Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2007
Publication Date: 6/1/2007
Citation: Raina, A.K., Bland, J.M., Doolittle, M., Lax, A.R., Boopathy, R., Folkins, M. 2007. Effect of Orange Oil Extract on the Formosan Subterranean Termite (Isoptera: Rhinotermitidae). Journal of Economic Entomology 100(3):880-885.
Interpretive Summary: The Formosan subterranean termite (FST) is a major urban pest, causing damage to houses and live trees. Due to increasing restrictions on the use of conventional termiticides, attention is focused on finding safer alternative methods for termite management. Extract of citrus peel, referred to here as orange oil extract (OOE) is known to be toxic to several species of insects. We determined the effect of OOE on FST. In tight containers, OOE killed a very high proportion of termites. OOE mixed with sand prevented termites from tunneling through it. However, when the void of a test wall was treated with OOE, it did not prove very effective. Also when mixed with sand, OOE did not persist for more than three weeks. Being safe to humans and cheap, OOE may be used in combination with other control practices to manage subterranean termites.
Technical Abstract: The Formosan subterranean termite Coptotermes formosanus Shiraki, accidentally brought into the United States, has become a major urban pest, causing damage to structures and live trees. Due to increasing restrictions on the use of conventional termiticides, attention is focused on finding safer alternative methods for termite management. Oil from citrus peel, referred to here as orange oil extract (OOE), contains about 92% d-limonene, and is known to be toxic to several species of insects. In laboratory experiments, 96 and 68% termites were killed in five days when vapors from OOE at 5 ppm (v/v) were released from the top or bottom respectively, with termites held at the opposite end of a tight fitting plastic container. Apart from high mortality, workers exposed to vapor consumed significantly less filter paper than control. However, when termites were exposed to OOE vapor, even at 10 ppm, in the void of a model wall, there was very little mortality. Termites did not tunnel through glass tubes filled with sand treated with 0.2 or 0.4% OOE. Sand treated with OOE was extracted each week for eight weeks to determine the remaining amount of d-limonene. Results indicated that there was a sharp decline in the quantity of d-limonene during the first three weeks to a residual level that gradually decreased over the remaining time period. With a suitable method of application and in combination with other control practices, OOE can be effectively used for the control of subterranean termites.