Comparative Effects of Two Chitin Synthesis Inhibitors, Hexaflumuron and Lufenuron, in a Bait Matrix Against Subterranean Termites (Isoptera: Rhinotermitidae)

Lethality, molting inhibitory effects, and feeding deterrence of 2 chitin synthesis inhibitors, hexaflumuron and lufenuron, were studied in a laboratory choice test using wood sawdust as feeding medium. Feeding deterrence of hexaflumuron in sawdust medium was lower than that observed in a previous study in which hexaflumuron-impregnated wooden blocks were used. The concentration threshold of hexaflumuron for feeding deterrence is high [>8,000 ppm for Coptotemes formosanus Shiraki, and >4,000 ppm for Reticulitermes flavipes (Kollar)], whereas ≈100% mortality was recorded 9 wk after exposure even at the lowest concentrations tested (125 ppm for C. formosanus and 31.3 ppm for R. flavipes). Feeding deterrence of lufenuron was observed at lower concentration intervals (1,000-2,000 ppm and 50-100 ppm for C. formosanus and R. flavipes, respectively) than hexaflumuron, but baits treated with the nondeterrent concentrations of lufenuron caused only 50-80% mortality. even after 9 wk of exposure. The overall potential of lufenuron as a bait toxicant is less than that of hexaflumuron.