MORTALITY OF BLATTELLA GERMANICA (L.) (BLATTODEA: BLATTELLIDAE) IN RELATION TO THE PERCENTAGE OF EXPOSURE TO PESTICIDES AND TYPE OF SURFACE, BEFORE AND AFTER WASHING

ABSTRACT Among the species of synanthropic cockroaches, the German cockroach, Blattella germanica (L., 1767) is the most important in terms of developing high populations in habitations. This study evaluated the mortality of B. germanica exposed to different areas treated with an equivalent amount of insecticides to verify the mortality caused by pesticides on smooth and rough surfaces, before and after washing. The experiments were carried out at the Departamento de Fitossanidade, UNESP/FCAV, Campus Jaboticabal, SP, Brazil. In the first experiment, the insecticide was applied to Petri dishes, with areas of exposure to the insecticide of 25, 50, 75 and 100%. The second application was performed by pressurized spraying on smooth and rough surfaces, which were then washed with detergent and water after treatment. The insecticides used were cypermethrin (Cynoff 400 AM) 2.5 c.p. g/L, deltamethrin (250 Deltagard WG) 1.0 c.p. g/L; lambda-cyhalothrin (Icon 5 EC) c.p. 5.0 mL/L and an untreated plot (control). In the first experiment, 5 adult insects were enclosed for fifteen minutes, while 10 were enclosed in the second experiment. Mortality evaluations were performed at 0, 1, 2, 4, 24, 48 and 72 hours after confinement. It was found that the insecticides used in 50%, 75% and 100% of the area resulted in a high mortality of B. germanica. The insecticides cypermethrin, deltamethrin and lambda-cyhalothrin proved efficient for the control of B. germanica, before the washing of the smooth surface. The effectiveness of these insecticides was greater on a smooth surface than a rough one. After washing, the effectiveness was lower for both surfaces.