Spodoptera exigua, mustard cabbage is very common, under what conditions are it easy to appear?

In the heat of summer, such conditions can easily appear. Spodoptera exigua, also known as Spodoptera exigua and Spodoptera exigua, belongs to the Lepidoptera and Noctuidae family. Damage statusSpodoptera exigua is widely distributed and occurs in all parts of China, especially in Northeast China, Xinjiang, Inner Mongolia, North China, Northwest China, East China, Central China and Sichuan.

Spodoptera exigua is a polyphagous pest with a wide range of hosts, affecting more than 100 crops in about 45 families. Among them, the more serious crops are asparagus, cabbage, cabbage, radish, mustard greens, tobacco, spinach, carrots, sugar beets and beans, and can also harm eggplant, melons and food crops. In North China, it mainly harms autumn cruciferous vegetables, and in the northeast and northwest regions and other sugar beet producing areas, the damage is also very serious.

Spodoptera exigua mainly damages leaves as larvae. The larvae are first hatched, that is, they gather on the back of the leaves to feed on the mesophyll, and the residual epidermis is in the form of a gauze network. At 2-3 years of age, the leaves are bitten into holes or notches.

After the 4th instar, the damage is dispersed, and the food can be eaten day and night before the 5th instar, and the 6th instar is only nocturnal and lurks in the soil around the rhizosphere during the day. Only the veins and stems of the leaves were left behind. Larger larvae can also bury into the leaf bulb and excrete a large amount of feces, causing rot in the leaf bulb, which seriously affects the quality and yield of vegetables.

When it is severe, it is common to move to another after eating one piece of land, causing large-scale devastating losses.

Habits: 2 generations occurred in Heilongjiang in 1 year, 3 generations in Liaoning in 1 year, and 3-4 generations in Sichuan in 1 year. Pupae are used to overwinter in the soil in all places. In the area where the second generation occurs in the first year, the overwintering pupae emerge in May and the fourth generation in March.

The second generation is in mid-July, and the third generation is in late August. There are two obvious damage periods in vegetables, the first time is from early June to early July, that is, the first generation of larvae damage cabbage, spinach and other vegetables. The second is from early September to early October, and it is the third generation of larvae, which mainly damages cabbage.

The second generation of insects occurs in the hot summer, and the occurrence is very light due to the discomfort of temperature and humidity.

The adults of the overwintering generation need to suck nectar to supplement nutrients in order to prolong their life and increase their egg production. The presence or absence of nectar plants during the adult generation period can affect the occurrence of the next generation. In the spring, the occurrence of insect infestation is more serious in areas where cruciferous vegetables are left to grow or fruit trees bloom.

Spodoptera exigua usually appears in the hot summer months and mainly damages the leaves as a larvae.

The temperature is high, it is easy to appear in dry weather, this bug likes hot weather, and this bug is very fond of eating vegetable leaves.

1.Autumn droughts are frequent, which is conducive to the occurrence of pests. High temperature and drought are conducive to the outbreak of Spodoptera exigua, because the drought in July and August is not conducive to the reproduction of Beauveria bassiana, an important natural enemy of Spodoptera exigua, so the larval survival rate is high and the harm is serious.

2.The use of drugs is illegal. First, the medication is not timely.

The vast number of peasants often do not see the insect and lose the period of insect control. The appropriate period for the control of Spodoptera exigua larvae is the peak period of egg incubation, when the larvae are small, the amount of food is small, and the group is harmful, and there is no eye-catching harm. The prevention and control can not exceed the 3rd instar, and after the 3rd instar, the food damage will be dispersed, the resistance will be enhanced, and the control effect will be very poor.

Second, the amount of medicine is large and the amount of water is small, so it is difficult to spray evenly. Third, there is a lack of effective organization and inconsistent insect control actions. 3.

Increased insect resistance. Long-term irrational drug use has led to a significant increase in the resistance of Spodoptera exigua.

Spodoptera exigua mainly injure the leaves of crops, the larvae of the first hatch are gathered together, on the back of the leaves, do not move during the day, and live at night to eat the leaves, and the remaining epidermis is lurking under the leaves, cabbage and the soil around the surface or roots during the day, and come out at night to form gluttony. It is very harmful to crops.

This organism has a strong influence on the leaves of plants, they feed on mesophyll, and they also excrete in large quantities, causing leaf bulbs to rot, affecting the yield and quality of vegetables.

With the development of society, more and more people choose to grow crops at home. The crops grown by yourself are not only clean and hygienic, but also nutritious. Mustard greens are one of the most popular vegetables, but Spodoptera exigua is a very common pest of mustard greens.

So when you find that the mustard greens you grow are infested by Spodoptera exigua, how should you prevent and control it? <>

First, biological control, if the mustard is in the harvest season, people can carry out autumn or winter ploughing to eliminate pupae. This method is a very effective way to eradicate pests at the root. It is also possible to trap with a black light and then kill the infestation.

Finally, there is the release of the natural predator of the Spodoptera exigua, the red-eyed bee, and when the Spodoptera armyworm encounters the red-eyed wasp, then its number is greatly reduced. The above methods are biological control, which not only ensures the quality of mustard, but also ensures the quantity of mustard. <>

2. Chemical controlWhen they find that they are planting camellia with insect pests, the first method that people think of must be spraying pesticides. Because this method is not only fast and effective, but also can kill insect infestations quickly. Although the use of pesticides may also have a good impact on the crops they grow, it will not have much impact on the crops if people spray them in moderation.

Because pesticides are inherently toxic, people should be mindful of how much they spray when using them. If it is sprayed excessively, it will have an inhibiting effect on the growth of mustard greens. If you really don't know how to spray, you can ask your neighbors for advice, and sometimes asking someone else for help may save you a lot of detours.

