Diflubenzuron Hazards to Fish, Wildlife, and Invertebrates A Synoptic Review

Diflubenzuron (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea), also known as dimilin, is a potent broad-spectrum insect growth regulator that interferes with chitin synthesis at time of molting and is effective in controlling immature stages of insects. Diflubenzuron was approved for domestic use in 1976 to control gypsy moth (Lyrnantria dispar), and in 1979 against the cotton boll weevil (Anthonamus grandis). By 1989 this compound was also registered for domestic use against mosquitos, forest Lepidoptera, mushroom flies, and leaf-eating insect pests of citrus, woody ornamentals, vegetables, and fruit. Diflubenzuron seldom persists for more than a few days in soil and water. When used properly in forest management, it is unlikely to be leached into ground water from the application site. Degradation in water and soil is most rapid when small particle formulations are applied; microorganisms are abundant; and at elevated pH, temperature, and organic loading. Chemical and biological processes initially yield 2,6-difluorobenzoic acid and 4-chlorophenylurea. Soil degradation processes and plant and animal metabolism involve further conversion of these compounds to 2,6-difluorobenzamide and 4-chloroanaline. Ultimately, the end products are either conjugated into mostly water soluble products or biologically methylated.