Spodoptera exigua harms its larvae. Young larvae eat mesophyll, leaving transparent spots on the epidermis. The third instar larvae can eat the leaves into notches, and the whole leaves can be eaten into nets at the fourth and fifth instars. In severe cases, most or all leaves are eaten, leaving only veins and petioles. Seedling damage of beet, radish and Chinese cabbage can cause serious seedling shortage and even destroy seeds. Larvae will also rot the fruits of green peppers and tomatoes, causing the fruits to rot and fall off. Spodoptera exigua is a worldwide intermittent pest, which has a serious occurrence trend in China in recent years. Biological insecticides for controlling Spodoptera exigua mainly include Bacillus thuringiensis, Spodoptera exigua nuclear polyhedrosis virus, Helicoverpa armigera nuclear polyhedrosis virus and emamectin benzoate. Because biological pesticides are slower than chemical pesticides, it is best to control them in advance or at a young age.

(1) Bacillus thuringiensis (Bt) preparation use 15000 IU/mg Bacillus thuringiensis water dispersible granules, the dosage is 25 ~ 50 ml per mu, and water spray. (2) The main formulations in emamectin benzoate are 0.5% EC and 1% EC. The registered dosage of 0.5% EC is 0/.5 ~ 2.25g per hectare/kloc-0, and the converted preparation is 20 ~ 30ml per mu. The registered dosage of 1% EC is 2.25 ~ 4.5g per hectare of active ingredients, and the dosage is 0/5 ~ 30ml per mu. Spray water. (3) The products of Spodoptera exigua nuclear polyhedrosis virus include 2 billion virus particles /ml suspension and 30 billion virus particles /g water dispersible granules. When using 2 billion virus particles /ml suspending agent, 70 ~ 120 ml water should be sprayed per mu. When using 30 billion virus particles/gram water dispersible granule, use 5 grams of water per mu. Attention when using: ① This product should be used in the peak period of Spodoptera exigua spawning; ② Pay attention to uniform spraying; (3) Because the dosage of 30 billion virus particles/gram of water dispersible granule is small, in order to ensure the use effect, it is necessary to dilute the drug twice. Firstly, uniformly mixing the medicine with a small amount of water, and then adding enough water to dilute; ④ Apply pesticide in the evening or cloudy days to avoid direct sunlight; ⑤ Mainly spray new crop parts, leaf backs and other parts that pests like to eat. (4) The product of Helicoverpa armigera nuclear polyhedrosis virus is 654.38+000 billion virus particles/ml suspension, and the preparation is 654.38+000 ~ 654.38+050 ml per mu, which is sprayed with water. Precautions are the same as those of Spodoptera exigua nuclear polyhedrosis virus. (5) The product of Bacillus thuringiensis is 10000 virus particles/microliter. The content of Bacillus thuringiensis is 2000 IU/microliter, and 75 ~ 100 ml of water is sprayed per mu. Precautions are the same as those of Spodoptera exigua nuclear polyhedrosis virus.