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A Contribution of ICAR National Fellow Project

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Barrier Technology


Physical Barrier:

Fine material particles viz. sand and crushed volcanic cinders were reported to have potential to work as barrier against subterrenean termite Reticulitermes hesperus. This barrier was impenetrable for termites because of heaviness of the particles for termites to carry away, and act as disruptors for building gallery. Particle size of sand may regulate the termite penetration, thus could be used as effective physical barrier. Logan and his co-worker reported the particle size should be between 1.7 and 2.4 mm to act as effective barrier. Singh and Rawat showed that the larger sized sand particles could lower the rate of gallery formation in Microtermes beesoni. Formation of sand barrier near the foundation of a construction can be effective in preventing termite attack on it. Moisture level in sand also affects aggregation of termites. Experiment with Formosan subterranean termite Coptotermes formosanus Shiraki revealed least termite colonization at saturated or near saturated and almost dry condition of sand. In Indian scenario, the guidelines of Ministry of Railways, Govt. of India gave a clear-cut instruction of laying out the concrete flooring on a bed of coarse sand (size, > 3mm) in order to check soil moisture, thus acting as effective barrier against termite in various constructions. Sand or stainless barrier is effective in new construction, not for remedial measures. The earthen pots may be painted with red earth (termiticide-treated) or lime. Various physical barriers are also used to prevent termite attack to the structures. Installation of transparent plastic sheet just below DPC level of new buildings which can protect the construction from termite and dampness. Crushed stones, gravel aggregate, sand etc also proves to be physical barrier against subterranean termites. Particulate material barrier, if applied in the crawling space viz. under the pillars, beam foundation, terrace serve as good physical obstacle for termites attacking buildings. Small sized mesh made of stainless steel was found to be a good horizontal barrier for foraging of many termite species. The Termi-Mesh, a fine mesh made of stainless steel with holes 0.66x0.45 mm was found to act as a good barrier against termites to pass through. Use of physical barriers against termites in constructions and buildings though is a prospective way of protection, adequate knowledge and technology in this aspect is yet to be utilized properly in Indian context.

Humidity regulation plays a major role in insect pest management including termites. Two important subterranean termites, namely, C. formosanus and R. flavipes were experimented in United States on the survival in different ranges of temperature and humidity, which showed a clear-cut result of longer survival of termites in increased humidity level, while showing decline in reduced humidity condition. Increased feeding activities of western dry-wood termite Incisitermes minor (Hagen) was also reported at higher level of humidity. Influence of humidity on the life process of two subterranean termite species, viz. Reticulitermes flavipes and R. virginicus was reported from South Carolina (United States) where both species were found active in relative humidity 80% or above. Subterranean termites depend largely on the soil-moisture for survival; thus, could be effectively managed if they are abstained from supply of moisture. Installing dehumidifier in entry and crawling space of termites in a construction help protection of the building from this pest. Even though the technique of using dehumidifier to control termites by altering their natural requirement of humidity for survival is gaining popularity in many developed countries, in India, large application of this technique is yet to take over the market from currently ongoing anti-termite technologies.

Chemical barriers:

Chemical barriers can be broadly classified into two categories viz. repellant and non repellant. Non repellant chemicals used against termites include Chloranthraniliprole, Imidacloprid, Chlorfenapyr, Fipronil etc. Repellant chemicals include Chlorpyriphos, Bifenthrin, Permethrin etc. While using repellant chemicals termite can detect it and move away from the treated area resulting non transfer of toxicity to the other colony members. In case of non repellants, toxicity can not be detected earlier resulting in passing the lethal effect to the other colony members.

Common barrier treatments: Conventional methods of termite control at the time of building construction involve soil treatment with chemicals to provide a chemical barrier using Chlorpyriphos 20% EC as per recommendation of Indian Standard: 6313 in the year 2013. According to Rawat this process was reported to be useful for 5-7 years for providing protection to the structures by acting as barrier between soil and wood used in the construction. Owing to high toxicity of the above mentioned chemical termiticides, their application result into environmental hazard by getting assimilated in food chain and contaminating ground water.

Rodding:

Soil around the external perimeter of a construction was recommended to be treated using ‘rodding’ and pouring chemicals in order to set a chemical barrier. As recommended by Indian Standard 6313 in 2013, on completion of construction of a building, soil along the external perimeter should be rodded at 150 mm intervals and to a depth of 300mm. The rods should be moved parallel to the wall in both forward and backward direction to break up the soil. Now chemical emulsion should be applied along the wall and post treatment the soil should be stuffed back in the place.

Reticulation system:

Another popular practice of termite management in buildings of India is reticulation or tubing system in which, network of pipes are being laid beneath the floor. These pipes contain termiticide pumped inside them and with drippers it can be used according to need. This system gained popularity in India but success rate is dependent on the perfect installation [94].

Perimeter-treatment:

This is digging shallow trench/channel and application of termiticide solution @1.75 litre per running meter. Addition of 0.5 litre extra per running meter for back-filled soil-treatment (otherwise, 7.5 lit/m2 of vertical surface of sub structure, 30cm depth) is also recommended. For buildings with concrete or masonry apron, drilling 12mm holes @ 30cm distance close to plinth wall and injection of termiticide solution 2.25 lit/hole is suggested. For inside, drilling vertical 12 mm holes @ 30 cm distance close to the floor and wall and injection of termiticide maximum 1 lit/hole by pressure pump is suggested.


Last Updated: 04-01-2020

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