Laboratory Residual Dust Study for Brown Recluse Spider Control

Abstract

Abstract Two laboratory tests were conducted to evaluate the residual activity of 5 different dust formulations at different dosage rates. In test 1, dusts were applied to 2 different surfaces, masonite and the paper backing attached to Owens-Corning Fiberglass Building Insulation, while only masonite was used in test 2. Treatment consisted of spreading dust evenly over the masonite surface (4 inch × 4 inch × 1/4 inch) with a paint brush to an accuracy of 0.001 g. The dust was applied to the paper backing of insulation (4 inch × 4 inch) by placing it in a closed cylindrical container (7 inch × 6 3/4 inch diameter) and treating with a hand bulb duster. The duster was held horizontally with the nose in a hole at a height of 5 1/4 inches and pumped 2 to 3 times. The amount of dust applied was then measured and more was added as needed to an accuracy of 0.005 g. The application amounts were set to duplicate label rates if known. Treatments were allowed to age for 24 h. After 24 h, spiders were exposed to the treated surface for one hr before being transferred to an untreated surface. Test procedure consisted of placing one spider under a 10 oz plastic cup (7.1 square inches of treated surface) and then confined to an untreated surface for 48 h after treatment. Each treatment was replicated 5 times. Mortality counts were made at 1, 4, 8, 24, and 48 h. Tests were started at 1, 7 and 14 DAT. All mortality figures for this test are accumulative from the first observation (1 HOAT) for that particular date to conclusion of test on that date (48 HOAT). Spiders used in the test were collected from a natural habitat that had no prior insecticide treatment. Spiders were maintained in 1 oz plastic cups with food and water.