Envelope wood protection against subterranean termites under H2-hazard class tropical environment by a new generation wood preservative with vegetal extracts-cypermethrin mixtures
IRG/WP 23-30795
D Messaoudi, A H H Wong
Wood protection industries in progressive economies globally are compelled to develop cost-effective, environmentally acceptable wood treatment solutions for long term carbon storage in wood materials/products while appealing to consumer demands for low environmental impact treated wood. A new generation wood preservative, based in part on 2% vegetal extracts and 0.16% cypermethrin components, has considerable potential in conferring long term wood protection against subterranean termites when exposed to indoor aboveground contact. Applying only brush-on (envelope) treatment of tropical kempas (Koompassia malaccensis) hardwood with this ready-to-use preservative and subsequently subjecting air dried treated wood to a rigorous laboratory evaporative ageing protocol (regarded as H2-weathered treated wood), an H2-hazard class aboveground subterranean termite field test design (Wong 2005) was used to determine the termite resistance of such treated wood. Reference surface-treatment (by 3 minute dipping) preservative was a commercial LOSP containing partly 0.2% permethrin. After 6 months exposure of treated wood at a forest site against Coptotermes curvignathus, results demonstrated irrefutably that unprotected kempas heartwood was severely attacked by C. curvignathus (mean mass loss: 70.4% and 20,416 mg) with low mean visual termite rating (2.4), unlike the kempas TOTALLY protected by both the new generation preservative and the reference LOSP preservative despite very low surface pyrethroid retention detected from these treatments. This cypermethrin-based formulation therefore shows considerable long-term anti-termite potential, and substitute for the hazardous LOS-based permethrin, for indoor aboveground hardwood protection.