Rice longitudinal leaf borer (hereinafter referred to as rice longitudinal) is a major common pest on rice, with migratory and explosive nature, and basically occurs in all rice areas in China. According to monitoring, at present, the rice vertical damage in some fields is relatively serious, and it is expected that the overall rice vertical will show a more heavy occurrence trend this year. Rice is a leaf-rolling leaf that eats the flesh of the leaf, resulting in whitening of the leaves and a decrease in photosynthesis and reduced yield. Generally, it can cause losses of about 20%, and serious production can be reduced by more than 50%. There are also many articles on rice sludge on the platform, but there is not much elaboration on its entire generational development process, especially the larval chronology and pests. For pest control, it is generally necessary to carry out the development stage of its young larvae (nymphs) to achieve the best effect, but farmers usually miss the best control period because they are not accurate, resulting in poor control effect after spraying. Today, I will lead you to reveal its development process and harmful symptoms, analyze the factors affecting the effect, how to accurately grasp the prevention and control period and use drugs for scientific prevention and control, and achieve "insect rations to grab food".
Rice longitudinal curl leaf borer adult
Rice in the field is harmful
Rice is a pest of the Lepidoptera borer family, mainly rice. Tillering in rice can be harmful until the filling stage. Rice even in various parts of China in a year occurrence of algebra, of which the north latitude of 30 degrees south of the rice area can overwinter perennial occurrence as a pest, the largest number of generations, dozens of generations per year, and is the source of insects in the northern rice area, the northern rice area generally occurs 1-3 generations. Rice longitudinal is a complete attitude insect, which goes through four stages of development of eggs, larvae, pupae and adult worms in its lifetime (for those that do not go through the pupa development process, they are called incomplete metamorphosis insects), of which only the larval stage is pest. Rice from spawning in the entire developmental generation of adults less than 30 days, more than 40-50 days, the length of time of each generation and its development stages will vary according to environmental conditions, but no matter how many generations it occurs, as long as you understand its development stage, know how to grasp the prevention and control period to scientific prevention and control there is no need to worry.
First, the development process and harmful characteristics of rice throughout life.
Adults: yellow-brown, body length about 1 cm, wings spread about 12-18 mm, the outer edge of the wing has a brown broad edge, there are three black-brown transverse lines on the wings, of which the near outer edge is the longest and the middle is the shortest. Adult life span average 7 days, more than 5-7 days, the longest 12 days, of which feathered adults 1-2 days after the early morning began mating and spawning, mating time of about 1 hour, spawning period of 3-4 days, the average laying of 100 eggs, up to 314 grains, 1-2 days after spawning death. Adult insects like to be dense, good growth, nitrogen fertilizer is more than a field block, hidden in the field or grass during the day, mainly active at night, will fly in case of alarm, but the distance is not far, there is phototropism, the general number of adult insects in the field is large, the occurrence is heavy, and the control period can also be judged according to the number of adult insects in the field (specifically explained later).
Eggs: the eggs are nearly round or oval, flattened, about 1 mm or so, generally a single grain is scattered on the 2-3 leaves of rice pouring, a small number of 2-3 grains are connected together, of which the back of the leaf is the majority, generally poor vision or difficult to find when older. Eggs are milky white after spawning, pale yellow before hatching, and if found to be black, they are invalid eggs parasitized by predators. Eggs generally begin to hatch as larvae about 4 days after they are laid, mainly from 7 to 10 a.m.
Larvae: The larval stage is generally about 16-23 days. Specifically more than the temperature and other related, the general temperature is high and the growth is fast. A larvae can infest 5-10 leaves, of which the 1-3 instar stage is small due to the small size of the insect, the amount of food is small, the damage area is small, and the degree of loss is light. It is generally divided into 5 instars according to the size of the larvae
1st instar: Newly hatched larvae are pale yellowish-green, black-headed, about 1.7 mm long, and generally enter the 2nd stage for about 3 days after hatching. After hatching, the larvae first climb back and forth from the leaf tip along the leaf vein, which is relatively slow, and then crawl into the rice heart leaf or leaf sheath and the old leaf curl leaf bud or thrips to form a leaf roll to feed, resulting in needle-like white dots, which are generally not easy for non-professionals to identify, but at this time the insect is small, and the resistance to low spray control is the best.
