Physical and Chemical Properties Composition A mixture containing ≥80% avermectin B1a (i) and ≤20% avermectin B1b (ii).
Mol. wt. 873.1 (avermectin B1a); 859.1 (avermectin B1b)
M.f. C48H72O14 (avermectin B1a); C47H70O14 (avermectin B1b)
Form Colourless to pale yellow crystals.
M.p. 161.8-169.4 °C (decomp.)
S.g./density 1.18 (22 °C)
Solubility In water 1.21 mg/l (25 °C). In toluene 23, acetone 72, methanol 13, octanol 83, ethyl acetate 160, dichloromethane 470, hexane 0.11 (all in g/l, 25 °C).
Stability Stable to hydrolysis in aqueous solutions at pH 5, 7, and 9 (25 °C). Sensitive to stronger acid and base. UV irradiation causes conversion first to the 8,9-Z- isomer, then to unidentified decomposition products.
Applications of Abamectin Insecticide
Biochemistry: Acts by stimulating the release of γ-aminobutyric acid, an inhibitory neurotransmitter, thus finally activating chloride channels.
Mode of action: Insecticide, acaricide and nematicide with contact and stomach action. Has limited plant systemic activity, but exhibits translaminar movement.
Uses: Control of motile stages of mites, leaf miners, suckers, Colorado beetles, etc. on ornamentals, cotton, citrus fruit, pome fruit, nut crops, vegetables, potatoes, and other crops. Application rates are 5.6 to 28 g/ha for mite control, 11 to 22 g/ha for control of leaf miners. Also used for control of nematodes by seed treatment.
Phytotoxicity: May be phytotoxic to pome fruit when mixed with captan.