This report includes the determination of activity and possible mode of action for a group of potential new insecticides. The biological screening procedure was developed using Drosophila melanogaster as the test organism while Musca domestica was used for mode of action assays. The percent kill for each compound is based on the number of eggs placed on media containing the insecticide minus the number of adults enclosed as compared to the control media reared flies. Observations were made on all stages from eggs through adults to determine time of death and if any malformations were present. These observations aided in the mode of action studies as did preciously published work on diflurbenzuron. The mode of action studies encompassed chitin synthesis, chitin breakdown and DNA synthesis. Cuticle deposition was determined gravimetrically on pupal instar reared on media with and without DOWCO 416. Chitin synthesis and DNA synthesis were followed by measuring the incorporation of radiolabeled precursors by pupal instars reared on media with and without DOWCO 416. Chitin breakdown was followed through the measurement of chitinase activity spectrophotometrically on all stages of larvae which were reared on media with and without DOWCO 416. Direct inhibition of chitinase was investigated by incubation of the purified chitinase from Staphlycoccus griseus with varying concentrations of the test compound
