Termites are unique among insects in their ability to derive nutritional benefit from cellulose, which is the component of wood and plants that gives structural rigidity to cells. However, as a result of feeding on wood and cellulose containing products, termites can cause significant damage to man-made structures and the cellulose materials contained within.
Generally speaking, subterranean termites must stay in close reach of the soil at all times, lest they die from dehydration. Accordingly, wood touching soil is easily accessed and damaged by termites. However, subterranean termites also can build shelter tubing to travel between the soil and wood that is nearby, but not actually touching the soil. The shelter tubing provides a dark, moist environment that protects the termites from sunlight, predators, or dehydration. Termites may also build shelter tubes through the soil to avoid certain highly repellant termiticides.
To prevent termite damage, termite barrier insecticides have been applied to soil under and around dwellings for many years as a chemical barrier. Approaches have included the injection or spray application of large volumes of organic pesticides such as organophosphates and pyrethroids into soil prior to the pouring or construction of building foundations. However, this approach causes environmental concerns as the pesticide goes directly into the environment. Moreover, this approach has performance limitations because the pesticide is lost from the vicinity within a 3 to 10 year period, thereafter allowing termite access. Further, rain during construction or some other form of physical activity (digging, walking, pipe laying etc) breaks the barrier and often leads to premature failure of the insecticide treatment.
A different approach to termite control has been to apply borates to wood used in construction through spray or pressure applications to poison the termites' food source. Borates have been used in almost all types of wood end use including the treatment of solid wood, plywood and wood composites. The benefits of borates include efficacy against all wood destroying organisms (fingi, boring beetles & termites), low acute mammalian toxicity and low environmental impact. As an example of this approach, a specific glycol borate formulation containing 40 wt. % disodium octaborate tetrahydrate (DOT) and applied diluted in water to 23 wt. % DOT (available commercially as BORA-CARE®), has been demonstrated and approved in the USA as a stand alone alternative to soil poisoning, when sprayed on all structural wood to a height of two feet in new construction.
However, treating only structural wood with borates has practical limitations. One limitation of this approach is that a large percentage of new construction uses building materials other than wood. Brick, block, concrete, steel frame, vinyl, stucco, gypsum, expanded foam and polystyrene board are all common construction materials that can be used in the absence of wood, or with a very low volume of wood. While termites generally don't directly damage non-cellulosic materials such as concrete, termites have the ability to build shelter tubing over these non-wood construction materials and then cause damage to books, paper, wall coverings, wood composite fixtures and fitting, hardwood floors, and other wood or cellulose items. Thus, while it is not effective to treat homes and commercial building constructed in this way by treating only structural wood with borates, subterranean termite protection is still warranted.
Another approach to the use of borates has been to incorporate them into building products, including cementitious products. However, this approach has not proven effective as it still allows termite tubing over the building material so the terminates can reach other vulnerable items. This approach has a further limitation in that the application of borates to cementitious products may act as a setting retardant and ultimately affect structural integrity of some building products into which it is incorporated.
Therefore, a need exists for an environmentally safer way of protecting man-made structures made with non-wood materials, and the contents therein, from termite damage.