An Introduction to Termites
Termites are insects belonging to the Isoptera order. They feed on cellulose, and the social structure of their groups is highly similar to that of ants and bees. These insects, however, have evolved independently. Despite being quite different from ants, termites also enjoy the name of white ants, entirely due to their appearance. After conducting several phylogenetic studies, scientists found that the closest relative of termites is the cockroach and not the ant. For this reason, it is also not uncommon to group these insects in the order Dictyoptera. This classification puts them in the same order as the mantids. In this article, we will discuss several topics which are relevant to the study of termites. By the end of the article, you will have a fair idea about the natural habitats, importance, and natural history of termites. We will also discuss two aspects that make termites primarily well known, namely, the remarkable termite colonies and their elaborate social structures.
Distribution and Abundance of Termite Insect
We have several species of termites, in particular, over 2700 species. These insects are spread across the world but reach their highest numbers in terms of abundance and variety of species in tropical rainforests. If we talk about North America, we find termites inhabiting both the Pacific Coast as well as the Atlantic Coast. On the Pacific Coast, the Zootermopsis species of termites inhabit areas as far up north as Vancouver, British Columbia. Meanwhile, the Reticulitermes are spread across Maine and eastern Canada along the Atlantic Coast.
If we move to Europe, Reticulitermes lucifugus inhabit regions up to the Atlantic Coast of France, but a species introduced by humans, Reticulitermes flavipes, occurs in Hamburg, Germany as well. The natural distribution of termites in Europe tends to accumulate in the Mediterranean countries, and so termites are not naturally abundant in Great Britain, Scandinavia, Switzerland, Germany, or Northern Russia.
As we move to the eastern regions of the world, we find Reticulitermes speratus occupying areas as far north as South Korea and Japan. Termites also naturally occupy the Cape regions of South Africa, Australia, New Zealand, and Tasmania.
All termite species found in different parts of the world are not naturally occurring. Many of them are transported from their native habitats and introduced by human beings into different parts of the world. Two species of termites, namely Cryptotermes and Coptotermes got transported unintentionally to different parts of the world in wooden items like shipping timbers, boat items, etc. The species of termites known as Cryptotermes are primarily wood termites and they can survive in dry wood without moisture for long periods. Due to this adaptation, they can usually be transported across long distances. Other species such as those of Coptotermes need moisture and cannot live through long dry spells.
A species that is naturally abundant in Japan, Taiwan, and South China, namely Coptotermes formosanus has been manually introduced across the world in places such as Sri Lanka, the Pacific Islands, Hawaii, South Africa, and some parts of the southern United States. An interesting fact about C. formosanus is that it can survive without direct contact with soil as long as it has access to a source of moisture.
We have yet another story of termites being shipped across seas in wooden containers of decorative potted plants. These termites are a species native to North America, particularly the United States, known as Reticulitermes flavipes. R. flavipes were found in the hothouses of the Royal Palace in Vienna even before they were discovered in the United States.
Importance of Termites
The termite insect has a great significance in the world of humans. Termites can be excessively destructive as they often destroy and demolish wooden structures and vegetation that are valuable to human beings. Termite infestations are common in houses across the world, and these insects are a serious threat as pests. Generally, it is the introduced species that contribute to the problem of home infestation, because these species are not that well equipped with the natural environment and habitat of their new homes. Some termites feed primarily on plants and vegetable matter, and these can pose a huge threat to agriculture. However, termites do help farmers in a way. These insects can digest and break down cellulose in plants into substances that can be used to support the growth of new plants.
Only a small percentage of the roughly 2700 species of termites get categorized as pests, but these can cause heavy losses and damages. To control the infestation of these insects, it is important to know whether the species is subterranean or wood-dwelling, as preventive methods vary in the two cases.
Subterranean termites require both soil and moisture to survive and generally occupy manmade structures. Insecticides are widely used to control the attack of these insects. There are also guidelines for the monitoring of important wooden structures. If a group of termites is found in the perimeter of a building then we use bait to attract them and then they feed on cellulose-containing organisms with a chitin inhibitor in them. This disrupts the normal functioning of the exoskeleton of the worker termites and eventually, the colony dies. There are also a lot of construction guidelines in place, meant to prevent the entry of termites into wooden structures. Removing scrap pieces of wood from buildings is also an effective way to control termite colonies.
Dry-wood termites inhabit wooden structures and do not enter through the foundations. For this reason, they are more difficult to control. Using chemically treated wood in construction is one of the ways to deal with these termites. Paints and other substances are used to cover up and seal cracks in the wood. Fumigation and the use of insecticides are also other effective methods to control dry-wood termites.
Termite colonies are well known for their detailed and structured design. They have a well-built organization based on each member's type, function, and abilities. The three main divisions in the termite colony are reproductive, soldier, and worker castes. Soldiers and workers are sterile and hence they cannot reproduce. They can be either male or female. The reproductive group of termites is of two kinds, namely primary and secondary or supplementary.
Humans have not figured out how the classification into different castes takes place in a termite colony. According to studies, a nymph has an equal probability of growing into any one of the three types.
