The Perumpanarruppatai, a poetic work in Tamil from the Sangam period between 300 BCE and 100 CE, has a stanza that compares freshly sprouting rice grain with the termites found in their mounds. These lines sprang to my mind when I first saw the television commercial for Century Ply, a company that manufactures plywoods – fat, padded termite bodies on the insides of a kitchen cupboard. Living in a 175-year-old house made of mud and wood, termites and cockroaches are a familiar sight. Every time I see ads for insect repellents which tell the public how good their products are, I marvel at how little humans know about the creatures we share space with.
Perish the thought that termites are fat or ugly. The only fat, obese termite is the queen, when she is filled with eggs. The rank and file of termites who feed, clean and take care of her, working to expand the colony, are smart, lean and mean, despite the fact that termites feed on a carbo-rich diet of wood, soil, grass, litter and even animal dung. Concrete is no barrier either, a small crack is all they need to start occupying space. The greatest secret to their success, is their choice of food: they exploit an exclusive and abundant food source, a biomolecule called lignocellulose, which no other creature, not even other insects, can eat. Since lignocellulose does not degrade easily, termites can access it from living plants and dead wood or soil too.
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To consider termites plunderers is unfair. They are the most important animals in a forest ecosystem, single-handedly decomposing 40% to 100% of the decaying wood and thereby enriching the soil. Subterranean termites, which are among the ones that bothers us humans, serve us well too. As they tunnel through the soil, building swarming tubes to forage for food, they increase the soil’s porosity, facilitating greater percolation of water. Termites are known to dig as deep as over 100 feet in search of water to maintain the humidity of their mounds. As early as 500 CE, Indian astronomer Varahamihira wrote in the Brihat-Samhita that termite mounds were indicators of ground water and mineral deposits.
Not all termites build those iconic mounds. Many reside in carton nests. Some are open-air processional column termites, foraging on tree trunks or living off leaf litter and nesting on tree branches or decaying roots. Carton or mounds – over a period of 55 million years of existence – termites have learnt how to manage their constructions efficiently, keeping them well ventilated and maintaining the temperatures needed for their survival.
The open-air foragers nest on tree branches or decaying roots. To avoid predation by ants and other arthropods, termites squirt sticky fluids onto foraging surfaces. Spiders or ants who venture too close get stuck and are also affected by these chemicals. If they move, the workers will bite or hold them down, until other termite-soldiers can come and spray some some more before finishing them off. The squirting apparatus of the termite-soldier is precise and efficient.
The carton nests of termites from the sub-family, Nasutitermitinae, can be seen at the Kanyakumari wildlife sanctuary. The Kani tribe feed these termites to their chickens. In the desert ecosystem, termite species live on the dung of hoofed mammals, besides feeding on leaf litter.
Every time the termite feeds or builds, it modifies the habitat for the benefit of other organisms including humans. This might explain why termite mounds, mistakenly called ant hills, are worshipped – the clay from termite mounds was used to build Vedic fire altars and included in the Rajasuya yagna performed by kings.
Termite soldiers guarding the nest. Credit: Geetha Iyer
Termite soldiers guarding the nest. Credit: Geetha Iyer
What makes termites so successful? Their food source, caste system and their ability to produce large colonies. There is no realistic account of how large a subterranean colony of termites can be because most data is extrapolated from limited studies. A termite colony has a king and queen who pair for life, mating repeatedly to build their vast empire. Other social insects do not pair for life. Apart from workers and soldiers, the colony also has secondary reproductives capable of laying eggs and expanding their colony. Should the king or the queen die, the secondaries step into their roles, yet another reason for the dominance of termites. Sometimes even when the queen is active, the secondary reproductives produce eggs. The colony prospers and humans despair.
Alates or winged termites emerge during the monsoon to establish new colonies. A tiny crack in the wall or floor is enough for them to enter an underground world. Alates die if they do not find a mate. In rural India they are gathered to be eaten, the fat, juicy termite queen in particular, is considered nutritious and a delicacy. It is only the alates who see well – the workers and soldiers are either blind or have poor vision. The way termites communicate can help humans fine-tune communication technology. If you watch a procession of termites in the forest, you can actually hear them move – they do so by hitting their head on the soil. The sound is so rhythmic, that in the silence of a forest it sounds like a march-past.
Termite alate. Credit: Geetha Iyer
Termite alate. Credit: Geetha Iyer
Termites process cellulose and lignin by the exclusive army of microbes found nowhere but in the gut of a termite. Evolutionary scientists have hailed the diversity of termite-gut microbes as a sterling example of co-evolution. These microbes are acquired through a unique process called anal trophallaxis – or anal to mouth feeding. Every time a termite moults, it sheds its outer skin as well as its gut lining, where the microbes reside. Newly moulted termites feed from the delicious anal fluids secreted by other adult termites to re-inoculate their gut. The workers must eat constantly, the soldiers cannot eat as their mandibles (a pair of appendages near the mouth) are modified for defence. They and the reproductive castes obtain their nutrients from the workers through oral or anal trophallaxis.
Anal feeding is a common practice in lower groups of termites. The more evolved ones from the family Termitidae cultivate a variety of fungi in their nests. These fungi grow on the faeces of the termite and in turn provide food for them. Termites believe in sustainable living – they re-cycle or consume everything from dead nest mates, moults to excreta. Faeces are used to build quarantines, construct swarming and often gravity-defying exploratory tubes. These tubes provide moisture for subterranean termites when they forage outside their nests.
Termites have also inspired African architect Mick Pearce – two buildings designed by him, the Eastgate Centre in Harare, Zimbabwe, and the Council House in Melbourne are a testimony to what one can learn from these tiny, visually challenged yet fiendishly clever and socially adaptive insects.