The occurrence of tianniu has brought immeasurable harm to forestry production and greening. Therefore, by analyzing the causes of the formation of Tianniu's harm, starting from the protection and improvement of the ecological environment, and achieving sustainable control as the goal, corresponding prevention and control measures are proposed in order to help tianniu control.
The Celestial Bull is a general term for insects of the Coleoptera polyphagous suborder Tianniu family, and is an important pest of street trees, shelter forests, garden parks, factories and mines, schools, and green trees. Its main growth insect period lives in the trunk of the tree, with a chewing mouthpart to feed on the phloem, xylem and the formation of layers of moth adult tract, destroying the tree nutrient and water channeling function and meristem, light tree growth is weak, heavy tree rapid death, is a type of pest that is very easy to destroy the forest.
At present, there are more than 20,000 known species of Tianniu in the world, and more than 2,000 species have been recorded in China, of which more than 200 species are distributed in Shaanxi Province. The Yellow Spot Star Celestial Bull, bare-shouldered Celestial Bull and Qingyang Tianniu are prone to disasters to tree species such as poplar, willow, elm and maple trees. Poplar trees are the main afforestation tree species in shelter forests, and the area affected by tianniu exceeds 10%, which seriously restricts the production and development of forestry. In order to protect forest resources and give full play to their social, ecological and economic benefits, it is imperative to do a good job in the prevention and control of Tianniu.
<h1 class="pgc-h-arrow-right" >1 Causes of Tianniu hazards</h1>
(1) The hazard process of Tianniu is extremely hidden, so it is difficult to control: in the entire life cycle of Tianniu, except for adult insects, they live inside the trunk, are less affected by the external environment, and the growth of the affected trees in the early to middle stages of the victim is not significantly affected, so it is not easy to perceive. Even if found, chemicals are difficult to play a role, so it is difficult to control.
(2) The increase in the area of artificial pure forests causes rapid spread after the occurrence of insect pests: the Three North Shelter Forest and the farmland forest network have a single species, mainly poplar trees, resulting in large-scale occurrence of diseases and insect pests.
(3) Extensive operation and management: Due to the lack of management and management, the tree is weak, which provides conditions for the occurrence of Tianniu.
(4) Few natural enemy resources: The natural enemies found at present are extremely limited, and biological control is limited, which can only be used as an auxiliary means when the insect population density is small.
(5) There are many ways of transmission: the area of forestry production is increasing, and the transportation activities are quite frequent, which spread with the carrying of materials such as seedling wood scion.
<h1 class="pgc-h-arrow-right" >2 Common types and hazards of celestial cattle</h1>
In addition to the yellow-spotted star tianniu, the bare-shouldered star tianniu, the qingyang tianniu and the mulberry tianniu, etc., the guanzhong multi-haired tianniu is a species with poplar, willow, elm, etc. as the host, with the improvement of road greening, the increase of green area, and the growth of tree species, other types of tianniu such as peach-necked tianniu also occur.
2.1 The harm of the Macular Star Celestial Bull
The Macantula star tianniu is a pest that feeds on poplar trees, mainly feeding on the trunks of poplar trees with larvae. Many large wormholes will form in the xylem of the damaged tree, and many worm lanes will form inside the trunk. In such cases, the trees will wither, break, and in severe cases, even die.
2.2 The harm of the bare-shouldered star Celestial Bull
May to June is the peak of activity for the bare-shouldered celestial calf larvae, and June to September is the feathering period. The damage of this kind of celestial bull is mainly based on the damage of larvae in the main trunk or main branch of the tree. These larvae will moth the phloem of the trunk, and moth into irregular curved worm passages in the xylem of the trunk, and will moth small holes in the worm tunnel, excreting feces and wood chips from the holes. In fact, this kind of tianniu has a loose choice of the age of the host tree, and the harmful parts have their own emphases. For example, for young trees, it is mainly harmful to the trunk; for middle-aged trees, it is mainly harmful to the main branches, especially at forks.
2.3 The harm of Qingyang Tianniu
The Poplar Ox is a widely distributed pest that mainly affects poplar branches through larvae. The hazard time is generally from late May to early October. Under the hazard of this pest, the branches of the tree are easily dried up and broken, and the canopy will be deformed and bald, which will affect the growth of the wood.
2.4 The harm of the Mulberry Bull
Mulberry cattle appear in many areas, mainly through mulberry trees to supplement nutrition, while the larvae are mainly harmful to poplars, elms and so on. From July to August every year, it is the occurrence period of adult mulberry cattle. Adults usually feed at night, and lay their eggs in the middle or at the base of branches with a diameter of 10 to 15 mm. In the process of spawning, the epidermis of the branch is usually first bitten. Small mouths are formed, and eggs are laid in them, and the insects spend the winter in the branches. The larvae will keep mothing the moths in the branches, all the way to the roots of the moths, and at intervals a small hole will be made outward for ventilation and feces. This kind of celestial bull will cause the tree to weaken and break easily.
<h1 class="pgc-h-arrow-right" >3 Guanzhong Tianniu control technology</h1>
In the prevention and control of Tianniu, it is necessary to follow three principles: prevention first, scientific prevention and control, and governance according to law.
