Natural durability of tropical and native woods against termite damage by Reticulitermes flavipes (Kollar)

Environmental pressure has resulted in voluntary removal of chromated copper arsenate (CCA) from wood preservatives in residential applications in the United States. A new generation of copper organic preservatives was formulated as replacements, but these preservatives may not provide a permanent solution to all related problems. Some of these issues include concern over copper in aquatic environments and corrosion of fasteners. Copper preservatives in general are also poor inhibitors of mould. Therefore, we still need to evaluate alternative solutions in order to address current inadequacies of copper organic wood preservatives. In this study, six hardwoods and six softwoods were evaluated for their ability to resist termite damage by Reticulitermes flavipes. Mass loss versus specific gravity showed an inverse correlation in tropical hardwood species, but a slightly positive correlation in native softwood species. Also, southern yellow pine and Douglas-fir wood blocks were evaluated after treatment with 0.1% copper borate, water-borne (WB) copper naphthanate, and N′N-naphthaloylhydroxylamine (NHA). Erisma, juniper, ipe, and white-cedar were highly resistant. The NHA-protected Douglas-fir and southern pine resisted attack as effectively as copper borate or WB copper naphthanate treatment. These results indicate that selected naturally durable wood species, both tropical and native, inhibit R. flavipes damage as effectively as preservative treatment.