Morphological characteristics, occurrence rules and key prevention and control techniques of Shanhua Li Tianniu
1 Morphological characteristics
1.1 Adult insect The body is oblong-shaped, the front end of the body expands into a circle, head-like, the head is flexible, the back is slightly flattened, there is a pair of long antennae, the antennae are born on the protrusions of the forehead, the length is more than 1/2 of the body; the claws are usually single-toothed, a few are attached to the teeth; the mouthparts are suitable for chewing; the body color is diverse, mostly tan, sometimes variegated and bright, or similar to the trunk color, with hidden and protective effects; the mid-chest dorsal plate often has a pronouncer, which can rub the foreth chest and the mid-chest to make a "squeaking" sound.
1.2 The shape of the egg varies according to the species, generally oblong-ovate, sometimes broader cylindrical, oval or ovate, fusiform, flattened; the color is white, and the length is generally 0.5 ~ 5.0 mm [[Jishan Huayao]].
1.3 Larvae Are pale yellow or white in color, thick and fat, long barrel-shaped, a few slender, yellow or brown heads, tightened into the anterior thorax, tiny antennae, only 2 or 3 segments, large jaws are developed, there are stripes on both sides and in the center of the dorsal plate of the forebreast, and the thorax and feet are developed according to different species, and some are microscopic and even degenerate.
1.4 Pupae Naked pupae, with distinct body segments, similar proportions to adults, antennae curled around the body, pupae of milky white or yellow color, usually located in the pupal chamber.
2 Harmful symptoms
Tianniu can start from the larval to the adult stage, with the larval stage being the most serious pest. The larvae first moth under the bark of the tree until the second year, and when the insect grows up, it moths into the xylem. After the mountain plum is damaged by the tianniu, moth holes and scars will appear on the surface of the trunk and branches of the fruit tree, and as the larvae continue to grow, the borer hole gradually deepens until it reaches the center of the branch, and the outside of the borer hole is piled with reddish-brown sawdust or sawdust worm dung and wood chips, and sometimes the sap flowing out. After the Celestial Bull harms the mountain plum fruit tree, it will cause hollowness in the tree, hinder the circulation of sap, and weaken the tree. This will lead to a decline in the yield of Shanhua plum, the fruit becomes smaller, and the nutritional value decreases, which makes the economic value of Shanhua plum suffer greater damage.
3 Occurrence
3.1 Life Habits Adult insects generally appear in May and July of each year, and males predate females. Spawning begins in July and August, and there is a certain need for luminosity and temperature when spawning, and the temperature is preferable to around 21 °C in areas with a large luminosity [5]. The adult worm first bites a scar on the trunk and branches of the mountain plum tree, and then lays the eggs into it. After about 2 weeks, the eggs can hatch into larvae, the larvae are first active under the bark when they are born, and obtain nutrients by mothting the fruit tree, and when the larvae go deep into the fruit tree, they will build a wide pit in the fruit tree as a pupal chamber, and the two ends are closed by wood chips, where the pupae are pupated, and the pupal stage is 10 to 30 d. After feathering, adults will crawl out of the feathered hole, feed and copulate during the day, lay eggs in the evening, and generally live in 10 to 30 days. Tianniu mainly feeds on the tender bark, young branches, leaves, branches, sap and fruit of Shanhua plum fruit tree, Wang Jian et al.[8] Through the test of the feeding habitability of pine brown Tianniu on the harvested healthy and disease-free Masson pine, it was found that the number of larvae bred by each female pine was 3.0 to 28.0 heads, with an average of 12.3 heads, and the rate of subcutaneous tissue being eaten and destroyed was 3.0% to 85.0%, with an average of 25.6%. These data show that the tianniu supplements its own nutrition and reproduces offspring by eating forest trees, which will cause serious damage to forest planting.
