1. Garden plant pests are the main research direction of biological control
The introduction of natural enemies has been carried out for more than 100 years, and its full potential has not yet been realized. The use of traditional biological control is an effective means to control foreign pests. According to statistics, since 1900, 70% of pests in the Netherlands are foreign. There were at least 837 species of alien insects established in the United States from 1920 to 1980, of which 10% have become serious pests. It is estimated that there are 500,000 species of parasitic Hymenoptera in the world, but only less than 50,000 species have been described. The potential for biological control is less than 10%. The success of traditional biological control is directly proportional to the efforts made by the introduction of natural enemies. my country has established natural enemy exchange relations with more than 20 countries and regions. The aphid bee and the aphid gall midge were introduced from the UK and Canada respectively. These two natural enemies have shown good control power in the control of whiteflies and aphids in Chinese garden plants.
As people learn more about natural enemies and improve their selection, production and transplantation techniques, the success rate may actually be greater than what has been in history. Through greater efforts from all aspects of society, traditional biological The chance of success in prevention and control will increase significantly. Of course, it should be recognized that biological control is an important part of integrated pest management (IPM). The greatest contribution to IPM is not through introduction or inoculation, but the protection and utilization of local natural enemies in the garden plant system. With the passage of time and the accumulation of knowledge and experience, natural biological control will also be better applied.
2. Special management of natural enemies
The management of natural enemies is one of the most neglected areas in biological control and one of the most promising areas. The special management of natural enemies may be regarded as an important aspect of biological control. The improvement of mass reproduction technology, the application of artificial feed and a deeper understanding of the ecology of natural enemies are the basis for the successful use of natural enemies. A particularly promising method is to regularly transplant natural enemies, expand their range, and develop into a plant environment. Feeding management methods designed to retain and expand their populations. The innovation of production technology, the application of artificial feed or the improvement of other habitats, the accurate arrangement of release time and the application of more effective natural enemy species or strains will greatly improve the effect of regular transplantation. Studies in the United Kingdom and Europe have shown that this technology has great potential for biological control of greenhouse pests. Many plants with high economic value and pest problems in parks and courtyard gardens should also be solved in accordance with regular transplantation techniques. At present, some large chemical and pesticide companies have begun to allocate funds to scientific research units to carry out research on the artificial breeding of natural enemy insects and the mass reproduction technology and the industrialized commercial production technology. In fact, certain companies that traditionally produce pesticides in Japan and Europe have already produced natural enemy products on a certain scale.
At present, our country has developed a new method for the industrial production of Trichogramma. The daily production of Trichogramma is 700 to 800 million, which can be used to control pine caterpillars, moths, leaf rollers, leaf roller moths and other garden plant pests. my country has become one of the countries with the largest area of bee pest control in the world. At present, the natural enemies of my country's commercial production include Zhou's mites, Aphids, Platy-bellied mites, ladybirds, lacewings, and predatory mites. It has played a very important role in the prevention and control of garden plant pests.
3 Utilization of insect pathogenic microorganisms
There are more than 1,000 species of insect pathogenic microorganisms. These microorganisms are harmless to humans, animals and plants, and can be used to control pests. The use of microorganisms to control pests has the advantages of wide application range, long-lasting virulence and convenient use. Many cities in my country have accumulated rich experience in carrying out microbial pest control.
3.1 Utilization of pathogenic fungi
There are many species of entomogenous fungi that cause insect diseases, about 405 species. The main researches on it and the greater practical value are Entomophthora in the algae, Beauveria bassiana, Metarhizium anisopliae and Verticillium lecanii in the imperfect fungus. Beauveria bassiana is known for pine caterpillars, and Metarhizium anisopliae is known for controlling lawn grubs. Entomophthora is an important pathogenic fungus of aphids. Entomophthora tuberosum is a cultivated strain of pathogenic fungus and its secondary metabolites, which have a good control effect on garden plant aphids. Verticillium lecanii is commonly used to control whitefly, aphids and mealybugs in greenhouses.
3.2 Utilization of Bacillus thuringiensis
Bacillus thuringiensis is also known as B.t. insecticide. At present, more than 50 variants of 23 serotypes have been found, which is the most widely used type of microbial pesticides. B.t. insecticides are widely used in China: Tianmen varieties, Wuhan varieties, wax moth varieties, Suyunjin varieties, etc., and are often used to control sky caterpillars, loopers, tussock moths, pine caterpillars, nest moths, citrus swallowtails, etc. Bt preparation is the most widely produced biological preparation in the world today. The product has a certain commercial life, but its field stability is still not ideal. Various factors of climate and plant itself will affect the persistence of Bt toxin protein in the field. Effectiveness. The alternation of wet and dry climates, proteases in the preparation or the drug-receiving parts of the plant, and sunlight will all cause the degradation of Bt toxin protein. In order to maintain the activity of the toxin protein of Bt products and prolong the residual effect, microencapsulation technology has been developed. This technology is to clone and express the isolated Bt toxin gene in Pseudomonas fluorescens. After Pseudomonas fluorescens has been fermented, a certain technology is used to kill its living cells, so that the dead cells are obtained. The wrapped Bt toxin protein microcapsule product can protect the toxin protein from external conditions.
