size, require multiple foragers to exploit and feed on them. Renewable feeding sites like a site inhabited by a group of aphids secreting honeydew or flower patches can be good information for communication to nest mates. Most ant species are dependent on transient food sources, which is a dynamic and competitive environment, providing an advantage to the colony for quickly acquiring the best food.

Ants employ a variety of communication methods for helping nestmates in foraging, simplest is tandem running, where a forager leads a group of recruited workers. The recruited follows through physical contact or pheromone signals of the leader. Use of pheromone trails for movement is known as mass foraging. This occurs through broadcasting the guidance information to all potential foragers in the form of trail marks with varying amounts of pheromones.

Multiple Pheromone Trails

Trail pheromones can be secreted for different glands like Dufour’s gland, poison gland, glands on thorax, anal glands, and glands on feet. Use of pheromone secretions for trail networking by a single ant species is complex, compared to a single pheromone trail.

A trail following memory can be created due to multi-pheromone effect in multiple forages and can return to the resource site for exploitation. Non-volatile pheromone can enhance long-term memory, while volatile pheromones only allow to make rapid food choices and can quickly forget resource locations. Raiding army ants are known to use rapid-effect, short-lived trails to coordinate their lightning raids.

Sometimes pheromones are secreted from both poison and pygidial glands. While attacking prey, the ant gets detached from the trail and pheromone of pygidial gland guides it back to the trail, helping in spatial organisation and systematic unidirectional movement.

In Pharaoh ants, common in human habitats, both short-lived and long-lived pheromone trails are found. Short-lived trails are used to guide foragers to the food source, while long-lived trail help to organise foraging.

Caste-Specific Communication

Division of labour is a remarkable characteristic of social insects. Researches show that individual specializations of ants are present in relation to pheromone trails. In Pharaoh ants, workers which get in touch with the food substrate can detect long-lived trail pheromones. These ants, called pathfinders, are specialised, sub-castes of the foragers’ group and help to re-establish existing trails, converting long term memory into an easily detectable signal. These forager ants are of same size, but in some cases, trail pheromone differences involve different ant sizes.

In Pheidole embolopyx, minor workers are specialists in laying trails from poison glands, both major and minor workers follow pheromone trails of foraging. Major workers do not secrete pheromones, but help in transporting and defending food.

Minor workers bite legs of competitors, while majors attack the head. Atta leafcutter ants secrete alarm pheromones to frighten predators. Different size of leafcutter secretes different blends of alarm pheromones, but worker castes respond differently to blends of other workers.

Multimodal Communication

Apart from chemical communication, foraging ants also use other modalities to communicate and a combination of signals of different modalities to promote organization of the foraging system, and in defence. Leafcutter ants form defence foraging columns while transporting leaves back to the nest along pheromone trails, through substrate-borne vibration or direct contact. Direct contacts are ritualised movements of communication like dancing, waggling, and jerking. Most common form of tactile communication is mutual antennation, very frequently observed in ants passing in opposite directions of a trail.

Use of sounds can also use to create alarm, like Camponotus senex living in large arboreal nests on slight physical disturbance or by carbon dioxide, produce alarm response by drumming their abdomens upon the nest substrate. This alarm stimulates other ants to follow the group throughout the entire length of the nest.

To communicate a repeated message, multiple pheromones, contacts, displays, and sounds are used in combination like in Aphaenogaster albisetosus control recruitment pheromone by rubbing their abdomen tergites to make a sound. When individual workers locate large prey like a dead insect, it releases pheromones from poison gland and makes audible sounds to attract other workers in the location, further pheromone is released by other workers and a feedback loop is created to rapid trail recruitment to the location of prey.

Conclusion

Ants are social insects and possess various ways of communication. A colony of ants consists of thousands to millions of ants living in a single colony; therefore, it is essential for a coordinated system to find its meal and protect itself from intruders and predators. Communication, therefore, serves as a vital tool for exchanging information in a synchronised manner to reduce uncertainty and solve the nutritional needs of the colony.

FAQs

Qns 1. Do ants communicate with each other?

Ans. Yes, they communicate through the secretion of chemicals.

Qns 2. How long can ants communicate?

Ans. They can communicate through trail of pheromones of more than one-metre length.

Qns 3. What do ants communicate with each other?

Ans. Ants communicate about food locations to each other.