3.2 Generations The occurrence of Tianniu generations varies according to the region, there are 1 or 2 generations completed in one year, and there are also 2 ~ 5 a completed generations, and it has been reported that Zhejiang, Jiangxi and other provinces and regions Tianniu 2a occurs in a generation or 3 a generation. The same species varies greatly according to different regions, and generally occurs once a year in Guangdong, with a harmful period of up to 6 months. Xu Jielian et al. found that the pupae stage in Guangdong is generally 4-5 months, the adult stage is 5-7 months, the egg stage is 7-8 months, and the larval stage is August-April of the following year. The larval stage can reach 8 months and the infestation period can be up to 5 to 6 months. Celestial bulls are generally young
Worms or adults feathered in autumn overwinter, and a small number of pupae overwinter.
3.3 Spawning methods There are many kinds of Tianniu, and the spawning methods are also diverse. However, almost all celestial cows produce secretions before and after spawning to build egg chambers and thus protect eggs. In general, there are two main ways for Tianniu to lay eggs, one is to have the habit of laying eggs in slots, the female worm first bites the bark with her upper jaw before giving birth, and then inserts it with the spawning tube, one grain per hole, and also produces multiple grains. After laying the eggs, the female secretes a transparent gelatinous mucus that covers the laying hole, which is a good way to protect the eggs from external environmental influences. Another way to lay eggs is not to bite the hole, but to lay eggs directly with the spawning tubes in the gaps in the bark. In a few cases, it also occurs on the smooth parts of the branches. Tianniu, who uses this spawning method, generally excretes secretions twice before and after spawning, and the color is generally grass green, which may be related to the concealment of eggs.
3.4 Harmful situations
3.4.1 Investigation of occurrences
3.4.1.1 Time and place of investigation From 2013 to 2016, an investigation was conducted on the pest infestation of Shanhua Litian cattle in Niumuling Mountain, Taowei Town, Jianghua County.
3.4.1.2 Respondents The age of the tree is 7 ~ 20 a, and the variety is Shanhua plum.
3.4.1.3 Investigation method The entire orchard is sampled according to the method of interlaced interlaced plants. The species and number of tianniu on each mountain plum fruit tree were investigated separately, and the number of cattle in the winter was investigated, and the fruit tree was judged whether there was a tianniu parasitism by observing the situation of the tianniu insect road, slot and egg, and finally calculated the infestation rate and hatching rate of the tianniu.
4 Analysis of the causes of disasters
4.1 Tianniu larvae life is hidden Due to the living habits of Tianniu, the Tianniu larvae have a high degree of concealment, and its larval stage is very long, so that the Shanhua Li planters do not know the Tianniu larvae very well, nor can they immediately distinguish when they see the larval feces, and take correct control measures.
4.2 Few professionals The number of professionals engaged in the agricultural and animal husbandry industry is rare, and mainly scientific research institutes, university scholars, etc., due to their own energy and working environment restrictions, although they have mastered advanced technology and cutting-edge knowledge, they still cannot teach experience and technology to front-line fruit farmers in time, there is a lag. When insect pests occur, fruit growers cannot distinguish due to lack of relevant professional knowledge, and professionals with relevant knowledge cannot accurately judge the situation because they cannot grasp the pest situation in time, so they cannot prevent and control insect pests in time.
4.3 Aging and Scattered Knowledge At present, most of the knowledge of Tianniu mastered by fruit growers comes from science
Technical books and personal experience are relatively old and scattered, and they cannot form a systematic knowledge system.
As a result, it is difficult to respond in a timely manner to new situations and not to adapt to the current work
need. Therefore, when insect infestations occur, growers who lack a systematic knowledge system cannot
Making sound judgments leads to further expansion of pests and irreparable results
Economic losses.
