Efficacy of Insecticides for German Cockroach Control, 1986 and 1987

Abstract

Abstract Laboratory tests were initiated to determine the relative efficacy and residual life against the German cockroach for the organophosphates azamethiophos (50% wettable powder), TD2222 (24.4% chlorpyrifos, microencapsulated), Dursban ME (11.7% chlorpyrifos, microencapsulated), and Dursban LO (41.5% chlorpyrifos). Test sprays of various concentrations were applied to 1-sq-ft (929 cm2) tempered masonite panels at the rate of 1 gal/1000 sq ft (3.78 ml/929 cm2) using a mechanized spray tower apparatus equipped with a stainless steel nozzle tip, Spraying Systems Tee-Jet 8001E, at a constant pressure of 25 psi. After treatment, panels were placed into vertical storage compartments (dark conditions) for residual aging. Residual agings evaluated varied from 3 to 12 mo for any one of the test insecticides. At the appropriate aging period, test insects were confined (continuous exposure) to the treated panel using 12.7-cm-diam plastic rings, lightly greased with a petrolatum-mineral oil mixture. Three or 4 exposure times were evaluated at each aging period for any insecticide. Initial exposure times ranged from 10 s to 5 h, but as the spray deposits aged these exposure times were increased to as long as 24 h for some treatments. The particular range of exposure times evaluated was selected to deliniate the critical periods necessary to produce acceptable mortalities. After exposure, insects were removed from the treated panel and placed in unteated holding jars, with food and water provided, for 48 h. Mortality counts were recorded at the end of the exposure time and at 24 and 48 h after the start of the exposure; the final mortality 48 h after the exposure is reported here. Six replicates were conducted for each exposure time, at each aging period, for each insecticide treatment. Each replication consisted of 10 cockroaches—5 adult males and 5 adult nongravid females.