Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 12, 2000
Publication Date: N/A
Interpretive Summary: The eastern subterranean termite, Reticulitermes flavipes, is the predominant pest termite found throughout the eastern United States. Subterranean termite damage and control efforts cost Americans an estimated 2 to 5 billion dollars annually. Although insecticides have been used to control subterranean termites for decades, very little research has been conducted 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, ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology, in cooperation with the Forest Service, have examined the relationship between insecticide detoxification and susceptibility in two colonies of eastern subterranean termite. They found differences in susceptibility but not metabolism of the common termiticide active ingredient, permethrin. Furthermore, the termites were observed to be highly susceptible to the insecticide synergist, piperonyl butoxide.
Technical Abstract: Toxicity and metabolism of t-permethrin were evaluated in two colonies of the eastern subterranean termite, Reticulitermes flavipes, collected in Gainesville, Florida. The UF colony (LC50 1.86 micro grams/vial) was 2-fol more tolerant of t-permethrin than the ARS colony (LC50 0.89 micro grams/vial) at the LC50. The synergists piperonyl butoxide and S,S,S- tributylphosphorotrithioate increased t-permethrin toxicity 4- and 3-fold (at the LC50) in both colonies, respectively. Despite differences in t- permethrin susceptibility, microsomal monooxygenase activities toward surrogate substrates(aldrin epoxidase, and methoxyresorufin O-demethylase) and cytochrome P450 content were not significantly different between the colonies. Moreover, no significant differences in qualitative and quantitative metabolism of [14C]t-permethrin were observed between the UF and ARS colonies for three enzyme sources (microsomal monooxygenase, microsomal esterase, and cytosolic esterase). Based on in vitro metabolis assays, the major detoxification route of t-permethrin in the UF and ARS termite colonies was hydrolysis catalyzed by microsomal esterases.