5 Key prevention and control technologies
5.1 Biological control method Tianniu pheromones include sex pheromones, host pheromones,
Xenopheromones, avoidance pheromones, and interferon spawning hormones due to the activity of the Celestial Bull
The characteristics of concealment and dispersion of hazards, so the use of conventional prevention and control methods has a larger
Limitations, and the use of pheromones for prevention and control is highly specific, less polluting and more
Disadvantages such as less susceptibility to drug resistance [13]. For adult insects, it does not supplement nutrients and has a long distance
Tenniu, a detached pheromone, can concentrate on releasing sex pheromones to lure tengus. Right
In adult worms in the reproductive stage, egg-laying pheromones can be used to lure the day
cattle. For adult Tianniu that need to supplement nutrition, feeding lure information can be used
It has always seduced the Celestial Bull. In order to improve the efficiency of pheromone attraction, compounds may also be used
Pheromones. There are reports that the attractant and the Tianniu pathogenic microorganism are combined to make
Use energy to improve the prevention and control effect.
5.2 Agricultural Control Methods Through field surveys and indoor captivity experiments, adult Tianniu has been found to prefer neem trees and silver sugar maples [14,15]. Therefore, in the actual planting process, these two trees can be used as bait trees to lure the celestial cattle, and neem trees can have a luring effect on the celestial cattle at a distance of 200 m. In general, bait trees can be planted next to ventilated forest paths, and there should be a certain distance from the mountain plum. In addition, the Celestial Bull not only has a preference for certain trees, but also has a clear dislike for another tree. The study found that Tianniu has a strong aversion to the tzketone produced by camphor trees, and this natural substance produced by camphor trees has the effect of avoiding, smoking and touching adult Tianniu, so it can also be planted at a certain distance in the Mountain Plum planting forest for insect repellent. Combining the two, planting camphor trees in the Shanhua Plum Forest to repel insects, and planting neem trees or silver sugar maples at a certain distance outside the forest to trap the Tianniu, can achieve a better control effect. In this way, it is simple and economical, does not cause biological pollution, and has a remarkable effect.
5.3 Physical Control Method For shanhua li tianniu insect infestation, the most direct control method is to directly capture adult insects, kill larvae, and remove egg blocks. May to July every year is the peak of the emergence of adult insects, according to the living habits of adult insects, can be artificially captured. For the larvae, when the trunk of the tree is inspected during the day and the larval feces are found, the larvae can be killed in time with tools such as fine wires, or the cotton soaked with dichlorvos can be selected to plug the moth channel, or the dichlorvos diluted with water can be directly injected into the moth channel with a syringe, and finally the insect mouth is sealed with mud. For those eggs with low spawning sites, the egg laying scars can be artificially tapped to kill the eggs and small larvae, but the impact should not be too strong to prevent damage to the fruit tree; lime, sulfur powder, and water can also be mixed into a stone sulfur compound in the ratio of 10 : 1 : 40 to brush the white trunk. The advantages of the direct prevention and control method are that the effect is fast and the time is short, but it requires more manpower.
5.4 Chemical control method The traditional control method is not very ideal for the effect of Shanhua Li Tianniu insect infestation, so the new Tianniu poison signature can be used. Poison stick is a new type of insect road fumigation made of a mixture of metal phosphides and oxidants and other chemicals, when used, the poison stick is inserted into fresh worm holes, and the mortality rate of pests can reach more than 90% per hole. This method is simple to operate and easy to use, but the price of the poison tag is high and it is not easy to save, so it is suitable for short-term temporary use.
Shanhua Plum, also known as Sanhua Li, belongs to the Rosaceae family, is a species of Plum genus in China, because it was first planted in Sanhua Town, Wengyuan County, Guangdong Province, and is known as "King of Lizhong" and "Lingnan Top Ten Fruits". Because of its juicy and delicious, aromatic, light and crisp meat, moderate sweet and sour and rich taste, containing 11.9% carbohydrates, 0.6% ~ 2.0% fruit acid, 0.7% protein, rich in vitamin E content, with high nutritional value, loved by customers, with high economic value.
