Relationship between Insecticidal and Nerve Activities of an Imidacloprid-related Nitromethylene Compound and Its <i>N</i>-Alkyl Congeners

Abstract

An imidacloprid-related nitromethylene compound and its alkyl congeners at the imidazolidine NH site were prepared and their insecticidal and nerve-excitatory and -blocking activities were measured. In the insecticidal test with the male adult American cockroach by the injection method, metabolic inhibitors, 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 both 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 imidacloprid.A good correlation was not observed between the nerve activities. Quantitative 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 correlation with the nerve-blocking activity was significantly improved.

Proneonicotinoid

“…Yamamoto et al demonstrated that 3N-methyl imidacloprid (15, RϭMe) was partly demethylated in vitro by a mixed function oxidase system. 36) In experiments with 3N-alkyl/allyl-imidacloprid and the nitromethylene analogues, 37,38) the introduction of these groups lowered the activity of the mother insecticides by more than 10 times in the injection test of the housefly (Musca domestica) (evaluated 1 hr after injection) and for the American cockroach (evaluated 24 hr after injection). On the other hand, in the measurement 4 days after the active ingredient was sprayed on rice plants, the 90% lethal dose of n-propyl, allyl and propargyl imidacloprid derivatives for green rice leafhoppers was as low as 0.32 ppm, comparable with that of the mother compound.…”

Insecticidal and Neuroblocking Activities in the American Cockroach (Periplaneta americana L.) of Mannich Bases of Nitromethylene Imidazolidine Neonicotinoids

“…NIA16388 (propargyl propyl benzenephosphonate; NIA), an inhibitor of the hydrolytic metabolism of a pyrethroid, tetramethrin, 12) was the same sample used in previous studies. [7][8][9][10] …”

“…[7][8][9][10] In short, various volumes (1-10 ml) of the methanol solution of each compound containing some amount of dimethyl sulfoxide (DMSO) were injected into the abdomen of the cockroach unless otherwise noted. Organic solvents alone in this range did not show any toxic effect.…”

“…[7][8][9][10] In brief, the abdominal central nerve cord of an adult male American cockroach was excised between the fourth and fifth ganglia. One of two bundles divided from the thoracic side of the nerve cord was tightly taken up with saline (210.4 mM of NaCl, 2.9 mM of KCl, 1.8 mM of CaCl 2 , 1.8 mM of Na 2 HPO 4 and 0.2 mM of KH 2 PO 4 ; pH 7.3) into a glass tube, in which a chlorinated silver wire was set as the electrode.…”

“…We examined the insecticidal activity of prodrug compounds 3 and 4 on injection into cockroaches and conducted neuroblocking measurements with excised nerve preparations of this insect. [7][8][9][10] MATERIALS AND METHODS…”