QUANTITATIVE STRUCTURE-ACTIVITY OF INSECT GROWTH-REGULATORS .9. QUANTITATIVE STRUCTURE-ACTIVITY ANALYSIS OF LARVICIDAL 1-(SUBSTITUTED BENZOYL)-2-BENZOYL-1-TERT-BUTYLHYDRAZINES AGAINST CHILO-SUPPRESSALIS

The larvicidal activity of a number of 1-(substituted benzoyl)-2-benzo yl-1-tertbutylhydrazines against the rice stem borer (Chilo suppressal is Walk.) was measured. Variations in the activity were examined quant itatively using physicochemical substituent and molecular parameters a nd regression analysis. The results indicated that the molecular hydro phobicity and the electron-withdrawing inductive/field effect of ortho substituents are favourable to larvicidal activity. The bulkiness of substituents at the meta and para positions was unfavourable to activi ty, substitution at the para position being more unfavourable than tha t at the meta position in terms of van der Waals' volume. The 2,3-, 2, 5- and 2,6-disubstitution patterns were also unfavourable to activity. Reductions in larvicidal activity caused by the 2,6-, 2,3,5- and 2,3, 4,5-substitutions were greater than those induced by the 2,3- and 2,5- disubstitutions. When the sum of contributions from favourable effects is greater than that from unfavourable effects, the larvicidal activi ty is expected to be superior to that of the unsubstituted compound.