Harm and Control of Spodoptera exigua in Jiangtian Field

Spodoptera exigua (Hubner) belongs to the genus Lepidoptera, Noctuidae, Spodoptera, and is a worldwide distributed polyphagous pest. In general, before the 1980s, the worm was an occasional pest in China and was only listed as a subject of concurrent treatment. Since the mid-to-late 1980s, the worm was gradually raised to some crops, especially important pests of various vegetables. The worm larvae have a wide range of feeding, strong resistance, and extremely difficult to control. In recent years, Spodoptera exigua has been commonly found in ginger growing areas in China, and it is becoming more and more serious. It not only greatly affects the yield of ginger, but also causes a decrease in quality, causing serious losses to the production of ginger in China.

1, feeding and harm

Spodoptera exigua larvae are the most harmful to ginger. Its larvae are generally divided into 5 instars, and 1-2 instar larvae cluster on the dorsal ovum to spit and feed on the leaves. Dispersion hazards after 3rd year of age, increased food intake after 4th instar, and 4-5 years of age damage the gluttony. The older larvae lurked in the plant's roots, soil seams, or grasses during the day and moved to the plants for feeding hazards before and after the evening, until the next morning. The larvae mainly eat the leaves of the ginger (host plants) and eat the leaves into empty or lacking agents. When the larvae are severe, the entire leaves are bitten and eaten, leaving only the veins and petioles, leading to plant death, lack of seedlings and ridges, affecting the crops. Yield and quality.

2. Control methods

2.1 Agricultural control in general is: to strengthen agricultural management and promote rational distribution. In late autumn and early winter, the soil is plowed and the debris in the soil is removed in time to eliminate part of the overwintering pupae, which can reduce the amount of occurrence in the coming year. In combination with farming operations in the summer, cultivators or irrigation are performed to remove egg masses or larvae. In addition, it has been observed in recent years that the egg masses of Spodoptera exigua have also been distributed on field weeds. Therefore, the weeds in the field and surrounding areas should be promptly removed.

2.2 The trapping and killing of Spodoptera exigua adults has the characteristics of phototaxis, chemotaxis, etc., and likes to act on some flowering honey source crops, feeding, spawning, according to which can be trapped and killed. At present, the most frequently used and effective measures are the following: light trapping, sex trapping, planting and trapping plants, and poplar trapping. Light trapping usually uses 20W black light.

2.3 Biological control Biological control has unique advantages over other control measures. It can effectively control the damage of Spodoptera exigua, it can also reduce the use of chemical pesticides, reduce environmental pollution, and protect natural enemies. Promote a virtuous cycle of farmland ecosystems. There are two specific situations: (1) Comprehensive use of various measures to protect, multiply, and use natural enemies. The beet armyworm has a large number of natural enemies and is rich in resources. According to statistics, there are more than 100 types of parasitic and predatory natural enemies that have been identified. According to statistics, the death rate of Spodoptera exigua caused by parasitic, predatory natural enemies and pathogenic bacteria can reach more than 99% in areas not treated with insecticides. Therefore, we should make full use of reasonable cultivation techniques and scientific farming practices, vigorously promote balanced formula fertilization, minimize the use of various chemical pesticides, thereby reducing the harm to natural enemies and enhancing the biological control effect of Spodoptera exigua. (2) Biological pesticide control. Biological pesticides do not pollute the environment and have long-lasting effects, and they have no toxic effects on natural enemies. It would be better to use chemical pesticides in a reasonable way. At present, there are Bt preparations, Bt insecticidal variants, Bt and Su Yunjin rodin mixed agents.

2.4 Chemical prevention With the increase of people’s health awareness and the development of green food, the use of chemical pesticides is continuously decreasing. However, in practical production practices, some rational use of high-efficiency, low-toxicity, and new-type pesticides against Spodoptera exigua Still play a very good role.

2.4.1 Selection of Pharmaceutic Drugs Sucralose, Anti-Tai Bao, Gai-Meng San, Diflubenzuron No. 4 and Nongmeng Te have good control effects on Spodoptera exigua. In addition, Spodoptera exigua is responsible for organic phosphorus and organic chlorine. Chrysanthemum pesticides show strong resistance, so when using these types of pesticides, it is necessary to pay attention to reasonable and comprehensive application.

2.4.2 The application technology of Spodoptera exigua has the characteristics of latent dorsal and netting hazards. Therefore, in the spraying control must ensure that the plant should be fully sprayed up and down, all around; the application time is also very important, preferably in the early morning and late evening, and must be in the egg to control the larva before the third instar, Because, Spodoptera exigua is generally dormant and harmful, and the older larvae are extremely resistant.

Tests show that the following mixes of several agents have good control effects:

(1) Mix 1,000 times An Lvbao and 500 times 8010 powder;

(2) The first to mix with the enemy to kill;

(3) Mixing 80% of dichlorvos 1000-1500 times with 20% of kungfu inulin 3000 times;

(4) Mix 50% phoxim EC with 1000 times 90% crystal trichlorfon 1500 times;

(5) Mixing 80% of dichlorvos EC 1000-1500 times with Bt biocides 300-500 times; (6) 25% dimehypobic agent 500 times and 25% Diflubenzuron 3 1500 times.

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