Flupyrazofos

Description

Water solubility of flupyrazofos is 0.8 mg/L. Log Kow = 5.24. Flupyrazofos is slowly hydrolyzed in aqueous media; DT₅₀ at pH 4, 7, and 9 are 266, 180, and 121 h, respectively. Vp 3.7 mPa (25 ?C). Flupyrazofos is a nonsystemic insecticide used for the control of caterpillars, especially diamondblack moth, Plutella xylostella, larvae.

The Uses of Flupyrazofos

Flupyrazofos is a new pyrazole organophosporus insecticide, which has a high activity against the diamond-back moth (Plutella xylostella).

The Uses of Flupyrazofos

Flupyrazofos is a new insecticide under development which has shown good activity against caterpillars, especially Plutella xylostella larvae.

Metabolic pathway

The principal route of metabolism of flupyrazofos is by oxidative desulfuration to the oxon which is hydrolysed, principally via base rather than esterase catalysis, to 1-phenyl-3-trifluoromethyl-5-hydroxypyrazole. The physico-chemical parameters of flupyrazofos, including water solubility, hydrolysis rates, vapour pressure and octanol/water partition coefficients, have been reported by Kim et al. (1997).

Metabolism

The principal route of metabolism of flupyrazofos is by oxidative desulfuration to the oxon, followed by hydrolysis to 1- phenyl-3-trifluoromethyl-5-hydroxypyrazole and diethyl hydrogen phosphate. Flupyrazofos is degraded in soil with DT₅₀ of about 14 d.

Degradation

The hydrolytic half-life at pH values 4, 7 and 9 was 266, 180 and 121 hours, respectively (Kim et al., 1997). Flupyrazofos showed good photostability. The photodegradation products which were identified were flupyrazofos oxon (2), 1-phenyl-3-trifluoromethyl-5-hydroxypyrazole (3) and the thiono-thiolo rearranged isomer O,S-diethyl O-(1-phenyl-3- trifluoromethyl)pyrazol-5-yl phosphorothioate (4) (Cho et al., 1993) (Scheme 1).

Toxicity evaluation

Acute oral LD₅₀ for rats is 372–605 mg/kg.