Relationship between insecticidal and nerve-excitatory activities of imidacloprid and its alkylated congeners at the imidazolidine NH site

The insecticidal and nerve-excitatory activities of imidacloprid and its al kylated congeners on the imidazolidine NH site were measured. In the insect icidal activity against the green rice leafhopper measured in a spraying te st using rice seedlings, a few compounds with C3-alkyl groups were as activ e as imidacloprid. In the insecticidal test against the American cockroach by the injection method, the activity values were generally increased by th e use of metabolic inhibitors of oxidative degradation mechanisms. Under th ese conditions, all of the alkyl derivatives were less active than imidaclo prid, as shown by the nerve activity measured in the excised central nerve cords of American cockroaches. The higher the nerve activity the higher the insecticidal activity when the hydrophobic factors of the compounds were c onsidered separately. (C) 1998 Academic Press.