Biocidal potential of the extractives of four Malaysian timbers against subterranean termites and wood decay fungi

Wood extracts of four selected Malaysian timbers, Neobalanocarpus heimii, Cotylelobium lanceolatum, Madhuca utilis and Shorea curtisii, were tested at various concentrations against the subterranean termites, Coptotermes curvignathus and C. gestroi, and the fungi, Trametes versicolor (white-rot), Lentinus sajor-caju (white-rot), and Coniophera puteana (brown-rot). Paper discs were treated with 0.5, 1, and 2% w/v extracts and exposed to termites using a no-choice test. For the wood decay test, blocks of a non-durable species, Hevea brasiliensis, were treated with 2, 4, 6, and 8% of each extractive concentration and exposed to termites for a 12-week period. The results showed that 2% w/v of N. heimii extract was highly effective against both the termite species, C. curvignathus and C. gestroi after 10 days of exposure, leading to complete mortality with slight attack of the filter paper (mass loss = 1.10% and 0.69%, respectively). The 0.5% w/v extract resulted in 50% termite mortality with 2.53% and 1.42% filter paper consumption. Maximum weight losses were observed with 2% of each wood extractive against each fungus tested. Higher concentrations were needed when it comes to controlling fungi. The results from this study indicate that Malaysian wood extracts show some promise as alternative termiticides or fungicides.