Abstract
Insecticidal activity of the feces excreted from hydramethylnon bait-fed cockroaches was evaluated in three species and four strains of cockroaches indigenous to Japan. Cockroaches used for the test were the Yoken, Ohsaka, Shibuya and Toshima strains of Blattela germanica, Periplaneta americana and P. fuliginosa. Hydramethylnon-contained bait, male adult cockroaches, water and harborage were placed in plastic cups. Three or 4 days later when all the male cockroaches had died, the dead insects and hydramethylnon-contained bait were removed, and the feces were left in the cups. Then 1-2 instar nymphs, male and female adult cockroaches and untreated rat food were placed in each cup. As a control group, food was placed instead of hydramethylnon-contained bait, i. e., male adult cockroaches, untreated rat food, water and harborage were placed in plastic cups. Corrected cumulative mortality for each test group was calculated by the Abott method and compared with the cumulative mortality of control group. Corrected cumulative mortality of the Yoken strain of B. germanica for the experimental period of 18 days were 82.5% for adult males, 65.0% for adult females and 48.6% for 1-2 instar nymphs. Among the other field-captured strains, corrected cumulative mortality for adult females in the Shibuya strain, 1-2 instar nymphs in both the Ohsaka and Toshima strains were higher than that for the corresponding stage and/or sex in the Yoken strain. Corrected cumulative mortality of P. americana for the experimental period of 29 days were 78.7% for adult males, 7.6% for adult females and 70.9% for 1-2 instar nymphs. Corrected cumulative mortality of P. fuliginosa for the experimental period of 29 days were 23.4% for adult males, 50.0% for adult females and 76.7% for 1-2 instar nymphs. Although the mortality for adult females P. americana was low, our results demonstrated that hydramethylnon has a secondary kill effect for B. germanica, P. americana and P. fuliginosa through the feces excreted by hydramethylnon-fed cockroaches.