2-3 longitudinal eggs on the leaves
Single-grain rice longitudinal eggs
2nd age: yellow-green body, about 3 mm long, head brown, 4 black spots in the middle of the forethia, green esophagus in the body is faintly visible, generally 2-3 days later into the development of the 3rd age stage. After 2 instar, the larvae are more active, the crawling speed becomes faster, and will climb to the tip of the leaf or the middle and upper part of the rice leaf to promote the two sides of the leaf to bond, form a leaf longitudinal roll of the small insect buds, and then eat the leaf flesh inside to form a transparent short white strip, but the general leaf edge adhesion point is less, the bonding length is short, or the leaf is not adhesion, usually called the curl tip or bundle leaf stage, which is also a period when the field is easier to judge the prevention and control, and the prevention and control is usually very good at this time.
3 years old: green body, brown head, body length of about 6 mm, 2 triangular black spots on the anterior chest, obvious markings on the middle and posterior chest, after which the esophagus is clearly visible. Generally the larvae 3 instar stage for about 3 days, the 3-instar larvae spit silk to bind the leaves is strong, the bud leaves are not only tightly bonded, but also relatively long, good closure, the buds become larger and longer, the leaf flesh nibbling area can usually reach a quarter to half of the rolled leaves, at the same time, after the infestation will also be transferred to other leaves to re-roll the leaves for feeding, the transfer time is mostly carried out at 7-8 o'clock in the evening or 4-5 o'clock in the morning when the temperature is not high, and the rainy day can also be transferred, which is why the late field leaf curl is more, and the insect is less. At this time, the general prevention effect will begin to decline, and the general rice will quickly retreat to avoid peeling the curly leaves. At this time, the prevention and control effect is significantly reduced.
Rice longitudinal 1 instar larvae
4 years old: body about 9 mm, green, head dark brown, black brown stripes on the back of the middle and back of the chest, 4 years of stage is generally 3-4 days, after entering the 4th age, the insect buds increase, the area of harm is also significantly increased, usually the leaf flesh nibbling area accounts for more than half of the rolled leaves, causing the leaves to be white, peeling off the curly leaves, the larvae quickly retreat backwards, do not pay attention to it will fall, and the leaves are frequently turned into pests, the resistance is obviously strong, the harm is heavy, and the general farmers spray more during this period, and then there will be frequent spraying after the effect is not good.
5 years old: body length of more than 15 mm, yellow-green to orange-red, head brown, mostly 5-6 days, although the amount of food taken, turning buds into harm frequently, but its action began to be delayed, especially after 1-2 days, not only less activity, but also stop eating for harm, after 5 years of age the strongest resistance, the worst control effect.
Pupae: mostly in the lower leaf or leaf sheath, about 1 cm long, long cylindrical, initially pale yellow, then reddish brown to brown, generally pupate stage 7-9 days, and then feathered into adults to begin to enter the next generation of developmental cycle process.
Rice longitudinal 2nd instar larvae
2-instar rice longitudinal larvae
Second, the main reasons for the poor effect of rice longitudinal control:
Our large number of experimental demonstrations and practical applications show that as long as you grasp the best control time of spraying, rice is actually very good to control, but farmers usually cause problems such as rice not dying after spraying, poor effect, and aggravation of harm because of the following factors.
The appropriate period is not accurate, and the medicine is late. Rice longitudinal control is generally to be in the field just before the discovery of a large number of curly leaves or small insect buds, that is, 2-year-old larvae and their previous control, of which the first-instar stage after hatching to 3 days is the best effect, and the general farmers find that when they are pest medicine, it is basically 3 years old and later, and the effect is certainly not good. In particular, the later the spray, the worse the effect. It is also the main factor affecting the effect,
The amount of medicine is insufficient, and the amount of water is small. The normal dose recommended for pesticide registration is for the 1-2 instar stage of rice, and when the farmer sprays late, the insect age is larger, and the resistance is enhanced, and the effect of using the normal dose is definitely reduced. In addition, rice is hidden in the buds of insects, and the water consumption is small. The rapid spraying speed in the field not only makes it difficult for the agent to effectively contact the insect body, but also after spraying, the low concentration of the agent for leaf distribution and absorption will also directly affect the effect.
3-4 instar larvae
Spraying is uneven, fog droplets are larger, farmers like to use more sprayers, or dragged stretcher sprayers, generally causing more spraying in some areas, less spraying in some areas, coupled with low degree of atomization, fog droplet particles are large, especially the more sprinklers, the worse the atomization performance, so that the amount of liquid distribution on the leaves and the extension time is reduced, and the effect will be significantly reduced.
Increased resistance, high temperature effects. Farmers generally have the use of a drug to control the effect is good, the next time will continue to use, because of the long-term frequent use of a pesticide control, pests will soon develop resistance to it, affecting the effect of control, especially the higher the resistance, the worse the effect, while spraying the temperature is higher, the liquid volatilization is fast, the short residence time will also reduce the effect.
