Abstract: An overview of the application of tea saponins in the field of pesticide industry is summarised and possible avenues for future development are suggested. The mechanism of action of tea saponin applied in pesticide industry is discussed in the paper, which proves that tea saponin is a kind of natural surfactant suitable for pesticide industry in terms of its surface tension, contact angle and wettability. Practice has shown that tea saponin as a wettable powder pesticide wetting agent, can make wettable powder pesticide wettability, PH, suspension rate and other indicators can meet or exceed the national standards. Tea Saponin in emulsifiable concentrate pesticides, can be used as synergistic, spreading agent, improve the effect of pesticide application. Tea Saponin in herbicides soluble powder, water application can improve product quality and application effects, the overall level is better than similar foreign products. This paper also introduces tea saponin as a biopesticide in aquaculture as a clearing agent, crop and vegetable farming as insecticide, fungicide, snail killer:
Keywords: Tea Saponin, Pesticide Industry, Pesticide Additives, Biopesticides
Classification Number: TQ450.4+5 Literature Identifier: A
Progress on the Research Field of Tea Saponin
Since 1979, tea saponin industrial products for the first time in the Chinese Academy of Agricultural Sciences Tea Research Institute, twenty years in the basic research [1-3], quantitative methods [4-5], application development and industrial product series have been greater development.
Basic research [1-3], quantitative methods [4-5], application development and industrial product series have greater development, while the establishment of a number of professional manufacturers or production, the application has been expanded to light industry, chemical industry, building materials, aquaculture, as well as medicine and health care industry, and has a number of independent intellectual property rights of technology patents and inventions: tea saponin in the pesticide industry, whether in theory Tea Saponin in the pesticide industry, both theoretically and practically are relatively mature, the scope of application has been expanded to all areas of the pesticide industry, and formed a considerable scale. According to the analysis of existing research results, tea saponin in the pesticide industry in the scope of application can be divided into four categories: one is in the solid-type pesticides as a wetting agent and suspending agent; two is in the emulsion-type pesticides as a synergist and spreading agent; three is in the herbicide class of pesticides or pesticides slightly soluble in water as a co-solvent; four is directly as a biopesticide, and so on.
1, tea saponin applied to the pesticide industry’s role in the mechanism 1.1 tea saponin wettability Wettability is one of the main technical indicators of pesticide wetting agent, but also the main quality standards of wettable pesticide powder. Xia Chunhua et al. (1990) using JY-82 contact angle meter, and paraffin board as a carrier, the tea saponin wetting performance test results show that tea saponin has a wetting effect, the size of the role of the concentration is related. The contact angle of water is 108 °, for attachment wetting, with the increase in the content of tea saponin in solution, the θ value will no longer decline. When the concentration is around 1 per cent, θ decreases to below 90°, which is impregnation wetting. In the determination of 0.001%-10% range, θ value and its concentration of the logarithm of the negative correlation, y = 90.81115-5.897x,r = -0.98042. On this basis, tea, oil tea and soap pods of three kinds of plant saponins of the wetting properties of the pesticide analysis by the determination of the speed of wetting used in the comparison of the results of the tea saponin’s wetting performance is better than the oil tea saponin.
1.2 Tea Saponin surface activity Xia Chunhua (1990) used to pull the film method of surface tension of tea saponin aqueous solution of the results, tea saponin can significantly reduce the surface tension of the liquid. It indicates that it has a surface-active effect. The size of its role with the tea saponin solution concentration, when the concentration of 0.001% – 1.00%, the surface tension with the increase in concentration and decreased from 76.85mN / m to 46.735mN / m, which is an aqueous solution of tea saponin in the region of 0.5% of the surface tension is the lowest, and then the concentration of tea saponin and then increased, the surface tension is no longer reduced, but there is a tendency to increase. On the contrary, there is a tendency to increase.
