Avermectin is a microbial fermentation product called Streptomyces avermanii or Streptomyces griseus. Since there are no live microorganisms in them, they are not counted as pesticides of microbial origin. It contains a variety of insecticidal ingredients, of which B1a is the most medicinal and uses it to calculate the effective content of the medicament.
Appearance is light yellow to white crystalline powder, tasteless. m.p.155 ～ 157 ℃, vapor pressure 2 × 10 ^ -7Pa, relative density 1.16 (21 ℃). Solubility at 21 °C: toluene 350g / L, acetone 100g / L, isopropanol 70g / L, chloroform 25g / L, ethanol 20g / L, methanol 19.5g / L, cyclohexane 6g / L, kerosene 0.5g / L, water 10μg / L. The distribution coefficient is 9.9 × 10 ^ 3. It is stable under normal conditions and will not hydrolyze at pH 5-9.
Avermectin mode of action
Avermectin has gastrotoxic and contact killing effects on mites and insects and cannot kill eggs. The mechanism of action is different from general insecticides in that it interferes with neurophysiological activities and stimulates the release of γ-aminobutyric acid, which has an inhibitory effect on the nerve conduction of arthropods. Adults of mites, nymphs and insect larvae appear paralyzed after contact with avermectin, inactive, do not eat, and die after 2 to 4 days. Because it does not cause rapid dehydration of insects, the lethal effect of avermectin is relatively slow.
Studies have shown that the production of Avermectin is related to the following factors: ① strains. Strain selection can not only improve the fermentation units produced by microorganisms, but also change the ratio of each component, thereby increasing the content of the required components. The ratio of B and A in the product can be changed; the morphology of the species should be selected for fermentation with full mycelia (PAMcCann uses medium dextrin 0.4%, meat extract 1%, yeast 0.4%, agar 2%, pH = 7.0). ②C / N ratio. Has a great impact on yield and composition. ③ Defoamer. Polyethylene glycol is a good defoamer, it can not only improve the fermentation unit, but also inhibit the production of an orange waxy substance during fermentation. ④ Stir. It has a great influence on the fermentation effect. Since the mycelium is more sensitive to the impeller shear, the use of hydrofoil wheel stirring device can improve oxygen supply and increase production. ⑤ Inorganic salt. Various other inorganic salts have no beneficial effect on fermentation.
1. To prevent Plutella xylostella and Plutella xylostella, use 1000-1500 times 2% avermectin EC + 1000 times 1% avermectin in the young larvae stage, which can effectively control its damage. The effect is still 90-95%, and the control effect against Pieris can reach more than 95%.
2. To control pests such as Lepidoptera spp., Leaf miner, leaf miner, Liriomyza sativae and vegetable whitefly, etc., use 3000-5000 times 1.8% avermectin EC in the peak period of egg hatching and larval occurrence Double high chlorine spray, the prevention effect is still more than 90% 7-10 days after the drug.
3. To control beet armyworm, use 1,000 times 1.8% avermectin emulsifiable concentrate, the prevention effect is still more than 90% after 7-10 days.
4. To control leaf mites, gall mites, tea mites and various resistant aphids of fruit trees, vegetables, food and other crops, use 4000-6000 times 1.8% avermectin emulsifiable concentrate spray.
5. To prevent and cure vegetable root-knot nematode disease, use 500 ml per mu, the prevention effect reaches 80-90%.
Avermectin cream is a stable homogeneous liquid with low toxicity. Because of its high efficacy and easy application, it has a repelling effect on nematodes, insects and mites, and is a more stable antibiotic insecticide. It is favored by the majority of pesticide manufacturers and farmers.
Because avermectin cream is of low toxicity, it must be stored and transported strictly in accordance with the regulations during storage and transportation. It cannot be stored in a humid place or in the sun, nor can it be mixed with food, seeds and beverages; neither skin nor eyes Direct contact; do not inhale by mouth or nose.
Avermectin side effects
Acute toxicity: No irritation to skin, slight irritation to eyes. It is highly toxic to aquatic organisms and bees and low to birds.
Chronic toxicity: Dogs were fed avermectin at doses of 0.25 mg / (kg · d) and 1.0 mg / (kg · d) for 1 year, and no cumulative toxicity was found. NAOEL is 0.25 mg / (kg · d).
Carcinogenicity: Within the test dose range, avermectin has no teratogenic, carcinogenic and mutagenic effects on animals.
(1) Respiratory tract inhalation: The solvent composition of abamectin emulsifiable concentrate contains aromatic hydrocarbons such as benzene and xylene. When a certain dose is absorbed, central nervous symptoms such as headache, dizziness, movement disorders, muscle tremors, drowsiness, salivation, Chest tightness, shortness of breath, weakness in limbs, unstable walking, etc.
(2) Skin contact: Avermectin is not easily absorbed through the skin and has no irritation effect on the skin. Such as prolonged contact time or frequent exposure to avermectin, occasionally cause skin allergy symptoms, manifested as itchy skin.
(3) Mistake into the eye: It has an irritating effect on the eyes, and experiments have shown that avermectin can cause irreversible damage to the cornea.
(4) Ingestion of the digestive tract: Poisoning by avermectin at low doses is not significant, but at high doses, the drug can have an inhibitory effect on the central nervous system through the blood-brain barrier. Clinically, pupil dilation, anxiety, irritability, Drowsiness, mental depression, excitement, convulsions, muscle tremors, ataxia, may be accompanied by nausea, vomiting, abdominal pain, bloating and other gastrointestinal symptoms. Severe poisoning is extremely rare, mainly manifested as coma and hypotension, and even respiratory depression, which can be caused by frequent convulsions and suffocation or ventricular fibrillation.
Since avermectin has become a commonly used pesticide, the avermectin test is an indispensable part.
The Avermectin Rapid Test kit provided by BALLYA can effectively detect avermectin residues in agricultural products. It is not only simple to operate, but also has short detection time and high accuracy.