Insecticide, acaricide

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 ºC  V.p. 0.25 mPa (20 ºC)  KOW logP = 6.37 (23? ºC, distilled water)  S.g./density 1.2 (20 ºC)  Solubility In water 0.012 mg/l (24 ºC). In acetone 460, ethanol 57, hexane 10, benzene 110, xylene 390, cyclohexane 320, n-octanol 63 (all in g/l, 20 ºC).  Stability Stable at 50 ºC for 90 d; unstable to light. Stable to hydrolysis for 30 d in the dark (pH 5, 7 and 9, 25 °C). 

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