Quantitative structure-activity relationships of benzoylphenylurea larvicides

The larvicidal activity of benzoylphenylureas with various multiple substitution patterns at the anilide moiety including chlorfluazuron and teflubenzuron was estimated against the rice stem borer, Chilo suppressalis , under conditions in which the oxidative metabolism was eliminated as far as possible by using piperonyl butoxide. The activity was quantitatively analyzed using physicochemical parameters of substituents at each of the anilide aromatic positions. The results indicated that the total hydrophobicity (with an optimum) and electron-withdrawing ability of substituents are favorable to the activity. Small size of substituents was advantageous but the size effect was specific to their positions. The molecular mode of interaction with the possible receptor was suggested so that the compounds may recognize the possible receptor wall from the side of the vicinal pair of ortho and meta positions occupied by smaller substituents, and the receptor site corresponding to the ortho substituent is hydrophilic and constrained.