Projuvenoids: synthesis and biological evaluation of sulfenylated, sulfinylated, and sulfonylated carbamates.

Applying the proinsecticide principle developed earlier for neurotoxic carbamate insecticides, a series of new N-sulfenylated, N-sulfinylated, and N-sulfonylated derivatives of fenoxycarb were synthesized and evaluated for juvenile hormone mimicking activity. Laboratory evaluations of the compounds using Pieris brassicae and Sitophilus oryzae, as well as field experiments using Bemisia tabaci, showed that several symmetrical biscarbamates with either a sulfenyl or sulfinyl bridge possessed higher activity than the parent carbamate. From the unsymmetrical compounds containing biologically inert derivatizing moieties, one of the sulfenylated biscarbamates also showed improved activity against P. brassicae. The changes in the biological activity of the sulfur-containing derivatives compared to that of the parent compound are attributed to the modified physicochemical characteristics, i.e., increased lipophilicity facilitating penetration, transport, as well as protection of the compound from metabolism.

Cinnamyl derivatives and monoterpenoids as nonspecific ovipositional deterrents of the onion fly.

Laboratory dose-response choice tests and discriminate-dosage bioassays revealed wide variation in the effectiveness of cinnamyl, cinnamoyl, monoterpene, and phenethyl alcohol derivatives as ovipositional deterrents toDelia antiqua (Meigen), the onion fly. (E)-Cinnamic acids were not detectably deterrent. When formulated in particles of polyethylene glycol, (E)-cinnamaldehyde had a BR90 (concentration eliciting 90% deterrency) of 1.0% and (E)-4-methoxycinnamaldehyde had a BR90 of 0.38%. Among nine monoterpenoids tested,p-cymene was inactive, citronellal had a BR90 of 3.7%, and terpinene-4-ol had a BR90 of 0.46%. Para-substituted phenethyl alcohols gave increasing deterrence in the order: -NO2, CH3O-, -Cl, -CH3, -H. Wide varieties of structures were deterrent: C-8 to C-13, intermediate in polarity, and possessing either oxygen-containing or nitrile functional groups. The air concentration of (E)-cinnamaldehyde at its BR90 was 1.7 ng/ml. This relatively high concentration, the diversity in deterrent structures, and the lack of differences in deterrency among positional and optical isomers suggest that ovipositional deterrency in onion flies is mediated by receptors broadly tuned for detecting phenylpropenoid, phenolic, monoterpenoid, and perhaps other classes of allelochemicals.

A rapid method for the evaluation of nerve conduction blocking compounds.

A simple and easily accessible cockroach nerve preparation is described. Afferent potentials elicited by electric stimulation of the cercus showed remarkable stability, providing a fairly adequate background for pharmacological experimentation. Type I and type II pyrethroids were tested on the nerve preparation, and the results were compared with toxicity data obtained on the same species. Blockade of nerve conduction showed positive correlation (r = 0.804) with lethal effects. The preparation would be useful for determining neuronal point of attack of test compounds and the study of pyrethroids.