Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 1998
Publication Date: N/A
Interpretive Summary: The dark southern subterranean termite, Reticulitermes virginicus, is an economically important pest termite found throughout the eastern United States. Subterranean termite damage and control efforts cost Americans an estimated 2 billion dollars annually. Although insecticides have been used to control subterranean termites for decades, very little research has been nconducted on their detoxification systems. As a result of the loss of the organochlorine termiticides in 1988 and the short lived nature of the insecticides that have replaced them termite control failures have begun to increase. Therefore, scientists at the Center for Medical, Agricultural and Veterinary Entomology, Auburn University and the U.S. Forest Service have characterized the oxidative detoxification system in the dark southern subterranean termite. They identified an active detoxification system that was variable among different termite colonies. This research will serve as starting point for future research concerned with termite detoxificatio systems.
Technical Abstract: Microsomal oxidases were characterized using surrogate substrates in the economically important dark southern subterranean termite, Reticulitermes virginicus (Banks). Aldrin epoxidase activity required NADPH and was inhibited by carbon monoxide and piperonyl butoxide (I50 = 4.72 ñ0.31 x 10-6 M) indicating that the enzyme(s) involved was a cytochrome P450 monooxygenase. Aldrin epoxidase activity was highest at 22o C and pH 7.2. Also, the activity was linear up to 0.5 mg of protein per incubate and increased with reaction time up to 15 minutes. Although neither substrate nor cofactor was found to be a limiting factor, aldrin epoxidase activity failed to produce a linear response with respect to time at temperatures above 22o C indicating enzyme inhibition. While increased incubation temperature above 22o C resulted in decreased aldrin epoxidase activity, similar heat treatments did not result in a concomitant increase in cytochrome P420. Significant variation (3.7-fold) in aldrin epoxidase activity was observed among seven R. virginicus colonies collected from different locations in Florida and Alabama.