Relationship between insecticidal and nerve activities of an imidacloprid-related nitromethylene compound and its N-alkyl congeners

An imidacloprid-related nitromethylene compound and its alkyl congeners at the imidazolidine NH site were prepared and their insecticidal and nerve-ex citatory and -blocking activities were measured. Tn the insecticidal test w ith the male adult American cockroach by the injection method, metabolic in hibitors, more or less, increased the activity of tested compounds. The NH mother compound was the most active among the nitromethylene compounds and was as active as imidacloprid under the synergistic conditions. The N-alkyl congeners were less active than the NH compound under the conditions. In b oth of the nerve excitatory and blocking activities measured with a central nerve cord of the American cockroach, the NH compound was the most active among the nitromethylene series compounds and was less active than imidaclo prid. A good correlation was not observed between the nerve activities. Qua ntitative analyses showed that the insecticidal activity measured with the metabolic inhibitors was better correlated with the nerve-blocking activity than with the nerve-excitatory activity. When factors of transport of the compounds within the insect body and/or interaction with target sites were considered separately by use of the hydrophobicity parameter, the correlati on with the nerve-blocking activity was significantly improved.