Ovicidal and larvicidal structure-activity relationships of benzoylureas on the house fly (Musca domestica)

Abstract

Benzoylureas are insecticidal compounds interfering with chitin synthesis. A number of benzoylureas, with variations in lipophilic properties, were tested for their larvicidal and ovicidal activities on Musca domestica. The larvicidal activities were tested by mixing the compounds with the larval medium. The ovicidal activities were assessed either by feeding or by injecting female adults and resulted in nonemergence of the eggs, though the embryos seemed to be fully developed. A significant correlation (P = 0.02) was found between ovicidal activity after adult feeding and ovicidal activity after injection. Correlation of the activities by means of a physical chemical parameter revealed that ovicidal activity after injection was the basic activity in both ovicidal activity by adult feeding as well as larvicidal activity by feeding. However, in either case this activity was coupled to a lipophilic parameter (expressed as π in the octanol/water system). Optimum π-values for ovicidal activity after adult feeding or for the larvicidal activity were 1.0 and 1.5, respectively. It is likely that at increasing lipophilicity of the compounds above the optimum values, the gut wall becomes an important barrier but that the activity at the target site is not affected. At decreasing lipophilicity the activity at the target site probably also decreases.