ROLE OF TERMITES IN ECOSYSTEM
Rida Zainab*1, Haider Ali*2, Zain ul Abdin*2, Fiaz Hussain*2,Amir Sohail*2Kanza Ghaffar*1
*2Department of Zoology, University of Agriculture, Faisalabad, Pakistan
*2Department of Entomology, University of Agriculture, Faisalabad, Pakistan
Corresponding Author: Rida Zainab
Termites (Order: Isoptera) are serious pests of agricultural, horticultural and plantation crops including forest trees, especially in the semi arid and sub-humid tropics and cause significant yield losses. Termites are the most economically important wood destroying pests in the world. Termites contribute significantly to world ecosystems by recycling the materials resulting in the maintenance of nutrient composition and balance. They are of great importance in recycling nutrients and soil fertilization in forest ecosystems. In subtropical and temperate parts of the world, termites are low in diversity, but still they play major role in forest ecosystem. Termites are among the most successful groups of insects on Earth, colonizing most landmasses except for Antarctica. Their colonies range in size from a few hundred individuals to enormous societies with several million individual.
Termites are usually small, measuring between 4 to 15 millimeter’s in length. The largest of all extant termites are the queens of the species Macrotermes bellicosus, measuring up to over 10 centimeters in length. Another giant termite, the extinct Gyatermes styriensis, flourished in Austria during the Miocene and had a wingspan of 76 millimetres and a body length of 25 millimetres.
DISTRIBUTION AND DIVERSITY:
More than 2800 species in about 200 genera distributed over nine families and fourteen subfamilies is presently recognized. Agriculturally important termites include genera from the following families: Hodotermitidae (Anacanthotermes, Hodotermes), Kalotermitidae (Neotermes), Rhinotermitidae (Copotermes, Heterotermes and Psammotermes) and Termitidae (Amitermes, Aneistrotermes, Cornitermes, Macrotermes, Microcerotermes, Microtermes, Odontotermes, Procornitermes and Syntermes).
ATTACKS OF TERMITES:
Attack of termites on living woody plants (trees) are rarely registered. Wood of living trees is primarily used as a food resource by the lower termites, mainly by species of the genera Zootermopsis (Termopsidae), Heterotermes, Schedorhinotermes, Reticulitermes, Coptotermes (Rhinotermitidae) and by members of the Mastotermitidae and Kalotermitidae .The hardwood in the center of living trees is biologically dead tissue and, as such, susceptible to attack by xylophagous insects, but the living tissue and the bark protect the core of the tree. They attack roots and above ground parts, attack wooden structures, timber and paper.
SOCIAL BEHAVIOUR OF TERMITES:
Termites are social insects that live in colonies and have several hundreds to over a million termite individuals. Termite colony is composed of reproductive generations (queen and king) which are few in number within the termite colony. Termite produce winged reproductives which fly on certain period of the year. There are numerous apterous (without wings) non reproductive soldiers and workers in termite colony. Workers and soldiers are sexually immature and blind. Workers’ main task is to feed the colony, construct galleries, and hatch eggs etc while soldiers defend the colony from predators. All the colony members share food, water and shelter. Majority of insects like termites, ants and aphids produce winged adults, whose only function is to migrate and propagate the species. In Pakistan, various workers have studied the swarming pattern of termites and have correlated it with rainfall and temperature. After swarming male and female fall on ground, show tendon running male closely follows the female, shed off wings and pair. A male (king) and female (queen) pair to establish colony. The pair will move to a moist or damp area to initiate a new colony. The queen’s major role is to lay eggs, for that purpose she develops an enlarged abdomen containing ovarioles and associated tissues, a condition known as being physogastric. The first batch of eggs is produced by the female within a few days. The hatched youngones are translucent white and feeble at first, but very active from the moment they are hatched. These larvae are fed from nutrient-rich salivary secretions produced by the parents. They normally undergo a number of moults until they achieve the mature form as sterile workers or soldiers, depending to the need of the colony .These developments are determined by extrinsic factors such as pheromones and hormones .Usually, at the beginning of a colony foundation the larva become workers and occasionally the larvae develops large dark brown head with protruded jaws of quite distinct shape, into a soldier .The colony grows slowly for many years, accompanied by a continuous increase of termite population, enlargement of the nest and much building activity .
