Chemical Control

Chemical control of termites is by far the most extensively practiced control measure. Numerous chemicals are used, and these can be broadly classified on the basis of their pattern of use.

Baiting With Slow Acting Toxicants

Baiting with a slow acting toxicant is a very cold concept in termite control that has only recently been widely implemented because older toxicants were very toxic to human being. Arsenic dust is no longer permitted for use in Malaysia for this reason. There are currently two dusts formulation approved for similar usage in Malaysia ie deltamethrin and amorphous silicon dioxide

The recent chemicals used as slow acting toxicants are generally used as baits, that is, food material for termites impregnated with the chemicals. They act by interfering with the normal growth and reproductive mechanism of the termites. They are all insect growth regulators (IGRs) , that is, insect growth hormones that inhibit the making of chitin (I.e., chitin synthesis inhibitors), a substance required for the insect’s hard outer coat and egg shells. Only hexaflumuron has reached the Malaysian market thus far, and it is marketed as a system of baiting and monitoring.

The concept behind baiting with a slow acting toxicant is that the termites feed on the chemical but do not die immediately and, therefore have the opportunity to pass the toxin on to other members of the colony through a process of mutual feeding that occurs in termites. The termite queen is also fed in this manner, thus she is also killed by the toxin without ever having directly fed on the baits. The process requires that the termites not only die slowly but that they also do not recognize that they are being poisoned and, therefore, do not abandon their feeding site or ostracise termites that have fed on the toxin.

When an infestation is detected in a building, outdoor stations are established in the ground perimeter of the building. These are essentially wooden stakes held in a cylindrical plastic holder, which is buried in the ground and has openings through which termites can enter. The plastic holders have a removable cover, which can be opened for regular inspection. Once a termite infestation is found in the wooden stakes, they are removed and replaced with tissue-like bait impregnated with the chemical, hexaflumuron, housed in a plastic cylinder with entrance holes. The termites from the original stakes are returned to the station so that they can feed on the bait and return to the colony, laying a chemical communication trail that tells other termites in the colony that they have encountered food. The chemical-impregnated bait is replaced at intervals. Additional baits are placed indoors where there are infestations, in special plastic receptacles. In Malaysia, after about 4-8 weeks, the termites disappear from the baiting site and the building. Studies have shown that if sufficient toxin reaches the colony, the queen and the entire colony can be destroyed.

Baiting is an efficient method of termite control because it targets the termite nest where the source of infestation lies. After elimination of the termites, monitoring can be carried out with the wooden bait stakes to forewarn of any new infestation.