Cotton Cotton Beet Nightingale

Scientific name Laphygma exigua Hubner Synonyms Spodoptera exigua Hubner Lepidoptera, Noctuidae. Alias ​​corn leafworm, cabbage brown night moth, Spodoptera exigua. Distributed in most parts of the country.

Hosts cotton, beets, corn, hemp, tobacco, onions, green beans, soybeans, sweet potatoes, cabbage, cauliflower, cabbage, radish, lettuce, tomatoes, green peppers, eggplants, potatoes, cucumbers, zucchini, cowpeas, legumes, fennel, carrots, There are more than 170 kinds of vegetables such as celery, spinach, leeks, and other vegetables.

The newly hatched larvae infested the growing points and young buds, and then damaged the heads, leaves, buds, flowers, and bells, resulting in headless seedlings or leaves that were netted. When the big heads were born, all the heads were killed and the petioles and branches remained. Light stalk seedlings. A larvae has about 20 buds, flowers, and bells. The larvae feed on cotton leaves and pods into holes, and the serious leaf area is more than 20%. Larvae older than 3 years old can also bred the bells, causing bad bells or falling bells. In recent years, the damage of grain, cotton and vegetable fields in Henan, Hebei, Shandong, Anhui and other places has increased. The damage is becoming increasingly severe, generally reducing production by 20% to 30%, and severely up to 50%.

Morphological characteristics Adult body length 8-10mm, wingspan 19-25mm. Gray-brown, black spots on the head and chest. The forewings are gray-brown, with double lines on the anterior segment of the baseline; the internal lines are black and wavy; the sword pattern is a black strip; the ring pattern is yellowish and black; the renal pattern is pink, the central brown, and black; The horizontal line is black and wavy; the horizontal line is black and black, zigzag, and the lines between the front and rear are white; the white lines are white. , Zigzag, black spots on both sides, there is a large black spot on the outside at M1; the edge line is a black spot, and the inside of each point is lined with white. The hind wings are white, and the veins and edges are dark brown. Ovoid globose, white, mass produced in the foliage or the back of the leaves, 8-100 grains ranging from 1 to 3 layers, covered with female fluff off the white fluff, so can not directly see the eggs. The mature larvae are about 22mm in length. Body color varies widely, from green, dark green, yellow-brown, brown to black-brown, with or without a topline, and colors vary. The most obvious feature is that the abdomen valve has a clear yellow-white longitudinal band, sometimes pink, and the end of this band reaches the end of the abdomen and does not bend to the hip foot. Foot). There is a clear white point behind each throttle. Such larvae are often confused with cabbage caterpillars and cabbage larvae in the field. The carcass is about 10mm long, yellow-brown. The chest valve is significantly protruding. There are two bristles on the hip spine and two very short bristles on the ventral base.

Living habits Shandong, Jiangsu, and Shaanxi Guanzhong regions, 4-5 generations a year, 5 generations in Beijing, 5-6 generations in Hubei, 6-7 generations in Jiangxi, Jiangsu, Nanjing, Henan Xinxiang, Shandong, in the earth During the winter, the phoenixes in Nanchang, Jiangxi Province and Hunan, dominate the wintering season, and a few unfamiliar larvae live in weeds or earth seams, and they feed slightly during winter. In the subtropics and tropical regions, it can grow and reproduce all year round. There is no obvious overwintering phenomenon in Guangzhou, and it is harmed all year round. The adult lurks in the grass and subterranean seams during the day and hides at night. The most suitable temperature is 20-23°C and relative humidity is 50-75. %. Phototaxis. Adults lay eggs 3-5 days, each female can produce l00-600 tablets. The egg period is 2-6 days. Larvae were 5 instars (a few 6 instars). Before the 3rd age, the group was harmed, but the food intake was small. After the 4th age, the food intake increased greatly, and it stayed in the night and there was a false death. When the larvae are too large, the larvae can kill each other. The larval development period is 11 to 39 days. Old mature larvae into the soil, spit silk room building maggots, crickets development period of 7-11 days. The starting temperature for overwintering development is 10°C, and the effective development temperature is 220 days. Beet nightingale is an intermittently occurring pest that varies widely in different years. During the year, the damage in July-August in northern China is heavier. Cotton in Henan Province has two generations in cotton fields, from the end of July to the middle of August, and the second generation from late August to late September. In early August, the first generation larvae died.

Prevention methods (1) Autumn tillage or winter tillage can eliminate some overwintering earthworms. (2) Use black light to trap adult insects. During the period of adult generation, the willows were used to attract moths, eliminate adults, and reduce the amount of eggs laid in the cotton fields. (3) Remove weeds in spring from March to April to eliminate the first instar larvae on the weeds. (4) Manual collection of eggs and capture of larvae. (5) Biological control promotes the spraying of more than 100 billion spores of acaricidal or bacteriophage seedling powder per gram, 500 to 700 times the water 500. (6) To control the spraying of 10% cypermethrin EC 1500 times or 40% acephate EC or 90% crystal trichlorfon 1000 times and 5% SYP EC 3000 to 4000 times before the 3rd instar. , 20% Diflubenzuron No. 1 Glue Suspension 500 - 10oo times liquid, 44% Speed ​​Kai EC 1000 - 1500 times, 20% cypermethrin EC or 2.5% Baodi EC 2000 times, 50% Xin Phosphorus EC 1500 times. In addition, you can also use 20% flutter insect net, 40% cyanocyanine EC, 20% methomyl EC and so on. Pay attention to the spray on the tip and the bud and the back of the blade. (7) Advocate the application of sex pheromone preparation method of Spodoptera exigua: When preparing 100 attractants, first dissolve 0.4g of antioxidant 2,6-Di-test-butyl-4-methylphenol (BHT) in 0.3ml of ether. After complete dissolution, add 10 oulZ9, E12-14 : Ac and 10u1 Z9, E12- 14 : OH, add a little diethyl ether to make the volume 0.5 ml, and finally add 0.5 ml corn oil to make the total volume 1 ml. When dispensing, each plastic tube is filled with 10u1 mixture and sealed at both ends. In this way, each lure contained an average of 1 ml Z9, E12-14: Ac and 0.1 ml z9, E12-14: OH. Place 100 per 667m2, excellent control effect.