Flushing Effect and Knockdown Activity of Pyrethroids, 1988

Abstract

Abstract Relative flushing and knockdown times of synergized pyrethrins and a number of pyrethroid insecticides were evaluated; also, contrasts of EC and WP were made for some Type II pyrethroids. All testing was at a 0 . 1% (w/w) dilution in water. Harborages, constructed of tempered masonite (2.5” × 4”) and pine strips (3/16”) creating a small crack, were mounted vertically on 4” × 4” plywood bases. The harborage was placed in a plastic box with the inside, upper edge greased to prevent escape. Ten adults (≤ 2 wks old, 5 male + 5 non-gravid female) were introduced to this arena 24 h before testing, which always occured 4 - 6 h into the photophase of a 12:12 L:D photocycle. Test sprays were applied at the rate of 1 gal/1000 ft2 using a spray tower fitted with a flat fan nozzle (Spraying System Tee-Jet 8001E) at a constant pressure of 25 psi. The harborage, containing test insects, was positioned beneath the spray arm of the spray tower so that the harborage opening was parallel to the fan spray pattern. As the nozzle passed over the harborage, the sprayer delivered the treatment to the insects within. Immediately after being sprayed, the harborage was returned to the box for 1 h of observation. Each treatment was replicated twelve times (3 blocks of 4 replicates). Time (min) necessary to flush or knockdown 50% of the insects was compared among treatments. If 50% of the cockroaches were not flushed within the 1 h observation period, flush or knockdown time was defined as 100 min to incorporate individual replicates whose response was >60 min with others in the same treatment that were >60 min. Data analysis was with one-way ANOVA and means separation with LSD (a = 0.05)