In agricultural production, it is inevitable that there will be "invasion" of pests. There is a type of insect that is particularly annoying. They are very small and hidden. When they first occur, it is not easy to find, but they reproduce very quickly. They often "explode" in a few days, causing serious harm to our crops. One of them is thrips. Today we will take stock of what drugs can be used to prevent and control thrips?
1. About thrips
Thrips are pests of the order Thysanoptera and the superfamily Thripoidea. There are more than 7,400 species of thrips recorded worldwide, and more than 400 species of thrips recorded in my country. Common ones include western flower thrips, melon thrips, onion thrips, rice thrips, etc.
Thrips are small, with a body length of only 1-2 mm. They occur all year round, mainly in the open field in spring, summer and autumn, and mainly in greenhouses in winter. They have a rasp-sucking mouthparts, which use adults and nymphs to rasp the plant epidermis and suck the juice inside the plant. They can harm the leaves, growth points, flowers, young fruits and other parts of crops, and can also spread diseases such as viral diseases.
2. Thrips control agents
There are many agents for controlling thrips. Currently, there are more than 30 active ingredients registered for thrips control, which can be mainly divided into the following categories:
(1) Nicotinoids: such as imidacloprid, acetamiprid, thiamethoxam, clothianidin, dinotefuran, etc.
(2) Biological insecticides: such as emamectin benzoate, matrine, veratridine, Metarhizium anisopliae, Beauveria bassiana, spinetoram, etc.
(3) Organophosphorus: such as fenthion, malathion, etc.
(4) Carbamates: such as carbaryl, carbosulfan, etc.
3. Common thrips control agents
(1) Emamectin benzoate
Emamectin benzoate is a derivative of avermectin. It is produced by chemical synthesis based on avermectin. It is a semi-synthetic antibiotic insecticide. Its mechanism of action is to interfere with the neurotransmission system of pests. It has stomach poison and contact killing effects. After 3-4 days, the peak period of pest death will appear.
(2) Thiamethoxam
Thiamethoxam is a second-generation nicotinoid insecticide. It mainly acts on the central nervous system of pests, blocks the normal conduction of the nervous system, paralyzes pests and causes death. It also has contact killing, stomach poison and systemic activity. It has the characteristics of high efficiency, low toxicity and broad insecticide spectrum.
Thiamethoxam can be widely used in rice, corn, wheat, potato, peanut, tobacco and fruit trees. It can be used not only for spraying, but also for seed treatment, soil treatment, root irrigation, root dipping, etc. It can effectively control aphids, planthoppers, whiteflies and other piercing-sucking mouthparts pests.
(3) Chlorfenapyr
Chlorfenapyr is a new type of pyrrole insecticide with contact and stomach poisoning effects. It can be used on vegetables, fruit trees, and field crops to control a variety of pests such as Lepidoptera and Homoptera, such as cabbage worms, beet armyworms, cabbage borers, leafminers, thrips, and other vegetable pests. It is especially effective against adult Lepidoptera pests.
Chlorfenapyr has good permeability and systemic conductivity. It can kill pests within 1 hour after application and reaches a peak of dead insects within 24 hours. It has a high control effect on resistant pests, especially for pests and mites resistant to organophosphorus, carbamate, pyrethroids, etc., and has a good effect.
(4) Dinotefuran
Dinotefuran belongs to the third generation of neonicotinoid insecticides. Its mechanism of action is the same as that of traditional nicotinoid insecticides. It is also a nicotinic acetylcholine receptor agonist. It reaches the point of action in the form of free base and affects the synapses of the insect central nervous system by interacting with the acetylcholine receptors of the insect postneural membrane, causing pest paralysis and ultimately leading to the death of the pest.
Dinotefuran can be widely used in the prevention and control of piercing-sucking and chewing mouthparts pests on plants, such as aphids, rice planthoppers, whiteflies, whiteflies, thrips, etc. In addition to its direct insecticidal effect, dinotefuran also has the effect of affecting the physiological activities of pests such as feeding, mating, egg laying, and flying.
(5) Spirotetramat
Spirotetramat belongs to the new tetronic acid derivative insecticide and is a lipid biosynthesis inhibitor. Its mechanism of action is to inhibit the synthesis of fat by inhibiting the biosynthesis process of fat in the pest body, blocking the normal energy metabolism of the pest and ultimately leading to death.
Spirotetramat is mainly stomach poison and supplemented by contact poison. It can be used to control various pests with piercing-sucking mouthparts, such as aphids, thrips, whiteflies, mealybugs, scale insects, and blind bugs. It is effective against adults, larvae, nymphs, and eggs, especially against piercing-sucking mouthparts pests in the larval stage.
(6) Clothianidin
Clothianidin is a broad-spectrum neonicotinoid insecticide with contact, stomach poison, and systemic activity. Like other nicotinoid insecticides, it acts on the nicotinic acetylcholine receptors of insect postsynapses. It is mainly used on rice, vegetables, fruit trees, and other crops to control aphids, leafhoppers, thrips, planthoppers, blind bugs, cabbage worms, and other Hemiptera, Coleoptera, Diptera, and some Lepidoptera pests. It can also be used to control garlic maggots, leek maggots, root maggots, cutworms, wireworms, grubs, and other underground pests.
(7) Spinetoram
Spinetoram is a biological insecticide produced by fermentation of the actinomycete Saccharopolyspora spinosa. It is low-toxic, low-residue, and safe for humans and non-target animals. Spinetoram is an analog of spinosad and has a similar mechanism of action, but it has a broader spectrum than spinosad and is mainly used to control lepidopteran pests and thysanoptera pests. Currently, the registered control targets in my country are mainly beet armyworm, armyworm, diamondback moth, bean pod borer, American leafminer, thrips, aphids, etc.
Spinetoram is also one of the most popular insecticides for controlling thrips.
(8) Tolfenpyrad
Tolfenpyrad belongs to the pyrazoline amide class of insecticides. It works by blocking the electron transport system complex in the mitochondrial metabolic system. It has a contact effect, can kill eggs and inhibit egg laying, has a broad insecticide spectrum, is highly effective, has low toxicity, and has a good rapid effect. Its effective period can reach about 10 days. It is mainly used to control Lepidoptera larvae such as diamondback moth and Thysanoptera pests such as thrips.
In addition to the above-mentioned agents, agents that are often used to control thrips include imidacloprid, pymetrozine, acetamiprid, thiacloprid, cypermethrin, bromofenac, cyanamide, etc.; there are also some agents that have not been registered for the control of thrips, but in actual production, they are often used to control thrips, such as nitenpyrad, pyriproxyfen, diafenthiuron, sulfoxaflor, and flonicamid.
Precautions
(1) Due to differences in regional environment and drug use levels, the drug resistance of thrips in different regions is also different. Many drugs are easy to use in some areas, but may have serious resistance problems in other areas. When controlling pests, it is necessary to combine the local drug use characteristics or drug use habits.
(2) When a drug is confirmed to be easy to use, do not use it repeatedly for a long time. Try to use it alternately or mix it with other drugs with different mechanisms of action to prevent pests from developing resistance quickly.
