Repellency of insecticides against German cockroach, Blattella Germanica, observed by feces distribution in insecticide-treated harborages

Abstract

In a preliminary test, male German cockroach evacuated a mean number of 14 drops of feces and the female 11 drops per day, when they were maintained with water and dried mouse food. The feces were deposited at the circumference of the arena (radius 15cm, height 17cm, and area 706.5(cm)^2) in the case of absence of any harborages. In the harborage test, adult German cockroaches were maintained in the same arena with a harborage made of plywood panels, with water and mouse food. Light regimen was 14L : 10D, and the temperature was maintained at approximately 25℃ throughout the test period. When the arena was divided equally into four sections : water, food, insecticide-free harborage, and blank, 90% of the feces of five cockroaches both male and female was deposited in the harborage section, and the remaining 10% deposited in the other sections during a 2-day period. After treatment with 0.05% permethrin or propoxur on the surface of the harborages, the number of their feces dramatically decreased, and no cockroaches were killed within 24hrs. When harborages were treated with 0.05% micro-encapsulated fenitrothion and diazinon, the percentage of the number of the feces in the harborage section did not decrease markedly, and a majority of the cockroaches was killed. The distribution of German cockroach feces is indicative of the presence of aggregations. The presence of feces may serve as an indicator of the repellent qualities of cockroach control insecticides.