Effect of extractive fractions of Thuja plicata and Chamaecyparis nootkatensis heartwood on Coptotermes formosanus
A Taylor, B L Gartner, J J Morrell, K Tsunoda
Heartwood of some species has natural resistance to attack by termites due to the presence of toxic and/or repellent extractives, but the role of individual extractives in termite inhibition is poorly understood. Developing a better understanding of which extractives are most effective against termites may be useful for the identification of improved termite management strategies. The effect of selective extractive removal on termite resistance was assessed using matched samples of Thuja plicata (D.Don) and Chamaecyparis nootkatensis (D.Don) Spach heartwood. Samples were extracted using a variety of solvents and then exposed to Coptotermes formosanus Shiraki in a no-choice feeding test. The results suggest that the methanol-soluble extractives in Thuja plicata and Chamaecyparis nootkatensis play important roles in making the heartwood resistant to attack by Coptotermes formosanus. Volatile and hexane-soluble extractives were less important. Further analysis of specific extractive compounds are underway.