It is generally assumed that termites will voraciously feed on all types of wood, and that there is no type of wood that termites will avoid consuming. This assumption seems reasonable, after all, if termite-resistant wood existed, then why would homebuilders ignore these wood sources in favor of lumber that is well known to be consumed by termites? However, numerous living tree and leafy plant species have the ability to defend against injuries inflicted by insect pests, and these plant species are particularly abundant in tropical areas where freezing temperatures do not kill off insect pests. Numerous trees have evolved to repel insect pests that feed on them by producing defensive chemicals called “extractives.” Many researchers strongly believe that more work should be done to isolate these defensive chemicals from certain trees, as the chemicals could be effectively used as organic insecticides. Many researchers are in agreement that termite-resistant types of wood should be manufactured into lumber for home-building. While termite-resistant woods have been largely ignored for most of modern history, the lumber industry is now starting to fund research into termite-resistant tree species that can be manufactured into lumber. During the 2000s, researchers conducted a study to find which domestic and tropical tree species are resistant to eastern subterranean termites, the most costly termite pest species in the US, and the only termite to inhabit the northeast states.
The Alaska-yellow cedar tree is one of the most termite-resistant tree species yet found in the US. Research shows that this tree produces nootkatone oil and allelochemicals, such as terpenoids, quinones and phenolics, that repel eastern subterranean termites. Tests showed that southern-yellow pine suffered the most extensive termite damage, while Atlantic white cedar suffered very little or no termite damage. Ipe, a tropical timber found in South America had sustained the least amount of damage from eastern subterranean termites. Seven other exotic timbers, teak, iroko, mahogany, Australian cypress pine, niove, greenheart, and holywood lignumvitae were found to be most resistant to termite damage, while two types of oak, black locust, Osage-orange, and redwood proved to be the most termite-resistant domestic timbers. Douglas fir species were low to moderately resistant to eastern subterranean termite attacks, but this timber species did not become much more resistant to termite attacks after being treated with two different wood preservatives. This explains why Douglas fir lumber is frequently attacked by eastern subterranean termites.
Were you aware that termite-resistant timber species existed in nature?