Another interesting phenomenon of termite societies is that the number of each type of termite is closely monitored. There are usually a couple of reproductive members and a very specific ratio of workers, soldiers, and nymphs. Surprisingly, if the colony loses any members, an equal number of nymphs develop themselves to fill those roles. On the contrary, if the colony gets overpopulated, selective cannibalism takes place and the numbers are curbed.
Chemical substances such as hormones and pheromones are the driving forces of the differentiation of castes. Certain hormones produced by a particular group of termites, say, soldiers, are passed onto the other members through food, by a process called trophallaxis. These hormones inhibit the growth of soldiers in the other members to maintain the ratio of each group. This theory has been proved to be true through several experiments carried out on Zootermopsis and Kalotermes termites.
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Swarming is the phenomenon of a termite colony dispersing due to the growth of adult termites with wings, known as alates. This is typically a seasonal growth and leads to the formation of new colonies. After adults develop wings, they occupy the periphery of their colonies for certain amounts of time until they can fly off. These flights are generally associated with several seasonal, climatic, and weather conditions.
The colonies prepared in advance for the departure of the alates even before their emergence. They build exit routes in their nests and even platforms for taking off. During the time of take-off, the soldiers are on guard at the exit holes to prevent both enemies as well as alates from entering into the nest from outside. During the time of emergence, alates get attracted by outdoor lights and escape from the exit holes. They are generally weak fliers and usually drop off just feet away from their mother colony. Swarming occurs from several colonies and this leads to inter colony breeding.
Nests of The Termite Insect
Termites have a relatively soft exoskeleton and therefore they build their nests well to protect themselves. The nests are warm, dark, and damp and completely shut off from the external world. These nests are a result of the contribution of workers and nymphs. The insides of the nest are extremely humid as a result of fluids produced by the metabolism in individual termites. The warm temperature provides an optimal climate for the growth of termites.
The protozoans which carry out the digestion of cellulose are primarily anaerobic and hence cannot survive in excess oxygen. As a result, termites have adapted to survival in high concentrations of carbon dioxide, going up to 3%. However, ventilation is still crucial and is carried out by pores in the nest built to act as ventilators.
Termites are extremely industrious insects who have built a structured society for themselves and have found the most suitable methods for their survival. Everything from the termite colony to the nests takes time to build but the distribution of labour among the members of the colony helps to achieve growth of both the colony and the species.
Did You Know?
Termites have lived for roughly over 200 million years, appearing even earlier than dinosaurs.
Some termites have been recorded eating plastics, fabrics, and wallpapers.
Termite mounds are huge and can reach heights of up to 35 to 40 feet.
Termites have incredible speed and are acclaimed as having the fastest movement in the world of insects.
FAQs on Termite
Q1. How Does Mating Take Place Once Alates Fly Off from Their Colonies?
Answer: During emergence, alates escape their original colonies through exit holes in their nests and get carried by winds to new lands. Here, they must form colonies through inter colony mating between alates. Upon landing, these alates almost entirely shed their wings, leaving just the base of the wing which is attached to the thorax. The females then begin a ritual where they raise their abdomen to release a chemical that excites the males and hence commences a short but indispensable mating ritual. Males and females form pairs and they look for mating spots with the males closely following their female partners. The couple mate in a hole or crack in wood or soil which they seal with their feces. During copulation, sperm from the king is transferred to the spermatheca of the female. Males do not have external copulatory organs and the sperm is released from a pore in the abdominal plate.
Q2. What happens After the Copulation of Alates?
Answer: The first batch of eggs after copulation is usually less in numbers. After a couple of years as the colony matures, the female develops and grows a large abdomen through a process called physogastry. Physogastric females in certain species can reach lengths up to 11cm and can lay up to 36,000 eggs in a day. On the contrary, kings are just about 2cm long. The first batch of youngsters develops into workers and soldiers. During the initial years of the growth of a termite colony, the reproductives take care of all the members. Later on, this task is given to the nymphs. Winged adults emerge only when a colony is fully mature.
Q3. Briefly discuss the Roles of the Different Members in a Termite Colony.
Answer: There are Three Main Groups in a Colony:
The reproductives are the king-queen pair who have developed from winged adults after flying off from their colonies. Because they have lived outside the nest, these termites have a hardened exoskeleton and large compound eyes. This pair is known as the primary reproductive pair and their functions include dispersal, reproduction, and colony formation. During the beginning years of a colony, they also tend to the young and take care of the nest. If the king or queen dies they are replaced by less developed but sexually mature secondary reproductives.
Workers are sterile, wingless, pale insects with no eyes. They have hardened mouths adapted to chewing. They construct the nests, feed the members of the colony, take care of the young and carry out repairs. The worker castes are the members of the group which destroys man-made structures.
The main function of the soldiers is to fight off enemies and attackers. They have highly developed mandibles and they also have teeth on their hooked jaws. They have large and dark heads. Since soldiers are also blind, they trace and track their enemies using chemical means.