Relationship between structure of several Azodrin insecticide homologues an their toxicities to house flies, tested by injection, infusion, topical application, and spray methods with and without synergist.

Abstract

Azodrin® insecticide (3-hydroxy-N-methyl- cis -crotonamide dimethyl phosphate) and 6 homologues were tested against Musca domestica L. by topical application, injection, infusion, and oil-spray methods with and/or without a synergist. Their observed toxicities obtained by different testing methods generally decreased from low to high homologues. When the results obtained by topical application and injection methods are compared on the same basis, the difference in toxicities is about 340 times between-NH2 and -NHC8H17 homologues by topical application, and only 2.8 times (M ratio) by injection of flies pretreated with sesamex (synergist) This tremendous change of observed toxicity indicates that by injecting toxicants into flies pretreated with sesamex, the potential toxicity of compounds can be more fully indicated; however, some detoxication may still occur in the higher homologues. Since homologues of Azodrin insecticide are partitioned more favorably into water than into hexane, the decrease in toxicity by an infusion method, as compared with injection results, is more likely due to detoxication than to partition into lipids. Thus the difference in toxicity between infusion and injection methods would indicate the degree of instability of these compounds in house flies and should correlate with the degree of synergism. When the degree of synergism of Azodrin homologues was plotted against the LD50 ratio of infusion and injection on log-log scales, a straight-line relationship was obtained. Further study on the interaction between physical, chemical, and biological factors is necessary for a better understanding of the relationship between structure and activity.