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In China, the development of botanical pesticides

2018-02-11 19:48:36

The mainstream of botanical pesticides research lies in the exploration of bioactive lead compounds for the creation of new pesticides. This is a work that requires deliberate innovation and the pursuit of original innovation. The goal of innovation lies in two aspects: one is to obtain novel chemical compounds with pesticidal activity; the other is that the compounds are known but their activities are novel or have not been reported. Pesticide research is a biological and chemical close Combination of topics, biological research unit has the advantages of bio-measurement, and chemical research unit has the advantages of basic research such as extraction and separation and structure identification, if the two sides can strengthen cooperative research, will achieve the purpose of complement each other to promote plant resources Pesticide research is very beneficial. I believe in the future of pesticides, plant-based pesticides will occupy an important place, to contribute to agricultural production

Pesticides play a very important role in agricultural production. With the improvement of people's health awareness, the country is a big agricultural country. Most countries attach great importance to the safety of agricultural products, and the restrictions on pesticide residues are very strict. After China's accession to the WTO, agricultural products importation faces a very serious green barrier. "Pesticide residues exceeding the standard are often encountered problems, seriously affecting the competitiveness of agricultural products in the international market.In order to reduce pesticide residues, efforts to develop new types of pesticides have become Top priority.

Degradable in nature, plant-derived pesticides come from nature. Generally does not pollute the environment and agricultural products, the environment and the human body is not likely to accumulate toxicity, relatively safe to humans and livestock, harm to pests and natural enemies, pests and their difficult to produce antibodies, with low toxicity, low residue characteristics, To adhere to the high quality of agricultural products, plant-derived pesticides have a vast market. In the recent two decades, lots of manpower and material resources have been invested in the development and research of plant-derived pesticides. In this respect, I also made some useful attempts to extract a strong bactericidal antiviral from the roots of a tree coniferous plant Of the active substance, the field experiment showed that its high efficiency and low toxicity, has good development prospects. In this paper, we reviewed the active ingredients and mechanism of plant-derived pesticides and provided references for the research in this field.

First, the active ingredient of plant-derived pesticides

In addition there are lignans, botanical pesticides active ingredients can be divided into alkaloids, terpenes, ketones and annona lactones. Such as ethanolamine; nests, such as bovine lactone; hydroxy acids such as pyrethrins and the like. This article mainly summarizes the above four categories.

Alkaloids

Has been proved to kill the main role of pests nicotine, camptothecin, berberine, veratridine, matrine, triptolide, small strychnine, tetrandrine, Sophora albumen and so on. There are more than 6,000 kinds of alkaloids found in these kinds of insects. Such as poisoning, antifeedant and avoidance and inhibition of growth and development.

2. Terpenes

The majority of essential oils are terpenes. At present, the terpenes found in plant-derived pesticides are mainly monoterpenes, sesquiterpenes, diterpenes and triterpenoids. Terpene compounds are plant-source pesticides in more content, more extensive study of a class of compounds.

The main mode of action for pests smoked kill effect. The main monoterpenes are the effective insecticidal ingredient terpinen-4-ol in the cypress leaves of the cypress plant.

There are a variety of β-dihydro-fructose furanose sesquiterpene-based polyol ester; Bitter bark root bark insecticidal activity of nearly 20 α-dihydro-furan compounds. The compounds kill pests mainly through antifeeding, stomach poisoning, systemic absorption and reproductive behaviors that affect spawning and hatching of test insects. Sesquiterpenoids have a horse Sango plants contained in the horse Sango Ma Sang toxic B Wechsler plants contain more sesquiterpenoids.

In addition there are the main insecticidal active ingredients in the school of Argyrophila-III. The main mode of action of these compounds are antifeedant, poison kill and inhibit larval growth and development. Diterpenoids mainly Euphorbiaceae Euphorbia, croton and Daphne species diterpene diterpenoid compounds.

Of 200 kinds of pests have different effects. It has also been reported that the main mode of action of rutaceae plants containing triterpenoids Severinolidel3Atalantinl4 and Cycloepiatalantinl5 triterpenoids is antifeedant effect. Triterpenoids have the world's most recognized insect repellent Indian Neem's main active ingredient azadirachtin.

As the active ingredient of plant-derived pesticides are peppermint oil, eucalyptus oil, cinnamon oil, Artemisia artemisiae oil, oil and other oil. Essential oils kill pests primarily through the action of smothering. More research on essential oils.

3. Ketones

Flavonoids glycosides or aglycone, bixoglycoside or trisaccharide glycosides exist with the role of pest control mainly rotenone, hair rotenone and so on. The mode of action is antifeedant and poison killing effect.