Surfactant aqueous solution of this rule of change, can be said to be a generality, the reason with the molecular structure of the above two groups. When the concentration of active substances is too low, the water surface can not be covered by the surfactant, the surface tension has decreased, but not the lowest. With the increase of the concentration of active substance, the active agent molecules on the surface of water increases, the surface tension gradually decreases, when it increases to the liquid surface to form a layer of single molecule film, this time is called directional adsorption, the liquid surface is all replaced by the hydrophobic group of the surfactant, the surface tension reaches the lowest, even if it increases the concentration of active substance, the surface tension no longer decreases, the same phenomenon of directional adsorption exists in the liquid – liquid system interface, the decrease of surface tension is the lowest. –This directional adsorption phenomenon also exists at the interface of immiscible liquid-liquid system, which reduces the interfacial tension. This is an important limit, the concentration of active substances in the solution surface has reached saturation, can not continue to increase, known as the critical micelle concentration, customarily expressed in CMC. If you continue to increase the surfactant content, it will be retained in the solution inside, to “micelle” state gathered in one place, the molecules are not dispersed, to the critical micelle concentration as the limit, many physical properties of the solution in this significant changes. Surface tension, interfacial tension, density, electrical conductivity and washing performance are related to this, in addition to osmotic pressure, freezing point drop, viscosity, ionisation, solubility and light scattering and so on and this effect. Strictly speaking, the critical micelle concentration of each surfactant function has a certain range, called the critical micelle concentration range. The critical micelle concentration of tea saponin was determined by surface tension assay, and the results showed that the CMC of tea saponin was around 0.5%. In order to confirm the effect of water hardness on the surface activity of tea saponin, aqueous solutions of tea saponin of different hardnesses were prepared using standard methods for comparison. The hardness of water from 0 ° – 28.7 ° d, that is, from very soft water to very hard water, the measured surface tension between 45.73-47.13, the difference is very small, the absolute value of the highest and lowest difference of only 1.45mN / m, it can be said that the surface activity of tea saponin is almost unaffected by the hardness of water.
2.2 As an emulsion-type pesticide synergist and spreading agent Tea Saponin in the emulsion-type pesticides in the application of research and reporting is relatively small. Because tea saponin in emulsifiable pesticides in the difficult to dissolve, the need for solubility; and then the synergistic effect of pesticides only on the use of favourable aspects of the pesticide enterprises to increase the profit is not obvious. So the scope of the current promotion and application is not large.
In fact, the significance of pesticide efficiency is great. It is a directional problem. According to Hu Shaohai research [7-9], tea saponin and methomyl, kung fu pyrethrin, pyridaben and other emulsifiable pesticides used in the matching, the effect is very good, and can reduce the amount of pesticides, favourable to environmental protection. The co-toxicity coefficient is 733.1~6279.7, and the multiplier of synergistic effect is 6.33~61.8, which saves pesticides by 50%~70%. As for the reason that tea saponin can make pesticides more effective, according to Wang Xiaoyi [10], it mainly reduces the surface tension of the liquid; makes the droplets of the liquid in the body surface of plants and pests contact angle has been reduced, thus improving the wet spreading force and adherence of the liquid in the body surface of the target to reduce pesticide loss and improve the efficacy of pesticides.
2.3 As a co-solvent of herbicides or soluble powder pesticides
These pesticides are generally difficult to dissolve in non-polar solvents, but can be dissolved in polar solvents or water. Some can even convert the original drug into salts and then dissolved in water. In this type of pesticide tea saponin has a wide range of uses, is a promising “environmentally friendly pesticide additives”, welcomed by the majority of users.
As such pesticides are water or soluble powder, so it is on the tea saponin specifications are particularly high, Zhejiang Oriental Tea Industry Science and Technology Co. This is the last decade of tea saponin industrial production technology, a major step forward. Tea Saponin applied to such pesticides is the outstanding advantage that it can improve the physical properties of pesticides, improve the liquid in the target organisms or plant surface adhesion, improve the effectiveness of pesticide use, because Tea Saponin is a natural product that can automatically degrade, non-toxic, harmless, and conducive to environmental protection. In addition, tea saponin separation process, the end product does not contain harmful metals, will not have an impact on the chemical quality of pesticides, pesticide storage is conducive. These advantages are other additives can not be compared.
Take the herbicide glyphosate [N-(phosphine carboxymethyl) glycine] and insecticide bis (2-dimethylamino-1,3-bis(sodium thiosulfonate) propane) as an example, according to Wang Xiaoyi’s research [11-12], tea saponin has a more obvious reduction of the surface tension of the above two pesticide aqueous solutions; the liquid in the surface contact of the plant has a greater impact; and at the same time, improve the amount of liquid deposited in the leaves of the plant.
- Application as biopesticides
The direct application of tea saponins as biopesticides is one of the directional issues that the laboratory led by the author has been engaged in researching for many years. And it has been successful in a number of target animals, Zhu Quanfen had published five consecutive reports [13-17] on the results of research in this area, discussing in detail the mechanism of action and the operation of practical application. Liu Rongxiang and Xia Chunhua reviewed the biological activities of tea saponins. The theorisation of this research has become more complete and mature, and has laid a solid foundation for the application of tea saponin in aquaculture in the past decade. The author in 1995 with the State Science and Technology Commission delegation visited some users in Southeast Asia, the product was unanimously praised and welcomed. This is the reason why in recent years a large number of tea seed cake meal and tea saponin exports from China.
