Termites: Economic Importance Of Termites
Introduction
Termites all belong to the phylum Arthropoda, the class Insecta, and the order Isoptera. There are over 2,000 different species of termites with over 40 species in the United States alone. Although they have distinct characteristics, most look similar. They typically measure between 1/4 and 1/2 of an inch long and have soft bodies with straight antennae. The queens and kings are larger, capable of reaching over one inch long. Colors range from white to light brown where worker termites often appear lighter, while swarming termites darker. Flying termites, also called reproductives, have two pairs of prominent wings.
Termites are among the most successful groups of insects on Earth, colonising most landmasses except Antarctica. Their colonies range in size from a few hundred individuals to enormous societies with several million individuals. Termite queens have the longest lifespan of any insect in the world, with some queens reportedly living up to 30 to 50 years. Unlike ants, which undergo a complete metamorphosis, each individual termite goes through an incomplete metamorphosis that proceeds through egg, nymph, and adult stages. Colonies are described as superorganisms because the termites form part of a self-regulating entity: the colony itself.
Termites are a delicacy in the diet of some human cultures and are used in many traditional medicines. Several hundred species are economically significant as pests that can cause serious damage to buildings, crops, or plantation forests.
Economic Importance Of Termites
What are termites?
Termites are eusocial insects that are classified at the taxonomic rank of infraorder Isoptera, or as epifamily Termitoidae within the cockroach order Blattodea. Termites were once classified in a separate order from cockroaches, but recent phylogenetic studies indicate that they evolved from close ancestors of cockroaches during the Jurassic or Triassic. However, the first termites possibly emerged during the Permian or even the Carboniferous. About 3,106 species are currently described, with a few hundred more left to be described. Although these insects are often called “white ants”, they are not ants.
As decomposers termites feed on living or decaying wood. A major compound of wood is cellulose, a carbohydrate like starch. Breaking down cellulose requires an enzyme called cellulase. Some termite species have the ability to produce this enzyme, others live in mutualistic symbiosis with certain intestinal bacteria or protozoa, that provide the required cellulase. In order to cover their protein requirements, termites feed on fungi, growing on decaying wood. The importance of fungi for termites can be seen from the fact that a young queen on her colonising flight carries a bit of the fungi cake in her mouth. Once she settles down to found a new colony, she inoculates chewed wood with the fungus. Most termite species are harmless to timber and timber products, but others are even so hungry that they chew the plastic insulation of subterranean power and telephone cables.
Most termite species are utterly beneficial decomposers contributing towards a rapid recycling and turn-over of minerals. However, a handful of species are some of the most destructive pests of untreated timber products as well as of living standing trees causing, an economic loss of many millions of Kina every year. Characteristic of this group of insects are their chewing mouthparts and the ability to digest cellulose, the major component of wood. Termites chew and bore timber, causing either a considerable degrade of the material or resulting in the death of the host tree.
Termites are social insects having three distinct castes, the reproductives (queen and king), the soldiers and workers. The colony can consist of more than a million individuals. The nest of a colony (termitarium) is located either underground (subterranean), on a tree (arboreal) or in a mound sticking out of the soil. Due to the unpigmented skin of most termites, they have to live in dark and moist conditions, protected from desiccation. Therefore the insects move only in the very long subterranean galleries or shelter tubes extending from their nest to gather food. Termites are sometimes difficult to identify and usually the soldiers are used for that purpose. Characteristic and thus helpful for identification is their nest type.
The most significant termite species in terms of economic loss are Microcerotermes biroi, Nasutitermes novarumhebridarium and Coptotermes elisae since all three species attack living trees of any age. They have the potential to kill their host within a few months, however in some cases the attack can take several years without any external symptoms, until the tree is thrown over by wind.
Important is that termites usually only attack trees that are somehow weakened or otherwise under stress. Weakened trees release a volatile chemical (kairomone) which is used by the termites to locate the diseased tree. Once attacked by termites, the tree is quite helpless, because its natural immune system or resistance is decreased and pests cannot longer be defeated effectively. The symptoms of termite infestations are more or less conspicuous and obvious, however in some cases an apparently healthy tree suddenly dies without having shown any external signs.
43 termite species are used as food by humans or are fed to livestock. These insects are particularly important in less developed countries where malnutrition is common, as the protein from termites can help improve the human diet. Termites are consumed in many regions globally, but this practice has only become popular in developed nations in recent years.
Termites are consumed by people in many different cultures around the world. In Africa, the alates are an important factor in the diets of native populations. Tribes have different ways of collecting or cultivating insects; sometimes tribes collect soldiers from several species. Though harder to acquire, queens are regarded as a delicacy. Termite alates are high in nutrition with adequate levels of fat and protein. They are regarded as pleasant in taste, having a nut-like flavour after they are cooked.
Alates are collected when the rainy season begins. During a nuptial flight, they are typically seen around lights to which they are attracted, and so nets are set up on lamps and captured alates are later collected. The wings are removed through a technique that is similar to winnowing. The best result comes when they are lightly roasted on a hot plate or fried until crisp. Oil is not required as their bodies usually contain sufficient amounts of oil. Termites are typically eaten when livestock is lean and tribal crops have not yet developed or produced any food, or if food stocks from a previous growing season are limited.
In addition to Africa, termites are consumed in local or tribal areas in Asia and North and South America. In Australia, Indigenous Australians are aware that termites are edible but do not consume them even in times of scarcity; there are few explanations as to why. Termite mounds are the main sources of soil consumption (geophagy) in many countries including Kenya, Tanzania, Zambia, Zimbabwe and South Africa. Researchers have suggested that termites are suitable candidates for human consumption and space agriculture, as they are high in protein and can be used to convert inedible waste to consumable products for humans.
Economic Importance Of Termites
Agricultural importance
Termites can be major agricultural pests, particularly in East Africa and North Asia, where crop losses can be severe (3–100% in crop loss in Africa). Counterbalancing this is the greatly improved water infiltration where termite tunnels in the soil allow rainwater to soak in deeply, which helps reduce runoff and consequent soil erosion through bioturbation. In South America, cultivated plants such as eucalyptus, upland rice and sugarcane can be severely damaged by termite infestations, with attacks on leaves, roots and woody tissue.
Termites can also attack other plants, including cassava, coffee, cotton, fruit trees, maize, peanuts, soybeans and vegetables. Mounds can disrupt farming activities, making it difficult for farmers to operate farming machinery; however, despite farmers’ dislike of the mounds, it is often the case that no net loss of production occurs. Termites can be beneficial to agriculture, such as by boosting crop yields and enriching the soil. Termites and ants can re-colonise untilled land that contains crop stubble, which colonies use for nourishment when they establish their nests. The presence of nests in fields enables larger amounts of rainwater to soak into the ground and increases the amount of nitrogen in the soil, both essential for the growth of crops.
