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Wildlife

Amazing ants

Print edition : Mar 11, 2022 T+T-
FL11pfArmy-antAenictus-artipusPhoto-by-K-Sadheeskumar

Army ants (Aenictus artipus) are highly effective predators, armed as they are with large mandibles and a painful sting.

FL11pfWeaver-AntOecophylla-smaragdinaPhoto-by-R-Bhanumathi1

The weaver ant (Oecophylla smaragdina) acts as a keystone predator.

FL11pfAnts-congregationPhoto-by-R-Bhanumathi

The social organisation of ants and their ability to adapt to different environments enabled them to colonise the entire earth millions of years ago.

FL11pfSugar-antCamponotus-consobrinusPhoto-by-K-Sadheeskumar

Sugar ant (Camponotus consobrinus), a species native to Australia.

FL11pfFire-antSolenopsis-geminatePhoto-by-K-Sadheeskumar-2

Fire ant (Solenopsis geminate).

FL11pfLeptogenys-processionalisPhoto-by-K-Sadheeskumar

Leptogenys processionalis, a species of ant of the subfamily Ponerinae.

FL11pfPheidole-spPhoto-by-K-Sadheeskumar

Pheidole, a widespread and ecologically dominant genus of ants that includes more than 1,000 species.

FL11pfSingapore-AntTrichomyrmex-destructorPhoto-by-K-Sadheeskumar-2

Singapore ant (Trichomyrmex destructor).

FL11pfSpiny-AntPolyrhachis-bihamataPhoto-by-R-Bhanumathi

Spiny ant (Polyrhachis bihamata).

FL11pfBothroponera-spPhoto-by-K-Sadheeskumar

A species of ant in the Bothroponera genus.

FL11pfCarpenter-AntCamponotus-pennsylvanicusPhoto-by-R-Bhanumathi1

Carpenter ant (Camponotus pennsylvanicus).

FL11pfAphaenogaster-SpPhoto-by-K-Sadheeskumar

Aphaenogaster, a genus of ants that are carnivorous and collect dead insects.

FL11pfGrassland-antCamponotus-compressus-Photo-by-K-Sadheeskumar-4

Grassland ant (Camponotus compressus), a groundnesting species of ant found in India and Southeast Asia.

FL11pfSingapore-AntTrichomyrmex-destructor-Photo-by-K-Sadheeskumar-1

Singapore ants (Trichomyrmex destructor) are a pest species in urban areas, known for causing costly damage to structures, vehicles and electronic devices with their chewing activity.

FL11pfGhost-antTapinoma-melanocephalumPhoto-by-K-Sadheeskumar

Ghost ants (Tapinoma melanocephalum).

FL11pfCrematogaster-brunnea-contemtaPhoto-by-K-Sadheeskumar

The Crematogaster (brunnea contemta) is known to make its nests on trees.

FL11pfGrassland-antCamponotus-compressusPhoto-by-K-Sadheeskumar-3

The grassland ant (Camponotus compressus) is one of the many species which tends insects like aphids and tree hoppers.

FL11pfMeranoplus-bicolorPhoto-by-K-Sadheeskumar

Meranoplus bicolor, an ant species found in many Asian countries, where its habitats range from open grasslands to open-canopy forests.

FL11pfPrenolepis-Sp-Photo-by-K-Sadheeskumar

Prenolepis a relatively small clade of formicine ants found in southern China and southeastern Asia.

FL11pfPolyrhachis-rastellaPhoto-by-K-Sadheeskumar

Polyrhachis rastella, a species in Formicinae, a subfamily of Formicidae.

FL11pfTetramorium-spPhoto-by-K-Sadheeskumar

Tetramorium, also known as pavement ants.

Omnipresent, with a unique social organisation and the ability to adapt to different environments, ants have often been compared to human society. An excellent candidate for insect studies, ants greatly outnumber all other animals on the planet, including human beings.

ANTS, like bees and wasps, belong to the order Hymenoptera, within which they form a separate family, Formicidae. Entomologists, like their zoologist colleagues, like to draw up genealogical trees so as to classify animals by similarities, and so they have divided Formicidae into subfamilies (about 20), genera (between 296 and 358) and species. Around 12,467 species of ants have been discovered so far. These numbers will probably increase soon, given the rapidity with which myrmecologists (ant specialists) are adding to discoveries already made.

Since time immemorial, humans have been fascinated and intrigued by ants. And yet, at first glance, there is nothing particularly attractive about these tiny creatures. Unlike butterflies, they do not have wings with vivid colour patterns; they cannot boast the iridescent wing cases seen on many beetles. Nor do they produce things that humans like to eat or wear, such as honey or silk. Unlike crickets or cicadas, they do not chirp or sing; unlike bees, they do not dance.