3.1 Tea Saponin in aquaculture applications
Tea Saponin fish toxicity has been applied to aquaculture for fish ponds and shrimp ponds clearing agent, to remove the enemy fish therein. Tea Saponin not only can be used as a pond cleaner before aquaculture, but also can be used in the process of aquaculture to kill the enemy fish. The application of hundreds of hectares of shrimp ponds along the coastline of the three major seas of the East China Sea, Yellow Sea and Bohai Sea have achieved good results [18-19].
Tea saponin is more toxic to fish, even when the concentration is very dilute, the same toxicity, Yamada et al. to robust dingbats as a material, the three Camellia sinensis saponins of tea, camellia and camellia, fish toxicity test, camellia japonica saponin fish toxicity activity is the highest, camellia japonica saponin is the lowest, tea saponin is in the middle. Their LD50 is: tea plum saponin 0.25 mg / L, Camellia sinensis saponin 4.5 mg / L, tea saponin 3.8 mg / L. The salinity of the water quality can promote the tea saponin ichthyotoxic activity, reflecting the tea saponin in freshwater fish on the lethal concentration of tea saponin is higher (about 5 mg / L), on the lethal concentration of saltwater fish is generally less than 1 mg / L. The same concentration of the tea saponin, due to osmolality factors, in the 4‰-10‰ salinity range, the fish death rate is slow, and below or above this concentration area, the death is faster, and its trend is a parabola. In addition, the ichthyotoxic activity of the tea saponins increased with the increase of water temperature, and thus the death rate of fish toxicity was accelerated when the water temperature was high. Seawater is slightly alkaline, so the tea saponin is naturally degraded and inactive after 48h in seawater, so it will not pollute seawater.
According to research, tea saponin fish poisoning mechanism, one is to destroy the gill tissue, the second is to cause haemolysis, the first is to destroy the gill tissue, and then by the gills into the microvessels, thus causing haemolysis, resulting in fish poisoning death.
Tea Saponin on the same gill breathing shrimp have no such effect, the reason is: shrimp gills is the development of the stratum corneum from the stratum corneum area, the main components of the epidermis is the chitin and protein, and the gill structure and composition is very different; on the other hand, the fish’s blood oxygen-carrying carriers for the haemoglobin, the core of the Fe + +, and its shrimp blood oxygen-carrying carriers for the hemocyanin, the core of the Cu + +. Tea saponin on the maximum dilution of animal red blood cells that hemolytic index to measure the size of its activity, hemolytic to tea plum (Camellia sasanqua) saponin the highest, tea (Camellia sinesis) saponin and Camellia sinensis (Camellia japonica) saponin comparable. Tea plum saponin haemolytic index of 1000000, tea saponin and camellia saponin haemolytic index of 100000.
Tea saponin is only haemolytic to blood erythrocytes (including nucleated fish blood, chicken blood and non-nucleated human blood and other red blood cells), while it has no effect on white blood cells. Therefore, tea saponin has toxic effects on fish, the face of the shrimp non-toxic effects. The mechanism of haemolysis is believed to be the tea saponin caused by cholesterol-containing cell membrane permeability changes caused by the initial destruction of the cell membrane, which led to cytoplasmic extravasation, and ultimately disintegrate the entire erythrocyte.
Haemolysis occurs on the premise that tea saponin must be in contact with the blood, and is therefore non-toxic when taken orally in human savings.
3.2 Application of tea saponin as insecticide
Early literature records, tea seed cake can be used as a “soil pesticide” to prevent aphids, borers, lice, leaf mites, wheat leaf rust and stripe rust and so on. In recent years, it has been found that tea saponin has a better killing effect on the low-grade larvae of cabbage butterfly. 25% tea saponin TS-D 500 times water solution, indoor corrective control effect of 83.9%; field corrective control effect of 74% [20]. Tea saponin has a certain gastric toxicity and strong avoidance effect on cabbage greenfly, and the higher the concentration, the stronger the avoidance effect. At the same time, it also has a certain effect on the prevention and control of cabbage damage by cabbage greenfly (Huang Jizhen, 1993). It has also been suggested that the main effect of tea saponin on cabbage greenfly is food refusal [21-22]. It was further observed that tea saponin had a strong effect on the larvae of Phosphoptera, such as cabbage butterflies, cabbage moths, and oblique nightshade moths, in terms of refusal to feed and inhibition of growth and development. Pupation was delayed due to the inhibition of growth and development of cabbage beetles that had fed on tea saponin. Tea saponin has a strong leaching effect on 3rd instar larvae of houseflies, with an LD50 of about 7.5 mg/L. It also has some effect on their pupation rate, but not much on their plumage rate [23].
