Molluscicide, insecticide, acaricide, bird repellent

carbamate

NOMENCLATURE

Common name methiocarb (BSI, Canada, New Zealand, Republic of South Africa, Turkey, ESA, E-ISO); methiocarbe ((m) F-ISO); mercaptodimethur (alternative name, E-ISO, (m) F-ISO, France, Germany); no name (Eire, USA)

IUPAC name 4-methylthio-3,5-xylyl methylcarbamate 

Chemical Abstracts name 3,5-dimethyl-4-(methylthio)phenyl methylcarbamate 

CAS RN [2032-65-7]  EEC no. 217-991-2  Development codes Bayer 37 344; H 321 (Bayer)  Official codes OMS 93; ENT 25 726 

PHYSICAL CHEMISTRY

Mol. wt. 225.3  M.f. C11H15NO2S  Form Colourless crystals, with a phenol-like odour.  M.p. 119 ºC  V.p. 0.015 mPa (20 ºC); 0.036 mPa (25 ºC)  KOW logP = 3.08 (20 °C)  Henry 1.2 ´ 10-4 Pa m3 mol-1 (20 °C)  S.g./density 1.236 (20 ºC)  Solubility In water 27 mg/l (20 ºC). In dichloromethane >200, isopropanol 53, toluene 33, hexane 1.3 (all in g/l, 20 ºC).  Stability Unstable in highly alkaline media. Hydrolysis DT50 (22 ºC) >1 y (pH 4), <35 d (pH 7), 6 h (pH 9). Photodegradation contributes to the overall elimination of methiocarb from the environment; DT50 6-16 d. 

COMMERCIALISATION

History Insecticide reported by G. Unterstenhöfer (Pflanzenschutz-Nachr. (Engl. Ed.), 1962, 15, 181). Introduced by Bayer AG.  Patents FR 1275658; DE 1162352  Manufacturers Bayer

APPLICATIONS

Biochemistry Cholinesterase inhibitor.  Mode of action Molluscicide with neurotoxic action. Non-systemic insecticide and acaricide with contact and stomach action.  Uses Control of slugs and snails in a wide range of agricultural situations. Broad-range control of Lepidoptera, Coleoptera, Diptera, Thysanoptera and Homoptera (including soil insects), and spider mites in pome fruit, stone fruit, citrus fruit, strawberries, hops, potatoes, beet, maize, oilseed rape, vegetables, and ornamentals. Used as seed treatment for control of frit flies on maize, flea beetles on oilseed rape, and leaf miners on beet; and also acts as a bird repellent.  Phytotoxicity May lead to fruit thinning on apple trees, if applied earlier than four weeks after petal fall.  Formulation types DP; GB; RB; SC; WP; Seed treatment.  Compatibility Incompatible with alkaline materials.  Selected tradenames: 'Draza' (Bayer); 'Mesurol' (Bayer)

OTHER TRADENAMES

'Decoy' (Bayer); 'Exit' (Bayer); 'Karan' (Bayer); 'Lupus' (Bayer); 'Rivet' (Bayer)

ANALYSIS

Product analysis by hplc (CIPAC Handbook, 1988, D, 130; AOAC Methods, 1995, 984.10). Residues determined by rplc (ibid., 985.23) or by glc (M. C. Bowman & M. Beroza, J. Assoc. Off. Anal. Chem., 1969, 52, 1054; Anal. Methods Residues Pestic., 1988, Part I, M2, M13). Methods for the determination of residues are available from Bayer. For methods in drinking water, see AOAC Methods, 1995, 991.06. 

MAMMALIAN TOXICOLOGY

Reviews FAO/WHO 83, 85 (see part 2 of the Bibliography).  Oral Acute oral LD50 for male and female rats c. 20, mice 52-58, guinea pigs c. 40, dogs 25 mg/kg.  Skin and eye Acute percutaneous LD50 for male and female rats >5000 mg/kg. Non-irritating to skin and eyes (rabbits).  Inhalation LC50 (4 h) for rats >0.3 mg/l air (aerosol); c. 0.5 mg/l (dust).  NOEL In 2 feeding trials, NOEL for rats and mice 67, dogs 5 mg/kg diet.  ADI (JMPR) 0.02 mg/kg b.w. [1998].  Toxicity class WHO (a.i.) II; EPA (formulation) I  EC hazard T; R25| N; R50, R53 

ECOTOXICOLOGY

Birds Acute oral LD50 for male mallard ducks 7.1-9.4, Japanese quail 5-10 mg/kg. LC50 (7 d) for bobwhite quail: no signs of toxicity as birds were repelled by 'Mesurol'.  Fish LC50 (96 h) for bluegill sunfish 0.754, rainbow trout 0.436-4.7, golden orfe 3.8 mg/l.  Daphnia LC50 (48 h) 0.019 mg/l.  Algae ErC50 for Scenedesmus subspicatus 1.15 mg/l.  Bees Not toxic to bees (depending on mode of application).  Worms LC50 for Eisenia foetida >200 mg/kg dry soil. 

ENVIRONMENTAL FATE