Flushing Activity of Insecticides, 1991

Abstract

Abstract Laboratory tests were conducted to determine comparative flushing activity against adult German cockroaches among 19 treatments. Cockroach harborages were constructed by pairing two tempered masonite panels (4 inch x 2.5 inch) using 0.375-inch pine strips to create a crack between the two panels. This harborage was mounted (vertically) on a 0.25-inch pine base (4 inch X 4 inch). This completed harborage assembly was placed inside of a plastic box (7.5 inch x 5.5 inch X 4 inch) so only the open end of the harborage faced up. The upper, inside edge of the plastic box was lightly coated with a petrolatum-mineral oil mixture to prevent escape of test insects. Ten adults (s 2 wks old; 5 male and 5 nongravid female) were introduced to the box (equipped with a harborage unit and water-wick) 18 to 24 h before testing. Testing was conducted 4-6 h into the photophase of a 12:12 (L:D) photoperiod. The test insecticides were applied using a spray tower apparatus with a mechanized nozzle assembly which travels along a linear track within the spray chamber. A stainless steel nozzle tip, Spraying Systems Tee-Jet 8001E (flat, fan spray pattern), was used for all applications. The tower was calibrated to deliver 1 gal of finished spray per 1000 ft2 (0.95 ml per 232 cm2) of horizontal surface at 25 psi. The harborage containing the test insects was removed from the plastic box and placed beneath the spray arm of the spray tower, with the open end of the harborage positioned so that it was parallel with the fan spray pattern. As the spray arm passed over the harborage, the sprayer was activated to deliver the treatment to the test insects within the harborage. Immediately following the spray treatment, the harborage was returned to the plastic box for observations. The number of test insects that were flushed from the harborage at various time intervals (min;s) was recorded, as was the number of insects that were subsequently knocked down. Regression analysis of the resulting probit percentage of flushing vs. log10 of time was utilized to estimate the FT^ values. Mortality at 48 h after exposure was analyzed by ANOVA.