They do, however, have other characteristics which are much more remarkable. For one, their social arrangements are quite extraordinary, almost unique among living creatures, and have often been compared to human society. William Morton Wheeler, the founder of American myrmecology, wrote in Ants (1910): “The resemblances between men and ants are so very conspicuous that they were noted even by aboriginal thinkers.” Likewise, ants are not only efficient but also hard-working and thrifty, qualities which seem like a good reason to see them as virtuous role models.

Historical references

In 1000 BCE, King Solomon hailed ants as models of wisdom, as noted in the Old Testament: “Go to the ant, thou sluggard; consider her ways, and be wise: Which having no guide, overseer, or ruler, provide her meat in the summer, and gather her food in the harvest” (Proverbs 6:6–8). Centuries later, La Fontaine’s fable “The Cicada and the Ant” endorsed the same qualities. Ants are also mentioned in the Quran, which presents them as a highly developed race of beings, and in the Talmud, again as synonymous with honesty and virtue.

Greek philosophers, such as Aristotle, Plato and Plutarch, praised these social insects as wise and clever. The Roman naturalist Pliny the Elder devoted a whole chapter of his Historia Naturalis to ants, expatiating on their bravery and strength. He even mentions ants as big as dogs found in India and Ethiopia that stood guard outside gold mines and killed any man who attempted to make off with the precious metal.

These accounts are, of course, closer to fiction than to fact, but they do attest to the human appeal of ants, as well as to the fears they could engender. They also reveal an awareness of how aggressive the insects could become. But what was uppermost in the ancient world’s appreciation of ants was how they could communicate with one another, devise their division of labour, and construct nests of such architectural complexity, which the natural historian Aelian compared to palatial residences.

The Dogon people of West Africa saw ants as the wives of the god Amma and the mothers of the first humans. Ants were also central to traditional rituals, such as among the Wayana-Apalai peoples of Brazil, Surinam and French Guyana, where a boy reaching puberty had to demonstrate that he was worthy of adult status by wearing a sling full of fire ants round his torso or tied to his back, thus proving his courage and endurance.

In recent times, ants appear prominently in popular culture, from works of science fiction to novels, children’s books, comics and video games. Toy manufacturers have taken to selling ant aquariums, so to speak, in which water is replaced by a nutritious gel, thus enabling children to have ant colonies of their own. After goldfish and hamsters, it is now the turn of ants to be household pets.

Following in the footsteps of illustrious naturalists such as Rene Antoine Ferchault de Reaumur and William Gould, the entomologists and myrmecologists of today are enthusiastic investigators of the lives and ways of these social insects. Their research has led them into a world that is rich and full of surprises and one that is, even after decades of observation, still full of unsolved mysteries. What is the secret of the huge ecological success of ants? How did their sociality develop? What is their social organisation like in different species? The universe of the ant, when subjected to the most advanced methods of scientific investigation and observed with the magnification afforded by genetics and molecular biology, can be seen in a new light and now reveals a range of ways of life that for many years went unrecognised.

It has long been known that ants were inclined to live in intricately organised societies made up of individuals that cooperated, communicated and divided up daily tasks. Now we also know that they have impressive abilities in finding their way around and amazing ingenuity when it comes to building their nests, finding supplies or exploiting other members of the animal kingdom. We can see, too, that they are capable of aggression and violence, which can disturb the apparent peace of their colonies and embroil them in fratricidal or matricidal strife. Studies of the sexual arrangements of ants have revealed their strange ways of reproduction and the remarkable stratagems they employ to increase the numbers of copies of genes transferred to their descendants. In this area, as in many others, they display a marked originality. They never cease to amaze those who study them.

Ants are nothing if not ubiquitous. Venture a few steps into any woodland and you will find an ant nest, with all its denizens busily moving about. In springtime, and more so in summer, crumbs of food or grains of sugar left out in the open are soon visited by a long procession of tiny black creatures, scurrying along one after the other, intent on making off with an unexpected hoard of nourishment. Ants, in all their minuteness and their teeming numbers, are just part of the background, familiar, natural, taken for granted. Yet as soon as you start to look more closely, ants turn out to be exceptional in many ways. Their social organisation and their ability to adapt to different environments enabled them to colonise the entire earth tens of millions of years ago. They greatly outnumber all other animals on the planet, including humans.

Ants have been recognised as an excellent candidate for insect studies. The insect order Hymenoptera (ants, bees, wasps, and their kin) is receiving attention because it is hyper-diverse and its biodiversity is indicated by the lack of a “unifying common name”. In terms of numbers, dominance and ecological importance, Hymenoptera are fundamentally significant. The ant family (Formicidae) alone in this order can be used to exemplify the importance of insects and biodiversity.