Generations overlap and cure difficulties. Because rice is a pest that continues to migrate from the south, coupled with the pests that migrate into the local breeding in the early stages, the development progress of the field is usually different, and the control effect will also have a certain impact, but as long as the amount of insects in the field is larger, it is more obvious.
3. Scientific prevention and control technology
For rice longitudinal control, in addition to selecting insect-resistant varieties for planting, combining nitrogen, phosphorus and potassium, avoiding partial application of nitrogen fertilizer, excessive density, and appropriate drying of the field, using natural enemies and other ecological control and reduction of harm, the most important thing is to learn to select the right agent, and seize the critical period of prevention and control, and carry out scientific prevention and control.
5-year-old mature rice longitudinal larvae
Field occurrence as a pre-pest: that is, when the field adults are found, the general number of adult insects in the field is not high, usually the field natural enemies can be effectively controlled, once it is found that there are more than 4-5 adult insects per square meter in the field, it will usually lay eggs for more serious harm, generally can be used in time to choose predators or ether oxystrobin and other knockdown strong agents and morning field spraying, so that you can effectively kill adult insects, reduce egg laying as a pest, if you find adult insects in the field, you can also use lamps or sex attractants and other field traps in time to control, It can also be very good to reduce its occurrence. In particular, in areas with many algebraic occurrences of rice, it is better to carry out lamp-trapping or sexual trapping to kill adult insects during the period of rice tillering to fertilization and fruiting, while the algebra occurs in the north with less direct field spraying to kill adult insects.
The initial stage of pest in the field: that is, the incubation period to the 2nd instar larval stage, although the 1st instar larval stage is the best time for control, but the general farmer should not find and grasp, once the field is found to be harmful, it is basically an advanced age stage. Therefore, for the initial judgment and grasp, in addition to finding that there are more than 40 new insect buds per hundred bushes with just curled tip or bundle leaves in the field, or there are more than 50 larvae that need to be sprayed in time, it can also be found in the field after a large number of adult insects are sprayed within 7-10, and it is basically its incubation peak to the 1 instar larval stage, for those who can identify the eggs and their development progress, they can also have more than 150 eggs in the hundred bushes, and most of them are controlled after 1-2 days after yellowing, and the effect of the drug is generally very good as long as the selection of registered rice longitudinal control is very good. For example, Thuringiensis, or avermectin, or methylphenidate, propionate, tetrachlorofenamide or chlorhexamide. Although the use of Bacillus thuringiensis 6000iu/microliter 400-500 ml, or 5% avermectin 10 ml, or 5% methyl vitamin salt 10-20 ml or 30% indicosyl 6-8 grams, etc. is not good after the 3th age of rice, the basic effect of spraying at this time is still very good.
Occurs in the middle of the field, that is, in the 3-4 instar stage, usually the buds are larger, the leaves have a large number of long spots or a large area of white, because the insect body is large and the resistance is strong, it is advisable to choose a compound agent mixed with different types of agents for prevention and control, and the dosage should also be appropriately increased, or the highest recommended dose can be used, such as 10% A dimension can be used per mu. Indate 20 ml, or 40% methyl veronale. Chlorpyrifos 50 ml. or 20% Avi. Indicosyl 20 ml, or 6% Avi. Chlorovenzoyl 40-50 ml or 34% beta-methoxazole 20-24 ml, etc.
When the field occurs in the late stage, that is, the 4-5-year-old larvae, or when it is found that the generation overlap in the field is serious, the large and small insects are all available and the number is large, it is advisable to spray 33% cyanoflate hydrazone 40-50 ml, or 22% cyanidium methylvidate 40-50 ml, or 34% ethyl polymethode 30 ml spray control, usually the effect is better.
Rice longitudinal test spraying
Rice is harmful in the field
A few tips to improve the longitudinal prevention effect of rice: 1. For adult insect control, when spraying, you can spray medicine from the periphery of the field to inward, which can reduce escape and improve the effect. 2. When spraying, the 3-5 cm aqueous layer should be maintained in the field for 5-7 days, and the spraying in the middle and late stages of the field should be sprayed with silicone or synergists such as anrongle or kinesibility, which can reduce the dosage or improve the effectiveness. 3. When spraying, the amount of medicine should be used, generally not less than 30 kg, of which the spray should be sprayed in the evening or before 10 am. 4. To rotate and alternate use of different mechanisms of action, generally a large number of occurrences, serious overlap of generations, or when the field is more harmful, it is advisable to prevent it twice, once every 7 days.
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