The termiticidal efficacy of sodium octaborate tetrahydrate, boric acid, borester-7, and tri-methyl borate as wood preservatives was evaluated after each was impregnated into seasoned sapwood of Pinus radiata D. Don and Eucalyptus regnans F. Muell in laboratory bioassay against Coptotermes acinaciformis (Froggatt). There was clear difference between the different borate retentions in treated and untreated blocks, mass loss, and mortality rate of the termite used in the bioassay units. After 8 weeks of laboratory bioassay, the results suggested that borate was toxic to termites even at 0.24% m/m BAE and caused significant termite mortality, but termites were not deterred from attacking the borate-treated timber at a higher retention of >2.0% m/m BAE. These laboratory results indicated that the minimum borate treatment required to protect timber against termite attack and damage was >1.0% m/m BAE.
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