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Efficacy of fumigators in the field against insecticide-resistant German cockroaches (Blattella germanica)

Miyaji, R., Yoshida, S., Matsubara, A., Hasegawa, T.
Acta horticulturae 2017 no.1169 pp. 53-58
Blattella germanica, insecticide resistance, mortality, permethrin, pest control, propoxur, pyrethrins, restaurants, surveys, topical application
The development of resistance to insecticides represents a serious issue in the field of pest control. Several studies have reported the development of pyrethroid resistance in the German cockroach (Blattella germanica). Populations that survive after insecticide treatments are considered to have acquired resistance. As a consequence, difficulties are now associated with exterminating the German cockroach using commercial insecticides. We herein report the efficacy of Earth Red® fumigators in the field. In the present study, we investigated the efficacy of these fumigators and the permethrin resistance ratio (RR) of German cockroaches in a number of restaurants in Tokyo. Efficacy was evaluated by surveying the number of cockroaches captured using the glue trap GOKIBURI HOIHOI® before and after the fumigator treatment. The permethrin RR was assessed by topical application on the captured population. The cockroaches captured in all restaurants treated had developed permethrin resistance, with a RR that was approximately 50- to 200-fold. However, even in restaurants with resistant cockroaches, Earth Red W® and Earth Red Pro alpha® containing d,d-T-cyphenothrin, a pyrethroid, and metoxadiazone, a non-pyrethroid insecticide, were very effective. This result was attributed to d,d-T-cyphenothrin exerting a stronger flushing-out effect, which drove cockroaches out of their hiding places more effectively than permethrin, and also to the combined effects of d,d-T-cyphenothrin and the non-pyrethroid insecticide metoxadiazone. This combination caused high lethality. Propoxur also enhanced the flushing-out effect. Although pyrethroids also exerted the flushing-out effect, the combination of pyrethroids and propoxur enhanced this effect.