Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/1998
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Although insecticides have been used for decades against subterranean termites, very little is known about their detoxication enzyme systems. However, recent introduction of the Formosan subterranean termite into the United States, EPA withdrawal of organochlorine termiticides and growing public concern have contributed to an urgent interest in understanding subterranean termite biology more thoroughly. We characterized microsomal oxidases in Reticulitermes virginicus workers and soldiers collected from seven locations in Florida and Alabama. Aldrin epoxidase activity required the cofactor NADPH, and was inhibited by carbon monoxide and piperonyl butoxide, a well-known cytochrome P450 monooxygenase inhibitor. These data indicate that aldrin epoxidation was catalyzed by 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 protein per incubate and increased with reaction time up to 15 minutes. Inhibition of aldrin epoxidase activity occurred above 22o C indicating temperature sensitivity. While increased incubation temperature above 22oC resulted in decreased aldrin epoxidase activity, similar heat treatments did not result in a concomitant increase in cytochrome P420 (degraded cytochrome P450). Surprisingly, significant variation (3.7-fold) in aldrin epoxidase activity was observed among the seven Reticulitermes virginicus colonies collected from sites in Florida and Alabama. Whether these differences represent inherent variation among this species, stage-dependent or other developmental effects, or a direct response to environmental factors (i.e. enzyme induction) is not known.