Laboratory Tests with Encapsulated Diazinon Residual Spray, 1983

Abstract

Abstract A series of tests were conducted in the laboratory to compare the residual effectiveness of encapsulated diazinon with residues remaining from application of diazinon and malathion emulsion sprays. Whatman’s 9-cm No. 1 filter paper was used for a porous substance and glass slides measuring 3.25 by 4 in. provided an impermeable substrate for the tests. Filter paper was contained in lids of 10-cm plastic petri dishes and glass slides were handled directly. Sprays were applied from a 0.5-gal Namco compression sprayer through a fan nozzle (no. 800067). The spray tank was connected by a flexible hose to an air line equipped with a regulator to maintain a constant nozzle pressure of 20 lb/in2. Application rate was calibrated to spray approximately 1 gal/1,0002 when the nozzle was moved systematically over treatment substrates resting in a defined area of our laboratory spray compartment. Four spray replications were made for each concentration used for each test species for aging dates of 1, 7, 14, and 28 days required for spray residues. Appropriate control samples of each species were included in the test design. Twenty-five specimens of each species were contained in 7.5-cm diam fluon-treated glass cylinders to keep insects on treated surfaces of treatments in each replication. A filter paper cover was provided as needed to prevent escape of flying insects. After an exposure of 2 h to treted surfaces, test insects were placed in fresh containers with a small portion of food material. Mortalities were recorded 7 days after initial exposure to treatments. Residues on treated filter paper and glass slides were aged in a test room maintained at 80°F and 50 to 60% RH. Spray was applied and insects were exposed to treatments in rooms kept at 75°F. Test insects reared in the laboratory were mature larvae of the warehouse beetle and young adults of the other species. Percentages given in the tabulation of results were corrected for natural mortality, but few insects died in control samples.