Damages brought about by termites are estimated to cost US$40 billion worldwide each year.
Termites are considered social insects and are grouped under the order Blattodea. They have close phylogenetic relationships with cockroaches and are occasionally regarded as social cockroaches. There are about 3,105 species of termites described but only a small fragment of this number are considered pests to buildings and structures.
METHOD OF TREATMENT FOR TERMITES
Chemical treatment remains as the most effective method in termite management. Soil treatment, physical barrier, dusting and baiting (only works against Coptotermes species) are among the methods used to treat termite infestation.
Soil treatment can be applied as:
1) Pre-construction treatment – Carried out during the construction phase of a structure or building. The diluted termiticide is drenched on the soil before the concrete slab is laid on the soil.
2) Corrective soil treatment – Performed after a building is constructed. It produces a treated zone between the building and subterranean termites. It involves drilling holes on floor slab (along the perimeter of the walls, around pipings, or locations where subterranean termites most likely will attack) at regular intervals and injecting diluted liquid termiticide into the holes.
There are two main group of chemicals used in soil treatment:
1) Repellent termiticides: It is designed to only repel termites and hence, termites avoid the lethal contact. Therefore, there is a possibility it would not eliminate the entire colony.
2) Non-repellent termiticides: It does not repel the termites away. Termites will forage into the treated soil and will then be exposed to the toxicant. The toxicant used will be slow-acting which allows termite workers to transfer the toxicants to non-exposed termite workers and their colony members. Concentrations used are usually lower than repellent termiticides, and non-repellent termiticides have little or negligible impact on the environment.
SIGNS OF TERMITE INFESTATION
A termite infestation can be identified by:
1) Damage to wood structure – Observation of damage on the wood flooring (flooring or skirting boards), wooden ceiling damage (wooden ceiling, beams, wooden frames in attics) and wooden walls.
2) Hollow sounds from wood – If it’s termite damage, knocking or tapping over the damage wood would produce a hollow sound, as this would mean that the internal part of the wood/timber has been consumed by the termites.
3) Presence of termite mud tubes – These are the “shelter” tubes constructed by termites, which protect them from dehydration when they travel above ground. These mud tubes are made of small particles of soil, sand and faecal material with saliva.
4) Termite presence – When removing small parts of the damaged wood or small parts of the mud tubes – Usually the worker and soldier termite will emerge out.
5) For drywood termites, termite droppings can be observed – drywood termite infestations always leave behind droppings or frass.
TYPES OF TERMITES
Termites can be classified under three groups:
1) Drywood Termites
Drywood termites are a pest of drywood (e.g. structural timber in buildings). They do not rely a lot on moisture sources and do not need soil for survival.
2) Dampwood Termites
Dampwood termites often feed on decayed food from rotting logs, timbers buried or stumps of old trees.
3) Subterranean Termites.
Subterranean termites, on the other hand, construct their nests in the soil and heavily rely on moisture for survival. They utilise mud tubes to prevent dehydration when they travel above ground to search for cellulose food sources. Subterranean termites are the most damaging to buildings and structures, among the three groups of termites described.
The species of subterranean termite which commonly attacks buildings and structures is Coptotermes gestroi. This species is a cryptic species and they do not build mounds. Hence, it is often difficult to determine their presence because they forage under the soil, unless a complete termite monitoring system is set up around the building. Coptotermes gestroi contribute about >90% of all subterranean termite attacks. Other major subterranean termite species are the mound-building species, such as Macrotermes carbonarius, Macrotermes gilvus, and Globitermes sulphureus. These mound-building termite species do not attack buildings or structures often, and contribute less than 10% of the total attacks from subterranean termites.
In a termite colony, there are immatures (nymphs and larvae), alates (swarmers), reproductives, soldiers and workers. Worker termites are the most abundant in the colony and they are involved in gathering food, feeding other castes, grooming, making tunnels and excavating the nests. Soldier termites are involved in colony defence and usually gather at the opening of the nest or mud tubes for defence.