Pyridaben 20%WP

NOMENCLATURE
Common name pyridaben (BSI, draft E-ISO)
IUPAC name 2-tert-butyl-5-(4-tert-butylbenzylthio)-4-chloropyridazin-3(2H)-one
Chemical Abstracts name 4-chloro-2-(1,1-dimethylethyl)-5-[[[4-(1,1-dimethylethyl)phenyl]methyl]thio]-3(2H)-pyridazinone
CAS RN [96489-71-3] Development codes NC-129; NCI-129 (both Nissan); BAS-300I (BASF)

PHYSICAL CHEMISTRY
Mol. wt. 364.9 M.f. C19H25ClN2OS Form Colourless crystals. M.p. 111-112 篊 V.p. 0.25 mPa (20 篊) KOW logP = 6.37 (23? 篊, distilled water) S.g./density 1.2 (20 篊) Solubility In water 0.012 mg/l (24 篊). In acetone 460, ethanol 57, hexane 10, benzene 110, xylene 390, cyclohexane 320, n-octanol 63 (all in g/l, 20 篊). Stability Stable at 50 篊 for 90 d; unstable to light. Stable to hydrolysis for 30 d in the dark (pH 5, 7 and 9, 25 癈).

COMMERCIALISATION
History Insecticide and acaricide reported by K. Hirata et al. (Proc. 1988 Br. Crop Prot. Conf - Pests Dis., 1, 41). Discovered and introduced by Nissan Chemical Industries, Ltd and first marketed in Belgium in 1990. Manufacturers Nissan

APPLICATIONS
Biochemistry Inhibitor of mitochondrial electron transport at complex I Mode of action Non-systemic insecticide and acaricide. Rapid knockdown and long residual activity. Active against all developing stages, especially against the larval and nymph stages. Uses Control of Acari, Aleyrodidae, Aphididae, Cicadellidae and Thysanoptera on field crops, fruit trees, ornamentals and vegetables, at 5-20 g/hl or 100-300 kg/ha. Formulation types EC; SC; WP. Selected tradenames: 'Sanmite' (Nissan)

OTHER TRADENAMES
'Nexter' (Nissan); 'Dinomite' (Vapco); 'Pyramite' (Nissan, BASF); 'Samite' (Sanonda) Discontinued names: 'Poseidon' * (Nissan); 'Starling' * (Nissan, Zeneca)

ANALYSIS
Details from Nissan.

MAMMALIAN TOXICOLOGY
Oral Acute oral LD50 for male rats 1350, female rats 820, male mice 424, female mice 383 mg/kg. Skin and eye Acute percutaneous LD50 for rats and rabbits >2000 mg/kg. Non-irritant to eyes and skin (rabbits). Non-sensitising to skin (guinea pigs). Inhalation LC50 for male rats 0.66, female rats 0.62 mg/l air. NOEL (78 w) for mice 0.81 mg/kg daily; (52 w) for dogs 0.5 mg/kg daily. Other Non-mutagenic in Ames, DNA repair, in vitro chromosomal (Chinese hamster), and mouse micronucleus tests; non-teratogenic in rats and rabbits. Toxicity class WHO (a.i.) III (20 WP); EPA (formulation) I (75 WP)

ECOTOXICOLOGY
Birds Acute oral LD50 for bobwhite quail >2250, mallard ducks >2500 mg/kg. Fish LC50 (96 h) for rainbow trout 1.1-3.1, bluegill sunfish 1.8-3.3 mg/l; (48 h) for carp 8.3 mg/l. Daphnia EC50 (48 h) 0.59 mg/l (nominal concentration). Algae Does not significantly affect the average specific growth rate of Selenastrum capricornutum. Bees LD50 (oral) 0.55 mg/bee. Worms LC50 (14 d) 38 mg/kg soil.

ENVIRONMENTAL FATE
Animals In the rat, goat and hen, an orally administered dose is excreted mainly in the faeces. Metabolism is complex, with at least 30 degradates. Plants After application to citrus and apple, pyridaben degrades gradually photochemically and is not translocated into the pulp. Soil/Environment Readily degrades microbiologically in aerobic soils, DT50 <21 d; further degrades to polar products (including soil-bound residues) and CO2. In natural water, DT50 10 d (25 癈, in dark). DT50 for aqueous photolysis c. 30 min (pH 7). See also Stability.