Since the discovery of the first case of pine wood nematode disease in China in 1982, it has spread rapidly in the southern provinces of China, and at present, 16 provinces and cities such as Jiangsu, Zhejiang, Anhui and Gansu have successively discovered and confirmed the pine wood nematode epidemic, and almost none of central China, East China and South China have been spared, and the harm is extremely great, and nearly 10 million mu of pine tree resources are frequently in the face of catastrophe, which poses a devastating hazard to pine tree resources.
<h1>Characteristics of pine wood nematode disease</h1>
Pine wood nematode disease, also known as "pine tree atrophy disease", is a kind of pine wood infected with pine wood nematodes, pine wood nematodes in the pine tree body in large numbers of reproduction, resulting in pine trees normal physiological activities are harmed and damaged, pine resin secretion is significantly reduced or stopped, photosynthesis weakens, transpiration declines, pine needles quickly lose green, yellowing, wilting, color gradually from green to yellowish green, yellowish brown and finally become eye-catching reddish-brown, hanging branches do not fall, like symptoms after the fire, so pine wood nematode disease is also known as "non-smoke forest fire".
At the same time as the pine needles change significantly, the damage characteristics of moths such as borer holes, wood chips, and insect feces can be found in the trunks and trees of pine trees, which are traces of the activities of the insect pine brown tianniu, a vector of pine wood nematode disease.
The section of the trunk of the dead dead pine tree that has fallen down will have a ring of blue-gray to light blue spots, and it is very obvious.
<h1>Pathogenesis of pine wood nematode disease</h1>
For the pathogenesis of pine wood nematode disease, according to relevant studies, there are currently three views.
Enzyme theory: after pine trees are infected with pine wood nematode disease, pine wood nematodes in the body can secrete a variety of enzymes, of which one enzyme is crucial, that is, fibroase, which can break down the cell wall of pine cells, causing pine trees to be fatally injured, wilting and dying;
Toxin theory: After the pine tree is infected with pine wood nematode disease, due to the multiplication of pine wood nematode, a toxin will be produced, and it is this toxic substance that causes the pine tree to wither and die.
Cavitation theory: After pine trees are infected with pine wood nematode disease, the content of terpenes (a hydrocarbon in the plant body) and timesterpene in the body surges, entering the tube cell tissue of the pine tree, forming a cavity, which blocks the normal water transport of the pine tree, resulting in the wilting and death of the pine tree.
<h1>Route of transmission of pine wood nematode disease</h1>
Pine wood nematode disease is caused by pine wood nematodes, pine wood nematodes are a very small live worm, observed under the microscope, it is worm-shaped, only 1 mm long, the worm body is slender, and does not have the ability to spread, so how does the pine wood nematode spread?
It turns out that pine wood nematodes are attached to the surface of vector insects, with the help of vector insects to achieve cross-regional transmission, and constantly spread wildly, this vector insect in China is the pine brown tianniu.
In general, the pine brown tianniu is very fond of invading the pine tree in the semi-withered state, because the pine resin secretion is small, the material is loose, easy to moth holes, and this pine tree is mostly the source of the disease that has been infected with pine wood nematode disease, with the death of the disease source wood, the pine brown tianniu completes feeding, supplementing nutrition, mating and spawning, wintering, larva hatching, the next year 5-7 months larvae feathering, a large number of take-off migration, looking for new pine source, will once again endanger other healthy pine trees, so repeated invasion, infection, spread, Causes the rapid spread of pine wood nematode disease.
Therefore, the key to the prevention and control of pine wood nematode disease is the pine brown tianniu, as long as the breeding and migration of the pine brown tianniu can be controlled, the spread and spread of pine wood nematode disease can be controlled. #谷丰计划 #