Laboratory performance and pharmacokinetics of the benzoylphenylurea noviflumuron in eastern subterranean termites (Isoptera: Rhinotermitidae)

Abstract

A benzoylphenylurea insect growth regulator with the common name noviflumuron was evaluated for use as a baiting toxicant against the eastern subterranean termite, Reticulitermes flavipes (Kollar). Noviflumuron demonstrated significantly greater potency and faster speed of action compared with the commercial standard hexaflumuron. In addition, noviflumuron was not a feeding deterrent on filter paper at concentrations of up to 10,000 ppm. The rates of uptake, clearance, and insect-to-insect transfer of [14C] noviflumuron were measured in R. flavipes in laboratory assays and compared with those previously reported for [14C] hexaflumuron. Under a continuous exposure regime, the uptake profile for noviflumuron was similar to that for hexaflumuron, although the time period of maximal uptake was shorter for noviflumuron. Noviflumuron was cleared from termites in a first order process with a half-life of ≈29 d, whereas the half-life of hexaflumuron was much shorter (8-9 d). Noviflumuron was efficiently transferred from treated to untreated termites by trophallaxis via kinetics similar to those reported for hexaflumuron; however, the systemic dose of noviflumuron required to result in toxicity of R. flavipes was found to be at least two- to three-fold less than that of hexaflumuron. The faster activity of noviflumuron compared with hexaflumuron in R. flavipes can be at least partially explained by the combination of slower clearance and greater intrinsic activity.