COMPARATIVE EFFECTS OF 2 CHITIN SYNTHESIS INHIBITORS, HEXAFLUMURON AND LUFENURON, IN A BAIT MATRIX AGAINST SUBTERRANEAN TERMITES (ISOPTERA,RHINOTERMITIDAE)

Lethality, molting inhibitory effects, and feeding deterrence of 2 chi tin 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 obse rved in a previous study in which hexaflumuron-impregnated wooden bloc ks were used. Tile concentration threshold of hexaflumuron for feeding deterrence is high [>8,000 ppm for Coptotermes formosanus Shiraki, an d >4,000 ppm for Reticulitermes flavipes (Kollar)], whereas approximat e to 100% mortality was recorded 9 wk after exposure even at the lowes t concentrations tested (125 ppm for C. formosanus and 31.3 ppm for R. flavipes). Feeding deterrence of lufenuron was observed at lower conc entration intervals (1,000-2,000 ppm and 50-100 ppm for C. formosanus and R. flavipes, respectively) than hexaflumuron, but baits treated wi th the nondeterrent concentrations of lufenuron caused only 50-80% mor tality, even after 9 wk of exposure. The overall potential of lufenuro n as a bait toxicant is less than that of hexaflumuron.