Diflubenzuron

Other names DFB CAS RN [35367-38-5] Development codes DU 112307; PH 60-40; PDD 60-40-I (all Duphar); TH 6040 (T. H. Agriculture & Nutrition Co., Inc.) Official codes OMS 1804; ENT 29 054

PHYSICAL CHEMISTRY Diflubenzuron

Composition Tech. grade diflubenzuron is ³95% pure. Mol. wt. 310.7 M.f. C₁₄H₉ClF₂N₂O₂ Form Colourless crystals; (tech., off-white to yellow crystals). M.p. 228 °C; (tech., 210-230 ºC, decomp.) V.p. 1.2 ´ 10^-4 mPa (25 ºC) (gas saturation method) K_OW logP = 3.89 S.g./density 1.56 Solubility In water 0.08 mg/l (pH 7, 25 ºC). In n-hexane 0.063, toluene 0.29, dichloromethane 1.8, methanol 1.1 (all in g/l, 20 °C). Stability Light-sensitive when in solution, but stable to sunlight as a solid. <0.5% decomposition after 1 d storage at 100 ºC; <0.5% after 7 d at 50 ºC. In aqueous solution (20 ºC), stable at pH 5 and 7 (DT₅₀ >150 d), at pH 9 DT₅₀ 42 d.

COMMERCIALISATION Diflubenzuron

History Insecticide reported by J. J. van Daalen et al. (Naturwissenschaften, 1972, 59, 312) and reviewed by A. C. Grosscurt (Pestic. Sci., 1978, 9, 373) and W. Maas et al. (Chem. Pflanzenschutz-Schädlingsbekämpfungsmittel, 1980, 6, 423). Introduced in 1975 by Philips-Duphar B.V. (now Uniroyal Chemical, part of CK Witco Corp.). Patents GB 1324293; US 3748356; US 3989842 Manufacturers Sundat; Uniroyal

USES Diflubenzuron

Uses For control of a wide range of leaf-eating insects in forestry, woody ornamentals and fruit. Controls certain major pests in cotton, soya beans, citrus, tea, vegetables and mushrooms. Also controls larvae of flies, mosquitoes, grasshoppers and migratory locusts. Used as an ectoparasiticide on sheep for control of lice, fleas and blowfly larvae. Due to its selectivity and rapid degradation in soil and water, diflubenzuron has no or only a slight effect on the natural enemies of various harmful insect species. These properties make it suitable for inclusion in integrated control programmes. Diflubenzuron is effective at 25-75 g/ha against most leaf-feeding insects in forestry; in concentrations of 0.01-0.015% a.i. against codling moth, leaf miners and other leaf-eating insects in top fruit; in concentrations of 0.0075-0.0125% a.i. against citrus rust mite in citrus; and at a dosage of 50-150 g/ha against a number of pests in cotton (cotton boll weevil, armyworms, leafworms), soya beans (soya bean looper complex) and maize (armyworms). Also for control of larvae of mushroom flies in mushroom casing (1 g/m²⁾; mosquito larvae (25-100 g/ha); fly larvae in animal housings (0.5-1 g/m² surface); and locusts and grasshoppers (60-67.5 g/ha). Formulation types GR; HN; OF; SC; UL; WG; WP. Compatibility Incompatible with strongly alkaline products. Selected tradenames: 'Dimilin' (Uniroyal); 'Hilmilin' (Hindustan); 'Kitinex' (Cequisa)

MAMMALIAN TOXICOLOGY Diflubenzuron

Reviews CAG; FAO/WHO 92, 94 (see part 2 of Bibliography). Oral Acute oral LD₅₀ for rats and mice >4640 mg/kg. Skin and eye Acute percutaneous LD₅₀ for rabbits >2000, rats >10 000 mg/kg. Not a skin irritant; slight eye irritant (rabbits). Not a skin sensitiser (guinea-pigs). Inhalation LC₅₀ for rats >2.88 mg/l. NOEL (2 y) for rats 40 mg/kg diet. No teratogenic, mutagenic, or oncogenic effect was observed. ADI (JMPR) 0.02 mg/kg b.w. [2001]; 0.02 (JECFA evaluation) [1994]. Other Acute i.p. LD₅₀ for mice >2150 mg/kg. Toxicity class WHO (a.i.) III (Table 5); EPA (formulation) III

ECOTOXICOLOGY Diflubenzuron

Birds Dietary LC₅₀ (8 d) for bobwhite quail and mallard ducks >4640 mg/kg diet. Fish LC₅₀ (96 h) for zebra fish (Brachydanio rerio) >0.2, rainbow trout >0.2 mg/l. Daphnia LC₅₀ (48 h) 7.1 mg/l. Algae LC₅₀ for Selenastrum capricornutum >0.3 mg/l. Other aquatic spp. LC₅₀ for molluscs >200 mg/l. Bees Not hazardous to bees and predatory insects; LD₅₀ (oral and contact) >100 mg/bee. Worms NOEC for Eisenia foetida 780 mg/kg substrate.

ENVIRONMENTAL FATE Diflubenzuron

EHC 184 (WHO, 1996). Animals In rats, following oral administration, elimination is partly as the unchanged parent compound in the faeces, partly as hydroxylated metabolites (for c. 80%) and as 4-chlorophenylurea plus 2,6-difluorobenzoic acid (for c. 20%). The intestinal absorption is strongly related to the dosage administered - the higher the dosage, the more (relatively) is excreted unchanged in the faeces. See A. Verloop & C. D. Ferrell, ACS Symp. Series, 1977, No. 37, 237. Plants Non-systemic. Not metabolised on plants (idem, ibid.). Soil/Environment Diflubenzuron is strongly absorbed by soil/humic acid complex and is virtually immobile in soil. Rapidly degraded in soil, with a half-life of <7 days. The principal degradation products are 4-chlorophenylurea and 2,6-difluorobenzoic acid (idem, ibid.).

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