The life cycle of a termite begins with an egg, but is different from that of a bee or ant in that it goes through a developmental process called incomplete metamorphosis, with egg, nymph and adult stages. Nymphs resemble small adults, and go through a series of moults as they grow. In some species, eggs go through four moulting stages and nymphs go through three. Nymphs first moult into workers, and then some workers go through further moulting and become soldiers or alates; workers become alates only by moulting into alate nymphs.
Termites (Isoptera) are arguably the most important soil ecosystem engineers Termites have the abilities to forage over long distances (metres to tens of metres) and to partially control their own living environments through the creation of nest structures where the humidity and temperature remain constant throughout all seasons. This gives them a striking ability to remain active in harsh environments, or during severe seasons, where most other soil macroinvertebrates are diminished or eliminated. For instance in arid and semi-arid tropical savannas, during the dry season termites remain virtually the only active group of invertebrate detritivores and bioturbators, consequently dominating the decomposition processes and the provision of essential ecosystem services.
FEEDING IN TERMITES:
A wide range of termite species typically feed on dead plant material such as wood, bark and straw, being able to digest woody fibres with the assistance of the gut microbiota, supplementing endogenous enzymes .Even animal products, such as mammalian hooves and dungs, can also be consumed though spatially and temporally variable .Like shredder organisms, termites can mechanically chop up plant material with their mandibles and grind it with their gizzard, thereby increasing the surface area accessible to soil microorganisms, as well as their own intestinal symbionts and speeding up net decay by protist, bacterial and fungal agents.
BIOTURBATION AND SOIL FORMATION:
One of the major effects of termites in ecosystems is their role in soil loosening (reduction of bulk density) and both vertical and horizontal transport through bioturbation, and subsequent erosions of their constructions. This is especially true with termites of the subfamily Macrotermitinae. The magnitude and route of soil translocation resulting from termite activity is directly related to their specific dietary habits and the properties of the soil they use .The mounds of humivorous termites are built with materials coming mainly from the surface horizon and recycled at this level by erosion. Over time these effects of termites on soil translocation will have strong consequences on the profile, making termites agents of pedogenesis as well as responsible for the distribution of resources in the ecosystem.
TERMITES FOR THE PROMOTION OF ECOSYSTEM:
Utilization of termites for the promotion of ecosystem services in agro-ecosystems. Although their regulatory role in natural habitats is widely recognized, few studies have been made to test whether termite activity can be manipulated for the promotion of ecosystem processes and therefore the provision of goods and services in agro-ecosystems. Certainly, the higher nutrient content in termite mounds has led to their use as soil amendments in many traditional agricultural practices, resulting in better crop yields .Moreover, termite mounds can foster the development of mycorrhizal fungi and even assist in the control of crop pests, The ability of termites to develop in harsh environments and to promote water infiltration in crusted soils as a part of soil rehabilitation and vegetation cover regeneration has been strikingly demonstrated in Africa and Asia. In these studies, the application of mulch or organic matter on or into the soil, as in the case of the agricultural and forestry “zaï” systems, triggered the activity of termites which then created burrows opened through the sealed surface of the soil The change of soil characteristics due to termite activity is enough to create the conditions necessary for natural vegetation development and then crop production on previously degraded bare soils.
From the above discussion, it could be concluded that besides the economic losses caused by termites as forest insect pests, they are also considered as useful insects as decomposers of dead organic matters and increases the fertility of the soils too leading toward the concept that the termites have significant role in Ecosystem and that’s why they are called as Ecosystem Engineers.