The chlorinated diphyenyl compound, Diflubenzuron, is an insect growth regulator. Diflubenzuron can be found as a soluble concentrate, flowable concentrate, wettable powder, All wettable powder diflubenzuron products are classified as a Restricted Use Pesticide, meaning for certified applicator use only
Diflubenzuron works by preventing the formation of chitin, a molecule necessary to the formation of an insect’s cuticle or outer shell. Insects that absorb a dose of diflubenzuron cannot form their protective outer shell and die during molting. It is particularly effective against insect larva, but also acts as an ovicide, killing insect eggs
According to industry tests, diflubenzuron does not pose a high risk of acute toxicity to mammals. The oral LD50 (dose needed to kill 50% of the animals tested) is greater than 4.64 g/kg in rats and mice and the dermal LD50 is 4.64 g/kg in rabbits. However, EPA has given it a toxicity class III rating (out of a scale of I to IV, I being the highest toxicity class) with the signal word CAUTION, because it does cause skin and eye irritation.
Methemoglobinemia and sulphemoglobinemia, indicating an impairment of the oxygen carrying capacity of the blood, were seen in many studies (acute, sub-acute, sub chronic, and chronic). Moderate amounts of diflubenzuron fed to day-old ducks for 90 days showed decreased testosterone levels after 42 days (EXTOXNET 2001). Also, 2.5 parts per million of diflubenzuron in a diet fed to growing chickens was shown to depress testosterone levels.
Diflubenzuron has not been found to be mutagenic in short-term tests. However, when halogenated compounds (molecules containing either chlorine, bromine, fluorine or iodine) like diflubenzuron are tested in short-term tests, results of ten correlate poorly with carcinogenicity in animal assays.
The major environmental hazard posed by diflubenzuron is its non-selective toxicity to insects, including beneficials like the parasitic wasp. Diflubenzuron is also highly toxic to both aquatic invertebrates and crustaceans because they are both chitin producers. The LC50 (concentration needed to kill 50% of the test population) for the common water-flea is 1.5 ppb (parts per billion) and blue crab reproduction is impaired at even lower concentrations with an LC50 of only 0.5ppb.