Insecticidal Activity of Novel Trihaloimidazole Derivatives against a Wild Colony of German Cockroaches (Blattella germanica)

Abstract

Structure-activity relationships of novel 1-alkoxymethyl-2, 4, 5-trihaloimidazole compounds against a wild colony of German cockroaches resistant to pyrethroids (O-colony) are reported. Among them, 1-methoxymethyl-2-bromo-4, 5-dichloroimidazole and 1-isopropoxymethyl-2-bromo-4, 5-dichloroimidazole were very effective by a filter paper contact method. The variation in insecticidal activity is shown to be related to the length and branching of the alkyl chain of the 1-substituents. Above all, 1-(4-bromobutoxymethyl)-2-bromo-4, 5-dichloroimidazole and l-(4-bromo/chlorobutoxymethyl)-2, 4, 5-trichloroimidazole exhibited low acute oral toxicity to mice and good activity by a heating fumigant test, representing one of the practical applications. The trihaloimidazole derivatives had almost two-fold higher activity against O-colony insects than against the susceptible strain.