4 Annona lactone

Compared with the types of natural products found in the past, there is a big difference between the types of pericarps, which is one of the characteristic bioactive components of Annonaceae. From 35 to 39 carbon atoms constitute the skeleton of the compound, the molecular tetrahydrofuran ring and terminal γ-lactone ring through the carbon chain connected to the carbon chain often with hydroxyl, keto and acetoxy and so on. Annona lactone exerts its insecticidal activity through its strong gastric and antifeedant effects. Studies have shown that it is more effective than the world-recognized high efficiency plant-derived pesticide rotenone and organophosphorus pesticide acephate.

Second, the mechanism of plant-derived pesticides

Many of these secondary metabolites show toxic effects on insects, behavioral disturbances and biological developmental regulation. As the secondary metabolites are the result of synergistic evolution between plant self-defense and insect adaptive evolution, the insecticidal active ingredients in plant-derived pesticides are mainly secondary metabolites. Insects are not resistant to them. The results showed that plant-derived pesticides have unique effects on pests and diversified modes of action, and the mechanism of action is complex. In summary, they are mainly toxic, antifeedant and repellent, interfering with normal growth and development and photoactivation.

1. Poisoning effect

Plants on the most direct insect, the most effective way is to kill poison effect.

① stomach poisoning effect

Toxic substances have the stomach poisoning can damage the insect's midgut tissue, toxicology studies have shown. So that the midgut subcellular structure changes, but also block the nerve conduction of insects, inhibit a variety of detoxification enzymes, play a nerve agent. Symptoms of stomach poisoning for the parasites dehydration shortened, drooping stool, and even pulled out the rectum or vesicles until death.

② touch effect

Express excitement, pests exposed to the role of contact with the material. The nerve center is anesthetized, and the pest protein coagulation blocked the pores of parasites so that the pest suffocation death.

③ smoked effect

Essential oils peel epidermis wax layer arrangement of particle changes, most of the essential oils have a smothering effect. Destroy the midgut tissue, inhibit the central nervous system self-release. In view of the special way fumigation, essential oils can be used to control storage pests and greenhouse pests.

④ inside the poison kill effect

Compared with the spray, systemic action is a special stomach poisoning. This way of environmental pollution is small, easy to kill natural enemies. Many botanical insecticidal substances have typical systemic toxicity.

2 antifeedant and avoidance effect

But to allow it to exist but forcing the pest to shift to choose the target. Any biological behavior is to accept information in vitro and in vivo, with the role of antifeedant and repellent substances do not kill pests directly. The result of a comprehensive reaction between the nervous system and the muscular system can be regulated by foreign chemicals. A substance that has antifeedants and repellent effects is to alter the information of the pests in and outside of the body, and then affect the nerves, forcing the pests to act as counterfeits and avoidance.

3. interfere with the normal growth and development

So that eggs can not hatch properly, many plant-based pesticides can interfere with the growth and development of pests. Larvae can not normally molting pupae, pupae can not be normal emergence or deformity, pests play a dominant role in the entire growth process. It is currently believed that the active ingredient is interfering with the normal endocrine system of insects, resulting in abnormal growth and development. This mode has less obvious effect on pests of the current or current year, but can control the next generation of pests.

4. Photoactivation poisoning effect

Photosensitizers are the key to photoactivation. The currently accepted mechanism is photodynamic and photoinduced toxicity, photoactivation poisoning is the active ingredient of plant-derived pesticides with the help of photosensitizers. Namely, the photo-sensitizer takes photons of a certain wavelength and generates free radicals or induce singlet oxygen to attack biological macromolecules such as lipoproteins, enzymes and nucleic acids and the like, resulting in the death or damage of pests.

Third, the conclusion

The development and utilization of plant-derived pesticides have unique conditions, rich plant resources. Some achievements have been made on the research and development of plant-derived pesticides. Saponin nicotine-soluble emulsions, rotenone emulsifiable concentrates, bovine serum-base agents, fenugreek extract, oleic acid nicotine, Registration, and a small-scale commercial production. However, compared with similar studies in the world, there are still some differences on the overall level. In recent years, most of the units engaged in the production of plant-derived pesticides in China are mostly small local factories. Most of the products are water-based or creamy oil, and so far no scale has been formed. There are two main reasons: First, the basic research on plant-based pesticides to invest too little, it is not clear what kind of plant material is the main active ingredient, only the total extract expressed and reflect the efficacy of their products ; Secondly, the research on the pharmacodynamics of plant-derived pesticides is limited, and the direct use of active ingredients is relatively low. The active ingredients on the market are only a few parts per million, and some are even only a few percent. For this situation, the domestic plant-based pesticides need to strengthen basic research, improve product quality, comply with international trends.

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