Ants strongly influence the functionality of ecosystems. They dominate by their massive biomass, manipulate species composition, influence trophic interactions, possess numerous mutualistic and symbiotic relationships, and shape both the abiotic (for example, moving soil) and biotic (for example, plant-ant mosaics) matrix of community interactions.

The family Formicidae contains 21 subfamilies, 358 genera and more than 11,000 species worldwide. In India, there are 108 genera and 847 species of ants reported so far. Ants are well suited for studies in taxonomy, biodiversity, community composition and biogeography. To accurately assess biodiversity and community dynamics, focal taxa require certain criteria such as ecological significance, diversity and ease of collection. In the past, these efforts were focussed mostly on birds, vascular plants, and mammals. A number of recent studies have shifted the focus to include invertebrates such as beetles, butterflies, ants and aquatic macro-invertebrates. Ants are noted for their proportionally large biomass in ecosystems, making them an important and dominant component of all terrestrial habitats. They also fill numerous niches and often act as “keystone species” and also as predator, mutualist and resource species.

Keystone species

Weaver ants (Oecophylla) act as keystone predators. In the role of keystone mutualist, ants are needed by some plants for protection, nutrient recycling and dispersal of pollen and seeds (also known as myrmecochory or seed dispersal by ants).

Ants are keystone resource species as well; they influence soil structure by turning earth and transporting organic material into their nest, acting to fertilise soil. In addition to being a food resource for other organisms (from other arthropods to mammals that specialise in eating ants), ants are associated with numerous organisms, including vertebrates, that require them for their survival. Such interaction can be seen in army ants and ant birds, which follow the raiding trails of army ants. One other example is the location of the nests of some neotropical birds in ant-occupied trees. In addition to high diversity, ants possess a quasi-stable taxonomic and systematic status, which creates a situation where identification is assessable and widely understood.

A study that examines the biodiversity of ants in India is overdue. A better understanding of the current state of community composition across habitats in India needs to be developed. The culture and study of ants in the laboratory is a relatively simple operation. Most insectivorous ant species thrive on this diet when fed three times weekly along with fragments of freshly killed insects, such as mealworms, cockroaches and crickets offered in small quantities. However, the food habits of ants are unknown.

Thoroughly understanding ecosystems has become extremely important as humankind’s practices have led to a degradation in environmental conditions. The mass decline of species diversity causes ecological instability, which directly affects all life on earth. Fortunately, considerable research is under way to investigate patterns of biodiversity in the context of the ongoing mass extinction. One emerging method is that of rapid assessments; these studies take a picture of local diversity. Such studies often produce regional lists that not only aid in further research but also are beneficial to local communities by raising local awareness.

Once a common practice in biology, the creation of regional lists for species is not a common practice today, yet the need is apparent. A significant study would be the assessment of biodiversity, community composition, biogeography and other basic investigation of ecology of a regional biota. Such a study would grant researchers a baseline from which to begin more detailed studies. So, those who specialise in this field have their work cut out for them. It will entail locating, naming and classifying the yet undiscovered species, many of which will probably be found in the tropics, where many regions still have much to divulge about the richness of their ant life. Entomologists are convinced that, even in more temperate regions of the world and despite their own ant-like endeavours, several species of ants have still escaped detection.

One of the most fundamental areas in biology is the study of a species; once one knows what something is, the door to understanding it opens. Investigations into taxonomy, phylogenetics, behaviour and natural history have been afforded to relatively few taxa. Even with many scientists studying invertebrates, limited research coverage has been accomplished. The limited treatment may be an artefact of the diversity of these groups. For example, the class Mammalia has about 4,000 species, and the phylum Ctenophora/Cnidaria has about 9,000 species, but the family Formicidae has nearly three times as many species as mammals. The limited amount of research on insects is understandable with such a hyper-diverse group, and further study is needed to understand the broader themes in biological research such as ecology, evolution, as well as medical research (pharmaceuticals), the establishment of what an organism is, what it does, and how it is related to other biota.

Ants are omnipresent, more so than any other animal known to science. We do not know how many of them there are on the planet, as nobody has ever been able to actually tot up their numbers. The importance of knowing what species exist, and in what numbers, is one of the most basic questions in biology and will lead to many more discoveries.

This article is dedicated to E.O. Wilson, the myrmecologist and “Darwin’s natural heir” who passed away on December 26, 2021.

Dr Vaithianathan Kannan is a wildlife biologist with the Mudumalai Tiger Reserve.

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