Acaricide
pyrazole (acaricide)


NOMENCLATURE
Common name fenpyroximate (BSI, draft E-ISO)
IUPAC name tert-butyl (E)-a-(1,3-dimethyl-5-phenoxypyrazol-4-ylmethyleneamino-oxy)-p-toluate 
Chemical Abstracts name 1,1-dimethylethyl (E)-4-[[[[(1,3-dimethyl-5-phenoxy-1H-pyrazol-4-yl)methylene]amino]oxy]methyl]benzoate 
CAS RN [134098-61-6]; [111812-58-9] unspecified stereochemistry  Development codes NNI-850 (Nihon Nohyaku); HOE 555-02A (Hoechst)

PHYSICAL CHEMISTRY
Composition Tech. is 97.0%.  Mol. wt. 421.5  M.f. C₂₄H₂₇N₃O₄  Form White, crystalline powder.  M.p. 101.1-102.4 ºC  V.p. 0.0075 mPa (25 ºC)  K_OW logP = 5.01 (20 ºC)  S.g./density 1.25 g/cm³ (20 °C)  Solubility In water 1.46 ´ 10^-2 mg/l (20 ºC). In methanol 15, acetone 150, dichloromethane 1307, chloroform 1197, tetrahydrofuran 737 (all in g/l, 25 ºC).  Stability Stable in acid and alkali.

APPLICATIONS
Biochemistry Inhibitor of mitochondrial electron transport at complex I.  Mode of action Quick knockdown activity against larvae, nymphs and adults, mainly by contact and ingestion. Also some moulting inhibitory activity on nymphs.  Uses Control of important phytophagous mites. Effective against Tetranychidae (spider mites), Tarsonemidae, Tenuipalpidae (false spider mites) and Eriophyidae in citrus, apple, pear, peach, grapes, etc.  Phytotoxicity Not phytotoxic to top fruit, citrus, tea, vegetables and ornamentals.  Formulation types SC.

ANALYSIS
Product analysis by hplc; residues in soil by glc, in water by hplc, in plants by glc/hplc.

MAMMALIAN TOXICOLOGY
Reviews FAO/WHO 74, 76 (see part 2 of the Bibliography). See also J. Pestic. Sci., 17, S261-267 (1992).  Oral Acute oral LD₅₀ for male rats 480, female rats 245 mg/kg.  Skin and eye Acute percutaneous LD₅₀ for male and female rats >2000 mg/kg. Non-irritating to skin; slightly irritating to eyes (rabbits).  Inhalation LC₅₀ (4 h) for male rats 0.33, female rats 0.36 mg/l.  NOEL for male rats 0.97, female rats 1.21 mg/kg b.w.  ADI (JMPR) 0.01 mg/kg b.w. [1995].  Other Not carcinogenic, teratogenic or mutagenic in long-term studies.  Toxicity class WHO (a.i.) II

ECOTOXICOLOGY
Birds LD₅₀ for bobwhite quail and mallard ducks >2000 mg tech./kg. Dietary LD₅₀ (8 d) for bobwhite quail and mallard ducks >5000 ppm.  Fish LC₅₀ (48 h) for carp 0.006 mg/l.  Daphnia LC₅₀ (3 h) 0.085 mg/l.  Bees No adverse effect on honeybees at 250 ppm (5 ´ recommended dose).  Other beneficial spp. Relatively non-toxic to predacious mites. Little adverse effect at 25-50 ppm on Chrysopa nipponensis, Harmonia axyridis, Ephedrus japonicus, Misumenops tricuspidatus, Lycosa pseudoannulata, Orius sp., Scolothrips sp.

ENVIRONMENTAL FATE
Soil/Environment DT₅₀ 26.3-49.7 d (J. Pestic. Sci., 18, 67-75 (1993)).