Impact of thermal modification on the protection of Eucalyptus wood against termite attack

The thermal modification alters the physical-chemical and mechanical properties of wood, potentially increasing its natural durability. Based on this, the objective of this study was to analyze the effects of thermal modification on wood from Eucalyptus grandis W. Hill ex Maiden × Eucalyptus urophylla S. T. Blake clones and its impact on chemical properties and biological resistance against drywood and subterranean termites. Wood samples from each clone were subjected to a heating ramp up to 185 and 200 °C. Chemically, the ash content (%) and total extractives (%) were analyzed. Biological resistance was assessed through choice feeding and no-choice feeding tests with drywood and subterranean termites. The parameters evaluated included mass loss, wood damage, number of holes (drywood termites), and termite mortality (no-choice feeding). After thermal modification, a decrease in total extractive content was observed. As for ash content, clone C showed an increase, while clone E presented a reduction. In the choice feeding tests with both termite groups, the samples thermally modified at 185 °C were the most consumed. In the no-choice feeding tests with drywood termites, clone C showed lower mass loss and fewer holes compared to clones A and E. It was concluded that thermal modification at the tested temperatures (185 and 200 °C) made the wood of E. grandis × E. urophylla clones more susceptible to attack by drywood and subterranean termites.