Exploratory Tests with Encapsulated Diazinon for Stored Product Insects, 1982

Abstract

Abstract A series of tests were made in the laboratory to compare the activity of encapsulated diazinon with diazinon and malathion emulsion spray. Sprays were applied from a 0.5-gal Namco compression sprayer through a fan nozzle (no.800067). Pressure was maintained at 20 lb/in2 by connecting the spray tank to an air supply equipped with a pressure regulator. Application rate was calibrated to apply approximately 1 gal/1,000 ft2 when the spray nozzle was moved systematically over a defined area in our laboratory spray application compartment. Before spray was applied directly onto insects, test specimens were anesthetized with CO2 and placed on filter paper held in 10-cm diam plastic petri dishes. Immediately after spray was applied, insects were transferred to clean holding jars with fresh food and held in these until mortalities were recorded. Whatman’s 9-cm No.l filter paper in 10-cm plastic petri dishes was sprayed in the same manner as insecticide was applied directly onto insects. Each treated paper was kept in the same dish throughout the test. In one test, insects were placed on wet paper immediately after spraying, in another the filter paper was left undisturbed to dry 3 h before exposing insects to the treatments, and in the last test the paper was dried at room temp for 24 h before placing insects on it. Insects were contained in 7.5-cm diam fluon-treated glass cylinders on treated paper 24 h before they were transferred to holding containers with fresh food. Sprays were applied and insects were exposed to treatments in a laboratory kept at 75°F; the postexposure test room was maintained at 80°F and 50 to 60% RH. Mortalities were recorded 7 days after initial exposure to the insecticide. Five replications of each treatment were made for each insecticide and appropriate controls were included for each test species. Twenty specimens of each species were exposed to treatments in each replication. Large black carpet beetle larvae and mature warehouse beetle larvae were used; the other laboratory-reared tests insects were young adults. Although few insects died in control samples, percentages given in the tabulation of results were corrected for natural mortality.