BIOLOGICAL-ACTIVITY OF PYRETHROID ANALOGS IN PYRETHROID-SUSCEPTIBLE AND PYRETHROID-RESISTANT TOBACCO BUDWORMS, HELIOTHIS-VIRESCENS (F)

The phenoxybenzyl moiety of conventional pyrethroids is a major site o f oxidative metabolism in resistant tobacco budworms, Heliothis viresc ens (F.). In this study, this group was replaced with known P450 monoo xygenase-inhibiting or oxidatively blocked groups. A variety of isomer s (1R/1S, cis/trans) of the resulting chrysanthemates were tested as i nsecticides or synergists against tobacco budworms that were insectici de-susceptible (LSU) or that expressed metabolic resistance to cyperme thrin (Pyr-R). A number of compounds with pentafluorophenyl, methylene dioxyphenyl, and propargyloxyphenyl groups were insecticidal, and acti vity was dependent on both geometric and stereochemical configuration of the acid moiety. Both traits and cis isomers of 1(R)-fenfluthrin, w hich contains a pentafluorophenyl group, suppressed resistance to cype rmethrin in Pyr-R insects, confirming that oxidative metabolism of the phenoxybenzyl moiety is a major mechanism of resistance in this strai n. Of the methylenedioxyphenyl compounds, 1R, trans, and cis isomers w ere tome and partially suppressed resistance in Pyr-R larvae. Similarl y, both trans and cis isomers of alpha(S),1(R)-propargyloxyphenyl-cont aining compounds were insecticidal. Finally, alpha(R),1(R)-cis-methyle nedioxyphenyl- and -propargyloxyphenyl-containing compounds were nonto xic but significantly enhanced toxicity of cypermethrin.