Insecticide, acaricide, ixodicide

pyrethroid

NOMENCLATURE

Common name fenvalerate (BSI, E-ISO, (m) F-ISO, ESA)

IUPAC name (RS)-a-cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutyrate 

Chemical Abstracts name cyano(3-phenoxyphenyl)methyl 4-chloro-a-(1-methylethyl)benzeneacetate 

CAS RN [51630-58-1] unstated stereochemistry  Development codes S-5602 (Sumitomo); WL 43 775 (Shell)  Official codes OMS 2000 

PHYSICAL CHEMISTRY

Composition Tech. grade fenvalerate is 92.1% pure.  Mol. wt. 419.9  M.f. C25H22ClNO3  Form Tech. fenvalerate is a viscous yellow or brown liquid, sometimes partly crystalline at room temperature.  M.p. 39.5-53.7 °C (pure)  B.p. Decomposes on distillation.  V.p. 1.92 ´ 10-2 mPa (20 ºC)  KOW logP = 5.01 (23 ºC)  S.g./density 1.175 (25 ºC)  Solubility In water <10 mg/l (25 ºC). In n-hexane 53, xylene ³200, methanol 84 (all in g/l, 20 ºC).  Stability Stable to heat and moisture. Relatively stable in acidic media, but rapidly hydrolysed in alkaline media.  F.p. 230 °C 

COMMERCIALISATION

History Insecticide reported by N. Ohno et al. (Agric. Biol. Chem., 1974, 38, 881) and results of field trials by M. D. Mowlam et al. (Proc. Br. Crop Prot. Conf. - Pests Dis., 1977, 2, 649). Introduced by Sumitomo Chemical Co., Ltd and, in some countries, by Shell International Chemical Co. (who no longer manufacture or market it).  Patents GB 1439615; US 4062968 both to Sumitomo  Manufacturers Agrochem; Aimco; Ankur; Bharat; Dhanuka; Ficom; Gujarat; JIE; Krishi Rasayan; New Chemi; Parry; Rallis; RPG; Sanachem; Shenzhen Jiangshan; Sumitomo; United Phosphorus

APPLICATIONS

Mode of action Non-systemic insecticide and acaricide with contact and stomach action.  Uses Control of a wide range of pests, including those resistant to organochlorine, organophosphorus, and carbamate insecticides. Uses include control of chewing, sucking, and boring insects (particularly Lepidoptera, Diptera, Orthoptera, Hemiptera, and Coleoptera) in fruit, vines, olives, hops, nuts, vegetables, cucurbits, cotton, oilseed rape, sunflowers, alfalfa, cereals, maize, sorghum, potatoes, beet, peanuts, soya beans, tobacco, sugar cane, ornamentals, forestry, and on non-crop land. Used for control of flying and crawling insects in public health situations and in animal houses. Also used as an animal ectoparasiticide.  Formulation types EC; UL; SC; WP.  Compatibility Incompatible with alkaline materials.  Selected tradenames: 'Sumicidin' (Sumitomo); 'Arfen' (Ramcides); 'Cekufenvalerato' (Cequisa); 'Dufen' (Dhanuka); 'Fenkill' (United Phosphorus); 'Fenny' (Nagarjuna Agrichem); 'Fenval' (RPG); 'Kayvalerate' (Krishi Rasayan); 'Newfen' (Gharda); 'Sanvalerate' (Sanachem); 'Shasicidin' (Sanonda); 'Starfen' (Shaw Wallace); 'Sumitox' (Aimco)

OTHER TRADENAMES

'Bhasma' (Biostadt); 'Fencur' (BEC); 'Fenero' (Sabero); 'Fenirate' (Agrochem); 'Krifen' (Krishi Rasayan); 'Parryfen' (Parry); 'Qingwujuzhi' (Shenzhen Jiangshan); 'Shamiethrin' (Zhong-Xi); 'Stalker' (Indofil); 'Tribute' (Aventis); 'Triumphcard' (Dhanuka); 'Valour' (Crop Health); 'Vapcocidin' (Vapco); 'Vifenva' (Vipesco) mixtures: 'Fenikill' (+ fenitrothion) (Vapco); 'Miejingthrin' (+ propargite) (Zhong-Xi); 'Pre Ling' (+ phoxim) (Zhong-Xi); 'Vegehon' (+ dimethoate) (Agros); 'Vifensu' (+ fenitrothion) (Vipesco) Discontinued names: 'Belmark' * (Cyanamid); 'Pydrin' * (Du Pont)

ANALYSIS

Product analysis of pyrethroids reviewed by E. Papadopoulou-Mourkidou in Comp. Analyt. Profiles. By hplc (idem, ibid.; E. Papadopoulou-Mourkidou, Anal. Methods Pestic. Plant Growth Regul., 1988, 16, 31; 1984, 13, 121) or by glc (CIPAC Handbook, 1988, D, 100; ibid., 1995, G, 68-70). Residues determined by glc with ECD (ibid.; A. Ambrus et al., J. Assoc. Off. Anal. Chem., 1981, 64, 733; Man. Pestic. Residue Anal., 1987, I, 6, S19; Anal. Methods Residues Pestic., 1988, Part I, M11). Details available from Sumitomo Chemical Co. 

MAMMALIAN TOXICOLOGY

Reviews FAO/WHO 47 (see part 2 of the Bibliography). See also A. J. Gray & D. M. Soderlund, Chapt. 5 in "Insecticides".  IARC ref. 53  class 3  Oral Acute oral LD50 for rats 451 mg/kg.  Skin and eye Acute percutaneous LD50 for rabbits 1000-3200, rats >5000 mg/kg. Slightly irritating to skin and eyes (rabbits).  Inhalation LC50 for rats >101 mg/m3.  NOEL (2 y) for rats 250 mg/kg diet.  ADI (JMPR) 0.02 mg/kg b.w. [1986].  Toxicity class WHO (a.i.) II; EPA (formulation) II 

ECOTOXICOLOGY

Birds Acute oral LD50 for domestic fowl >1600, mallard ducks 9932 mg/kg. Dietary LC50 for quail >10 000, mallard ducks 5500 mg/kg.  Fish LC50 (96 h) for rainbow trout 0.0036 mg/l.  Bees Toxic to bees. Contact LD50 0.23 mg/bee. 

ENVIRONMENTAL FATE

EHC 95 (WHO, 1990).  EHC 95 cites rapid degradation and decomposition, reduced toxicity of its degradation products, and absence of leaching in soil. Although laboratory tests show high toxicity for fish and bees, these effects are markedly reduced under field conditions because of adsorption to sediments, and the compound's strong repellent effect. The report concludes that risks to the environment are unlikely when it is applied as recommended.  Animals In mammals, following oral administration, fenvalerate is rapidly metabolised. Up to 96% is excreted in the faeces within 6-14 days. For a study of the metabolism of fenvalerate in the laying hen, see J. Agric. Food Chem., 1989, 37, 190.  Plants In plants, fenvalerate is split into two parts by cleavage of the ether group, followed by further hydroxylation in the 2- and 4- positions of the phenoxy ring, and hydrolysis of the nitrile group to amide and carboxyl groups. The majority of the acids and phenols thus formed are converted into glucosides.  Soil/Environment In aqueous media, the ester bond is hydrolysed. In light, decarboxylation occurs, with recombination of the cleaved moieties (R. L. Holmstead et al., J. Agric. Food Chem., 1977, 25, 56-58). DT50 in soil c. 75-80 d.