3. Physical controlPhysical control is the most easy-to-understand method, and it is also the most direct method to eliminate pests. When you are planting mustard, you can ask a friend or family member to observe the growth of mustard after a period of time to determine whether it is infested by pests. If you find that you are infested by pests, you should take immediate measures to manually kill the pests.

Pesticides should be sprayed in a timely manner, and the right medicine should be prescribed, and water and fertilizer management should also be done, and weeds should be removed regularly, and pest pests should be removed.

Relevant pesticides should be sprayed in advance, and at the same time, the infection of various pests and diseases should be prevented, and attention should be paid to ventilation and management methods.

If you want to control Spodoptera exigua, you should first sprinkle pesticides and pesticides on the ground when planting mustard greens, so that you can avoid this creature from getting close to mustard greens.

It can be controlled with pesticides. Some pesticides can kill these moths.

In the spring, when many fruits and vegetables are planted during this season, this problem is easy to occur.

It is almost in autumn, because it is easy to cause problems with this mustard in autumn, and it needs to be controlled more in this season.

Spring is frequent, because it rains a lot at this time, and the climate is very humid, which will allow the virus to enter the mustard greens.

The characteristics are different: the larvae of Spodoptera exigua are black, with coarse hairs on the whole, about 2 mm in length, the adults are grayish-brown, with giant claws at the end of the tibiae of the forefeet, the larvae of Spodoptera exigua are green, with yellowish-white longitudinal stripes on both sides, the adults are grayish-brown, and the outer edge of the forewings consists of a row of small black triangular spots.

The occurrence rules are different: Spodoptera exigua will emerge when the temperature rises to 15-16, and 3-4 generations can occur in 1 year in the northern region, and 5-6 generations can occur in 1 year in the Yangtze River basin, and the more generations occur in the south, the more generations will occur.

First, the characteristics are different

1. Spodoptera exigua: the larvae are slightly dark, all have coarse hairs, the body length is about 2 mm, and the second instar larvae are all green; The adult body and wings are grayish-brown, the compound eyes are blackish-purple, and there are giant claws at the end of the tibia of the forefoot.

2. Spodoptera exigua: the larvae are green or dark green, with yellowish-white longitudinal stripes on both sides, and 1 white markings above the back of the valve; The body color and forewings of adults are grayish-brown, and the outer edge of the forewings is composed of a row of small black triangular spots, and the kidney-shaped and ring-shaped lines are yellowish-brown.

Second, the law of occurrence is different

1. Spodoptera exigua: The pupa overwinters 10 cm below the surface, and the pupa will emerge when the temperature rises to 15-16, and 3-4 generations can occur in 1 year in the northern region. The occurrence time in Liaoning is from mid-May to mid-June, and the occurrence time in Shandong is from early May to early June.

2. Spodoptera exigua: Pupae overwintering in the soil, 5-6 generations can occur in 1 year in the Yangtze River Basin, 7 generations can occur in a few years, the closer to the south, the more generations occur each year, and 10-11 generations can occur in 1 year in Guangdong. There is no overwintering phenomenon in South China, and it can be harmful and multiplying all year round.

Third, the prevention and control methods are different

1. Spodoptera exigua: before the larvae are 3 years old, spray 8000-10000 times of 10% Uranus EC, or 4000-5000 times of 21% killer EC, or 3000 times of 50% pine moth-killing EC, spray 1 time every 10-15 days, and spray 2-3 times in a row.

2. Spodoptera exigua: After the larvae enter the peak hatching period, spray 1000-2000 times of 25% chlorpyramide emulsifiable concentrate at 8 o'clock in the morning or 6 o'clock in the evening, or 1000 times of 5% cypermethrin emulsifiable concentrate 500 times of 5% fipronil dispersible liquid, or 1000 times of cyfluthrin emulsifiable concentrate and 500 times of 5% fipronide emulsifiable concentrate.

<> Spodoptera exigua is an omnivorous pest belonging to the phylum Arthropods, Insecta, Lepidoptera, and Noctuidae. Spodoptera exigua is mainly a shed to damage the leaf chain of crops with larvae, the larvae at the beginning of hatching will gather together on the back of the leaf to eat, and in severe cases, they can often eat up the mesophyll, leaving only the leaf veins and petioles, and then eat one place and then become a closed group and migrate to another place for damage.

Morphological characteristics of Spodoptera exigua: Adult: body length 20 mm, wingspan 45 mm, tan color, forewings with distinct kidney-shaped spots (white inside the spots) and annular spots, and a small black spot on the outer edge of the hindwings.

Eggs: pale yellow, hemispherical, but all have a brown papillae, longitudinal ridges and transverse grids on the surface.

Larvae: Mature larvae have brown heads, body lengths of 50 mm, pale green ventral surface of the carcass, yellow-green or tan on the back, and inverted figure-eight lines on the back of each segment of the brown type.

Pupa: about 20 mm long, tan.

Spodoptera exigua pests: Spodoptera exigua eats miscellaneous and can harm more than 120 species of plants in 45 families, such as cabbage, cabbage, rape, radish and spinach of the cruciferous family, green peppers, tomatoes, eggplants, potatoes and other crops of the Solanaceae family.

But it is mainly cabbage and cabbage. The first hatched larvae gather the back of the leaves of vegetables to feed on the mesophyll, after the 3rd instar, the leaves are eaten into notches or holes, and after the 4th instar, they are scattered as a pest, feeding day and night, the 6th instar larvae are latent in the rhizosphere soil during the day, and the unearthed at night is a pest, and the older larvae can burrow into the leaf balls such as cabbage and cabbage, which seriously affects the quality and yield of vegetables.