Toxicity of Orthene 75S to Pandora Moth, 1982

Abstract

Abstract Second stage pandora moths were collected near the north rim of the Grand Canyon in October 1982 and shipped on ponderosa pine foliage to Berkeley, Calif. Small ponderosa pine branches were clipped to fit into a 200-ml plastic specimen containers. The stem was inserted into a hole in the bottom of an inverted container, and 10 larvae were placed on the needles 24 h before spray application. Immediately before spray, a 15-cm diameter filter paper with a single radial slit was positioned around the stem and beneath the needles to catch any larvae falling during treatment. Spray was applied to individual branches at a volume equivalent of 9.35 liters/ha with a laboratory spray chamber during an exposure period of 60 sec. Orthene 75S was formulated in distilled water on the basis of weight per unit volume of the active ingredient. Eight concentrations were serially diluted from a concentrated source for each of three replications of the experiment. Two branches were sprayed with each concentration within a replication. A control group sprayed with water only was included with each replication. After treatment, the filter paper was removed, any fallen insects placed back on the branch, and the stem was clipped free of the treatment container. The branch and insects were placed within a clean specimen container, and the container was closed with a paper lid. Mortality was tallied after 7 days.