Efficacy of Several Formulations of Permethrin and Cypermethrin on the German Cockroach, 1981

Abstract

Abstract The contact toxicity of three formulations (WP, EC, and encapsulated) each of permethrin and cypermethrin was investigated to determine the most effective formulation and rate, the contact time required to produce mortality, and the residual activity up to 3 months against the German cockroach. Dilutions were prepared to produce rates of 0.25 and 0.125% for each of the formulations tested. Masonite panels cut to 1 ft2 (929 cm2) were treated. A spray tower apparatus with a mechanized conveyor belt was used to apply the treatments. A stainless steel nozzle, Spraying Systems Tee-jet 8001, was used during application. The tower was calibrated such that each treatment was applied at 1 gal/1,000 ft2 (3.78 ml/929 cm2). Treated panels were placed in storage compartments for aging. After treatment, German cockroaches were exposed to deposits aged 0 day, 2 weeks, and 1, 2, and 3 months. Three bioassays (lengths of exposures to treated surface) were conducted at each of the aging periods for each of the formulations tested. Bioassays ranged from 5 sec to 48 h and were determined prior to testing to delineate the critical time periods necessary to produce acceptable mortalities. After exposure, insects were removed from the treated surface and placed in untreated holding jars for 48 h. Food and water were provided. Mortality counts were made at 24 and 48 h. The average percent mortality for all replicates was determined using Abbott’s formula. Three replicates were used for each exposure period. Each replication consisted of 10 cockroaches, 5 males, and 5 females.