Abstract
The repellency of several insecticides to the final stage nymph, male and female of the Smoky-brown cockroach, Periplaneta fuliginosa was evaluated by counting their feces at the insecticide-treated corner in a test arena (radius 13cm, height 17cm). A nymph, male and female of the cockroach excreted mean number of 8.6, 9.6 and 9.3 spots of feces, respectively per day in the arena when they fed on mouse foods and water. When the arena was divided into four fan-shaped sections, 75%, 71% and 68% of the feces in each group were excreted in the harborage section, while the rest percentages were observed in food, water or blank (harborage-free) sections. When the harborages had been treated with 0.1% a.i. concentration of several kinds of insecticide, they excreted large numbers of feces in the insecticide-free harborage sections than in the insecticide-treated sections. In particular, after use of permethrin EC to the harborage, the number of feces in that section was much smaller and the mortality in 48 hours was very low due to the repellency against the insecticide. After the use of chlorpyrifos-methyl EC, diazinon EC or diazinon MC, the feces numbers were relatively large and the mortalities were high.