3.3 Utilization of insect viruses
Viruses are organisms smaller than bacteria, and they are highly specialized and cannot survive without the host. They must be cultured in vivo. There are more than 500 kinds of insect viruses that have been discovered. my country is rich in insect virus resources. 234 pathogenic viruses have been isolated from 33 species of insects in 7 orders, providing precious natural resources for the development and production of insect virus insecticides. There are two main types of insect viruses used to control pests, namely nuclear polyhedrosis virus and granulovirus. These two types of viruses can control major pests such as aphids, canopy caterpillars, loopers, tussock moths, pine caterpillars, nest moths, diamondback moths and cotton bollworms.
3.4 Utilization of Entomopathogenic Nematodes
Entomopathogenic nematodes are filamentous parasites that live in insects. There are many kinds of about 5000 kinds. Pathogenic nematodes are widely distributed in nature, and they are parasitic in a variety of garden plant pests. As long as the host's conditions are suitable, it can survive and multiply. Such as peach small heartworm, small roll moth, small cutworm, prodenia litura, long beetle, etc., all have nematode parasites. Research on the use of pathogenic nematodes in my country has become more active in recent years. At present, the most widely used Nematode Nematodes can control Lepidoptera, Diptera, Coleoptera and other different pests, and have good effects. Especially after artificial mass reproduction, it is released in the field, the effect of controlling pests is better, and its parasitic rate is often as high as 85%.
4 Antibiotic insecticide
Antibiotic insecticide is a biological agent developed in the past ten or twenty years. They are mostly biological secondary metabolites, which can be artificially synthesized, and some have entered the stage of factory production and mass application. Insecticidal antibiotics show different characteristics from chemical pesticides, mainly: ①The use of low concentration, the killing effect is greater than the preventive effect. ②Antibiotics mainly come from a variety of microorganisms, and the sources are very wide. ③Antibiotics are generally used in small amounts, which are easy to transport and can be mixed with a small amount of chemical pesticides. This is the basis for its easy promotion and use. Commonly used insecticidal antibiotics in the prevention and control of garden plant pests are Liuyangmycin, Huaguangmycin, Spinosad, Abamectin, Spinosad and so on. Among them, abamectin is a kind of high-efficiency, broad-spectrum, insecticidal, acaricidal and nematicidal activities of macrolide insecticidal antibiotics. It is the most widely used in the prevention and control of garden plant pests. Abamectin can be used to control citrus rust mites, panonychus citrus, orange shoot gall mites, short hair mites orange, Tetranychus japonicus, tea semi-attached line mites, and vector-pointed shields. Scales, leaf miners, alfalfa thrips, small tube aphids, green peach aphid, flower mites, buckler scales, tobacco armyworms, hawk moths, etc., are very versatile. Spinosad is also a commonly used antibiotic insecticide, mainly used in ornamental plants to control nematodes, beetles, thrips, leaf miners and many other pests. The dosage is 12g～15g/ha. It is considered to be the most effective insecticidal antibiotic after abamectin.
5 Utilization of insect sex pheromone
Various insects in nature can release trace chemical substances with specific odors to attract insects of the same sex to mate. This chemical substance that plays a role in communication during the mating process of insects is called insect sex pheromone or insect sex pheromone. Sex pheromones or analogues used to control pests can be called sex attractants, or sex attractants for short. Sexual attractants have two unique advantages: one is specificity. The sex pheromone of the diamondback moth can only attract the diamondback moth, but not other insects. This effectively protects the numerous natural enemies in nature. Second, the secretion has a certain period of time, and the insects can only secrete sex pheromones when they are sexually mature. Based on this, the peak period of attracting moths can be found. This can be used to trap and kill adults directly in production practice and improve the effect of pest control.
According to the current understanding, insects use sex pheromones to enable them to accurately find the insect species of their mates, including Lepidoptera, Coleoptera, Hymenoptera, Diptera, Homoptera, and Orthoptera. There are more than 2,200 insect pheromones that have been identified and synthesized. In my country, sex attractants have been used for peach-striped wheat moth, apple leaf roller moth, Japanese beetle, olive fruit fly, gypsy moth, European pine stalk moth, sophora japonicus, corrugated beetle, Mediterranean wax fruit fly, and diamondback moth. In the control of garden plant pests.
6 Development prospects of plant pesticides
Plant insecticides are insecticides made by using certain parts of plants with insecticidal activity or extracting their active ingredients. It is a safe and economical insecticide developed on the basis of research on the effective ingredients of insecticidal activity possessed by some plants. It is a plant biochemical substance. At present, my country has developed and registered more than 20 varieties, mainly including neem, chrysanthemum, anisin, pyrethrum, veratrine, nicotine, matrine, celangulin, cineole, etc. . It is used to control aphids, caterpillars, looper, tussock moths, pine caterpillars, nest moths, small curlers, cutworms, spider mites and other pests.
The characteristics of plant-derived insecticides are summarized in the following aspects: (1) Local materials are used and it is convenient to use. Plant pesticides are rich in resources and can be used after collection or directly processed into preparations or extracted effective ingredients to be processed into preparations. ② It is safe to plants and generally does not cause phytotoxicity. ③Easily degradable, short residual effect period, and basically no pollution to the environment and food. ④Different plant-derived insecticides have different effective ingredients and insecticidal mechanisms. In-depth research can find a direction for the development of a new class of insecticides. ⑤The resource of plant pesticides is complex, and it must be used on the basis of in-depth understanding. ⑥ At present, many plants of plant-derived pesticides rely on artificial cultivation, and there is a problem of land competition with agricultural production.
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