Effect of eucalyptus wood vinegar on rubberwood infestation by Asian subterranean termite, Coptotermes gestroi Isoptera: Rhinotermitidae).

Wood degradation caused by fungi, termites, and insects, is a major problem for the rubberwood industry. The potential of wood vinegar as rubberwood preservative was studied. The infestation rates of Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae) on rubberwood samples treated with 25%, 50% and 100% eucalyptus wood vinegar for 24 hours were observed in laboratory conditions. Both non-choice and choice experiments were included. The effects of eucalyptus wood vinegar treatment depended on its concentration. In the non-choice experiments, rubberwood samples treated with 100% eucalyptus wood vinegar had the highest resistance to C. gestroi infestation, with the lowest relative loss of mass, followed in rank order by 50% and 25% treatments. However, in the choice experiments the relative loss of mass did not differ significantly between the treatments with varied wood vinegar concentration. Untreated control samples were distinctly infested by C. gestroi in both non-choice and choice experiments, but their relative loss of mass in the non-choice experiments was not significantly different from samples treated with 25% eucalyptus wood vinegar. Hence, 25% eucalyptus wood vinegar was not effective as rubberwood preservative against C. gestroi attack. The results suggest that eucalyptus wood vinegar acts as a rubberwood preservative against termites, provided the treatment is done without dilution. About 50% dilution still has some efficacy, while lower concentrations are not effective.