Abstract
A new trihaloimidazole derivative S-377 [1-(4-chlorobutyloxymethyl)-2, 4, 5-trichloro-imidazole] showed high insecticidal activities against pyrethroid-resistant (O-colony) German cockroach Blattella germanica and physical and chemical properties appropriate for an active ingredient of heating fumigant. Consequently, this compound presented remarkable lethal and knockdown efficacy, comparable to that of methoxadiazone and permethrin, against the O-colony by three types of heating fumigant formulation in wider chambers. As for the mode of actions, S-377 showed low inhibitory effect on acertylcholine esterase in the German cockroach. According to electrophysiological study, this compound induced bursts of spontaneous firing on the abdominal nerve cord of German cockroaches, which continued for 60 min after the application. These results suggests that the central nervous system of German cockroaches is affected by this compound in a certain manner different from that of organophosphates, carbamates and pyrethroids. At least three possible modes of action have been suggested: (1) inhibitory actions on inhibitory systems, (2) inhibitory action on inactivating system of Na channels in a manner different from that of pyrethroids, and (3) facilitation of the excitatory system including the stimulation of excitatory synaptic transmission.
