Evaluation of the Flushing Effect and Knockdown Activity of Various Insecticide Treatments, 1986

Abstract

Abstract A laboratory test procedure was developed to assess the relative flushing effect and knockdown activity of Dursban 4E (44.2% chlorpyrifos), XRM-4322 (44.2% chlorpyrifos, 4.4% pyrethrins, 8.8% piperonyl butoxide), Decis EC (5% deltamethrin), and Demon WP (40.0% cypermethrin). Plain water was included in the comparison as a control. Cockroach harborage was constructed from tempered masonite (4 × 4 inch) and pine strips (yi6 inch), creating a small crack (open at 2 ends) within which the cockroaches could hide. This harborage was placed sideways upon a plastic pedestal (3 cm high) within a plastic box (7 × 5 × 3.5 inch). The inside upper edge of the plastic box was greased (petrolatum-mineral oil mixture) to prevent escape. Ten adults (≤2 wk old, 5 male and 5 nongravid female) were introduced to the completed arena 24 h before testing, which always occurred 4-6 h into the photophase of 12:12 (L:D) photocycle. Test sprays were applied at the rate of 1 gal/1000 sq ft 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. When treated, the harborage containing the test insects was removed from the plastic box and placed within the spray tower so that an open end of the harborage was positioned beneath the spray arm, parallel with the fan spray pattern. As the spray arm passed over the harborage, the sprayer was activated briefly (<1 s) to deliver the treatment to the test insects within. Immediately after being sprayed, the harborage was returned to the plastic box for 1 h of observation. Each treatment was replicated 5 times. The times necessary to flush (FT) or knockdown (KT) 50 and 90% of the test insects were the variables compared between the treatments. If, for example, 50% of the test insects were not flushed within the 1-h observation period, the time necessary was then defined as 100 min for ease of analysis. This conversion allowed for incorporation of individual replicates for which response was >60 min when others in the same treatment were ≤60 min.