Termites are the most economically damaging insect pests in the world, and unfortunately, they are particularly common throughout Louisiana, particularly in New Orleans. Globally, termite destruction to structural wood within homes and buildings costs more than 40 billion dollars to repair, and more than 600,000 homes sustain termite damage annually in the US alone. The degree to which termites damage wood depends on several factors, such as termite species, colony size, wood species, the age of wood, the moisture content of wood, and the type of preservative/s used to treat wood.

Many types of preservative chemicals are used to treat wood in order to render lumber resistant to decay, moisture retention and termite attacks. In the US, chromated copper arsenate is the most commonly used wood preservative, and while this chemical is largely effective at protecting wood from termite attack, the demand for environmentally friendly wood treatments are becoming increasingly popular among green-minded consumers. In response to this demand, entomologists Mary L. Cornelius and Weste L. Osbrink with the Agricultural Research Service are investigating wood species that are naturally resistant to termite attack.

Researchers have long known that trees have evolved to protect themselves from wood-burrowing insects by emitting allelochemicals. Allelochemicals are emitted from the heartwood of trees and their toxic effect on termites repels and even kills the pests. Cornelius and Osbrink are carrying out experiments to determine if allelochemicals remain within wood after being processed into lumber. After subjecting Formosan subterranean termites to commercial lumber sourced from 10 different tree species, they found that redwood, Brazilian jatoba, Peruvian walnut, Honduran mahogany, Alaska yellow cedar, and teak demonstrated some natural resistance to termite attack, and an average of 75 percent of all termites that consumed these wood species died as a result of allelochemical toxicity. While teak demonstrated the greatest degree of termite resistance, spruce and yellow pine were most palatable to termites. Generally, termites avoided feeding on the most resistant wood species, except for Peruvial walnut, which killed most termites despite sustaining heavy damage.

Do you know how resistant the lumber in your home is to termite attack?