Hexaflumuron is the active ingredient of the Sentricon Termite Colony Elimination System. A compound similar to hexaflumuron, noviflumuron, has been tested in the field and laboratory and shown to be more active than hexaflumuron, both in terms of dosage required to eliminate a termite colony, and in the time required for colony elimination. To investigate if differences in the rate of uptake, clearance, insect to insect transfer, or metabolism of noviflumuron can explain why this compound is faster and more active than hexaflumuron, we conducted a series of experiments to measure these kinetic parameters in eastern subterranean termites. Termites were fed cellulose containing either [14C] noviflumuron or [14C] hexaflumuron and the above pharmacokinetic parameters were measured. Noviflumuron was found to be more toxic and faster acting than hexaflumuron in all the experiments. Internal uptake of noviflumuron is generally less than hexaflumuron, especially at the higher diet concentrations. Hexaflumuron is cleared from termites in a first order process with a half-life of 8-9 days, whereas half life of noviflumuron in termites is much longer, 29 - 191 days depending on the initial concentration fed to the insects. Both compounds are efficiently transferred from treated to untreated termites by trophallaxis, with similar kinetics. The dose of noviflumuron required internally in termites to result in toxicity is at least 5 to 6 times less than that required of hexaflumuron. Thus, noviflumuron is either more active at the target site, and/or has much greater availability to reach the target site than hexaflumuron. In any case, it is clear that the faster activity of noviflumuron over hexaflumuron comes about due, at least in part, to a combination of increased toxicity of noviflumuron at a given internal dose, and to its slower clearance from the body of termites.
Species 1: Isoptera Rhinotermitidae Reticulitermes flavipes (eastern subterranean termite)
Keywords: noviflumuron, Sentricon Termite Colony Elimination System
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