This paper discusses the control of the Formosan Subterranean termite, Coptotermes formosanus, SHIRAKI with bifenthrin as studied under laboratory and field conditions. Observations were made as to the stability of bifenthrin on soil covered by a concrete slab and its volatility potential following soil treatment.
The soil residual activity of bifenthrin applied at 1 ppm to mountain soil was assesed to be very high over the two year observation period. However, in termite's field soil, Kawachinagano clay loam and volcanic ash soils, the control of termites declined over time although high soil residue levels were detected. The differences obsereved bitween biological activities and soil residue level was felt to be due to some adhesion of bifenthrin to the soil particles in these particular soil. Residue levels in soils under concrete slabs aged for two to four weeks at elevated temperatures of 50°C were lower than in soils held at room temperature. It was concluded that bifenthrin was relatively stable under alkaline condition. Bifenthrin is expected to perform consistently when applications are made pre-construction to concrete structures.
Evaluations using the under-floor method with a box at Fukiagehama in Kagoshima prefecture demonstrated very good wood protection over a five year period at an application concentration of bifenthrin at 0.05%. In the treated stake test, very good wood protection was achieved with concentrations of 0.025 to 0.1% over a four year period. Unfortunately the fifth year results could not be obtained due to excessive fungal attack of the stakes. Monitoring studies of air directly above treated soils did not result in detectable levels of bifenthrin suggesting that the potential for inhalation intoxication by the applicators would be negligible.
The results from these studies suggested that bifenthrin will provide excellent wood protection against termites at low concentrations and the risk from inhalation intoxication from treated soil is expected to be low.

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Wood composites with crosslinked acrylic copolymer, which includes DBT-DL (di-n-butyl tin dilaurate) as a crosslinking acceletor and stabilizer, were exposed to a brown-rot (TYP), a white-rot fungus (COV) and termite for investigation of the effects of the amount of DBT-DL on the biological resistance. The bare DBT-DL significantly affected TYP and termite as inhibitor of biodegradation but 4.994 mg of DBT-DL to 1g of wood was required for decay resistance to COV.
When DBT-DL coexisted together with crosslinking copolymers, 6.075 mg of DBT-DL to 1g of wood was required for surpression of the attack by TYP, and the weight loss for termite attack was about 10% under the same condition. DBT-DL was assumed to reduce its toxicity against TYP and termites by the coexistance of the copolymer. The coexistance of these copolymers and DBT-DL, however, was considered to improve the safety of the composite because of prevention of the chemical elution into water.

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[in Japanese]

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