ABAMECTIN
IDENTIFICATION
Common name: Abamectin
Other name: Abamectin (BSI, draft E-ISO, ANSI ); abamectine ((f) draft F-ISO)
Chemical abstracts name: 5-O-demethylavermectin A1a (i) mixture with 5-O-demethyl-25-de (1-methylpropyl)-25-(1-methylethyl) avermectin A1a (ii)
Type: Insecticide for Agriculture
CAS RN: [71751-41-2] (abamectin); [65195-55-3](i); [65195-56-4](ii)
M.F.: C48H72O14 (avermectin B1[x|a|x]); C47H70O14 (avermectin B1[x|b|x])
S.F.:
Mol Wt: 873.1 (avermectin B1a); 860.1 (avermectin B1b)
PHYSICAL CHEMISTRY
Form (appearance): A mixture containing > 80% avermectin B1a (i) and < 20% avermectin B1b (ii). Colourless to pale yellow crystals.
M.P.: 161.8-169.4℃(decomp)
V.P.: <3.7×10-3 mPa (25℃)
S.G.: 1.18 (22℃)
Solubility: In water 7-10 μg/l (20℃). In toluene 350, acetone 100, isopropanol 70, chloroform 25, ethanol 20, methanol 19.5, n-butanol 10, cyclohexane 6 (all in g/l, 21℃).
Stability: Stable to hydrolysis in aqueous solutions at pH 5,7, and 9 (25℃). Sensitive to stronger acid and base. U.V. irradiation causes conversion first to the 8,9-Z-isomer, then to unidentified decomposition products
Henry: 2.7×10-3 Pa m3 mol-1(25℃)
KowlogP: 4. 4+/-0.3(pH 7.2, room temperature)
APPLICATION
Formulation types: EC.
Biochemistry: Acts by stimulating the release of γ-aminobutyric acid, an inhibitory neurotransmitter, thus causing paralysis. See M.J.Turner & J.M.Schaeffer in lvermectin and Abamectin, W.C.Cambell ed., Springer-Verlag, New Youk (1989) p.73.
Mode of action: Insecticide and acaricide with contact and stomach action. Has limited plant systemic activity, but exhibits translaminar movement
Uses: Control of motile stages of mites, leaf miners, suchers, Colorado beetles, etc. on ornamentals,cotton,citrus fruit, pome fruit, nut crops, vegetables, potatoes, and oter crops. Application rates are 5.6 to 28 g/ha for mite control, 11 to 22 g/ha for control of leaf miners. Also userd for control og fire ants
Phytotoxicity: May be phytotoxic to pome fruit when mixed with captan
MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for rats 10, mice 13.6 mg/kg (in sesame oil).
Skin and eye: Acute percutaneous LD50 for rabbits >2000 mg/kg. Mild eye irritant; non-irritating to skin (rabbits).
ADI: (JMPR) 0.002 mg/kg b.w. [1997] (for sum of abamectin and 8,9-Z- isomer): 0.001 mg/kg b.w. [1995] (for residues not containing △-8,9 isomer).
/(JMPR) 0.002 mg/kg b.w. [1997] (for sum of abamectin and 8,9-Z- isomer): 0.001 mg/kg b.w. [1995] (for residues not containing △-8,9 isomer).
/Other Non-mutagenic in the Ames test. Other Non-mutagenic in the Ames test.
Toxicity: EPA (formulation) IV
ECOTOXICOLOGY
Birds: Acute oral LD50 for mallard ducks 84.6, bobwhite quail >2000 mg/kg.
Fish: LC50 (96 h) for rainbow trout 3.2, bluegill sunfish 9.6 μg/l.
Daphnia: EC50 (48 h) 0.34 ppb.
Algae: >100 mg/l.
Other aquatic spp. LC50 (96 h) for pink shrimp (Panaeus duorarum) 1.6, blue crab (Callinectes sapidus) 153 ppb.
Worms: LC50 (28 d) for earthworms 28 mg/kg soil. /Bees Toxic to bees.
ENVIRONMENTAL FATE
Plant: Degradation/metabolism in each of three different plants is similar and occurs predominantly by photolysis on the plant surfaces. The definition of the residues is thus expressed as the combined residues of avermectin B1 and its 8,9-Z avermectin B1 photoisomer.
Animals: Rapidly eliminated (80-100% in 96 h), mainly via faeces; urinary excretion was 0.5-1.4%.
Soil/Environment: Binds tightly to soil, with rapid degradation by soil micro-organisms. No bioaccumulation.
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