3.1 Lay a solid foundation and do a good job of control from the aspect of camp forestry
Start from afforestation design to do a good job in prevention, actively choose to create mixed forests, select disease-resistant insect tree species and indigenous tree species. The seedlings of afforestation must be good seedlings. When planting trees, it is necessary to operate in strict accordance with technical specifications to ensure that they thrive in the later stages. During the growth period, we should do a good job in the care and management of trees, and enhance the tree potential, reduce the source of insects, and reduce the harm by removing germinated branches, insect pests, weakening trees, carrying gall branches and regular fertilization.
3.2 Do a good job in prevention and strictly implement quarantine measures
For quarantine objects such as the Yellow Spot Star Tianniu and the Double-striped Fir Tianniu, quarantine is done in strict accordance with the quarantine operating procedures to reduce human transmission. On the one hand, external quarantine. Strict quarantine of forest products such as host logs (including plates and square materials), seedlings and packaging materials with live bodies transferred from other places is strictly quarantined to prevent the entry of insects from outside. On the other hand, internal quarantine. Internally, strict quarantine should be carried out at wood processing and sales points, stations, timber storage yards and seedling breeding bases to prevent the spread of insect-bearing wood outwards.
3.3 Maintain ecological balance and adopt biological control methods
Biological control is the use of natural enemies of organisms in the biological chain for prevention and control, which is not only efficient and pollution-free, but also fully in line with the development law of the ecological environment. The application of biological control technology can be considered from two directions; 1) from the perspective of predators, focus on planting the trees that Tianniu likes, and then concentrate these Tianniu in some areas, so as to carry out centralized extermination treatment; 2) from the perspective of predators, the use of insectivorous beneficial birds to prey on Tianniu can also achieve the purpose of reducing the number of Tianniu. In the forest and some shelter forest lands in areas where the population density of Tianniu insects is not high and the impact of human factors is small, the commonly used biological control method is to artificially attract woodpeckers. Pay attention to controlling the number to prevent the occurrence of secondary disasters. In the forest area, the density of woodpeckers is controlled at 500 m²/pair, which can effectively control the Tianniu disaster and will not cause secondary disasters.
3.4 Protect the ecological environment and use artificial hunting for prevention and control
Due to the obvious and easy to observe the harmful characteristics of Tianniu larvae, the concentration of spawning, the characteristics of adult life habits and the relatively large and easy to catch individuals, it is easy to carry out artificial control. In the larval hazard period, when it is found that there is fecal debris on the trunk, the larvae can be peeled off and the larvae can be peeled off, and killed or stabbed to death in the moth tunnel with a metal wire; the adult insects occur at their peak, using its "suspended death" or habitat at the base of the trunk for artificial hunting; at the egg stage, look for adult insects to lay eggs and smash eggs or combine tree tube protection to shear the gall, thereby effectively reducing the density of the insect population.
3.5 Timely reduction of harm, the use of chemical drugs to prevent and control Tianniu
Drug control as an auxiliary means, is a kind of emergency measures in the acute occurrence of insect pests, in the case of unavoidable use, in order to promote the healthy development of forest resources, should be rational use of drugs, strict control of drug dosage, accurate grasp of the time of medication and method of application, in order to effectively control the insect situation. At present, common drugs for the prevention and treatment of Tianniu are 40% Lego emulsion or 40% oxidized Lego emulsion, 50% octinophosphorus emulsion, 50% borer pine emulsion, 90% dimethods crystals and so on. In the specific operation, according to the actual situation, choose to use pesticides by mechanical spraying of drugs or artificial injection of drugs into the borer hole or insertion of poison sticks, so as to avoid the waste or pollution of drugs as much as possible, and control the insect situation as soon as possible and reduce the harm of Tianniu in time.
Because Tianniu mainly pests larvae, according to the damage site of the larvae, different agents are selected and different application methods are used to send the medicine in place. Here's how:
1) Small and medium-aged trees with low hazards or low hazard sites can inject drugs directly into the moth;
2) Tianniu with higher harm parts, when Tianniu is still harmed in the phloem part, inject medicine at the base of the trunk, carry it to the upper part through the tree transport tissue, in order to kill the larvae that are harmful in the phloem;
3) Subcutaneous larvae, spray directly on the trunk;
4) Peach-necked tianniu and other tianniu that harm the roots can be irrigated with pesticides;
5) Mulberry cattle and other larvae fed downwards and have fecal holes, which can be fumigated with aluminum phosphide and other plugged holes;
6) The use of drugs in the adult stage is mainly based on spraying pesticides on the trunk of the tree during the nutritional stage and before spawning, or directly killing the adult insects or preventing them from laying eggs
< h1 class="pgc-h-arrow-right" >4 conclusion</h1>
Forest resources are important resources on the earth, and the intensification of forest pest disasters, especially the aggravation of the harm of tianniu, not only affects the normal growth of trees, but also affects the quality of wood. It not only affects economic benefits, but also affects its ecological and social benefits. Therefore, only by adapting measures to local conditions, classifying policies, starting from the protection and improvement of the environment, and adopting scientific and reasonable prevention and control measures can we achieve the effect of treating both symptoms and root causes, so as to increase the protection of forest resources and achieve sustainable development.