The control of subterranean pests by tea saponins has been developed only in recent years. Due to the rise of greenhouse agriculture and pollution-free agriculture, underground pests such as tigers, nematodes, earthworms and so on have also become a disastrous and prominent problem. There has been production practice has proved that the use of tea saponin to prevent underground pests effective, and effective, but there is no specific experimental report, only similar to the earth pesticide aspects of the experience.
3.3 Tea Saponin in the extermination of snails and molluscs in the application of killing
In the past, due to the disaster caused by the snail is mainly nail snail, the state has special funds every year for the work of haematological prevention. However, in recent years in the south of China for the introduction of the Fusiliers snail, causing harm, in Guangdong, Taiwan, some areas have occurred, it is said to be more serious. It not only harms crops, but even clogs sewers and reproduces especially fast. Many of the foreign businessmen received by the authors in the past few years were specialised in exploring this matter.
Now there are data to prove [24], tea saponin on the harm of rice Fukushou snail, on the harm of vegetables of the fine drill snail and amber snail (Lv Peike, 1996), on the harm of vegetables of the snail and slugs (Park Lixin, et al. 1993 Xibin 1998), and other harmful snails have a good effect of poisoning. In practice, there are examples of successful application.
Tea saponin has a killing effect on snails. Nail snail is the intermediate host of schistosomiasis, the elimination of nail snail is an important measure to prevent schistosomiasis. The authors have collaborated with the Hunan Blood Control Institute, with tea saponin on the adult snail, young snails and snail eggs for dipping and spraying test, the results show that [25], tea saponin dipping adult snails, young snails and snail eggs have a better killing effect, 5mg/L dipping effect of 100%, the higher the water temperature, the better the killing effect. Tea Saponin also has the same effect.
Tea Saponin kill earthworms with Japanese patents. Mainly used for golf course lawn protection, invented the “Tea Saponin earthworm manure pile prevention agent”. It is said that tea saponin can be used alone as a preventive agent against earthworm faeces, or it can be used in combination with other insecticides. Tea Saponin is used alone at a concentration of 500-1200 times dilution, and evenly sprinkled on the lawn. Test observations, 2 grams of tea saponin dissolved in 2 litres of water (1,000 times), sprinkled on the golf lawn 1 square metres of soil with 67 earthworm dung heaps, sprinkled and observed for 7 days, there is no dung heap formation.
3.4 Application of tea saponin as fungicide
Tea saponin was used in the 1950s to prevent rice blast and blight in rice, with certain control effects. Now research has proved [26] tea saponin in 100mg / L-200mg / L concentration of silk blight has a strong inhibitory effect, three days on the growth of its filamentous fungi inhibition rate of 89.71% and 95.88%, on the white silk disease and rice blight bacteria also have a certain inhibitory effect. More studies have proved that Camellidin I and II, antimicrobial saponins of Camellia sinensis, have the effect of inhibiting the germination of the conidia of tea anthracnose or Verticillium, and also make the spores of rice blast fungus, rice houmous blotch, citrus blackspot fungus, grey mould of tea, tea blight fungus, apple shifting cultivar fungus, pear blackspot fungus, etc., to produce abnormal germination [27]. The phenomenon of tea saponin on plant disease attack Yasuo Ando et al. found that tea saponin had no inhibitory effect on conidial germination of tea anthracnose. Camellia leaf saponin as a biopesticide has been reported in patents [28]. Oil tea saponins also play a special role in oil tea against anthrax [29].
Tea saponins have also been reported in anti-animal pathogens and are of considerable significance for the development of veterinary antimicrobial drugs. The antimicrobial effect of tea saponins has been reflected in the application of tea seed cake as a control of certain skin diseases. Xiong Wenshu found that tea saponin has an inhibitory effect on Candida albicans and Escherichia coli [30]. Jin Jishu et al.’s study on the antimicrobial components of oil tea cake showed that oil tea saponin, which is structurally similar to tea saponin, was proved to have strong antimicrobial activity in both in vitro and clinical pre-tests, with MICs of 0.125-1.000 mg/ml against Trichophyton rubrum gypsophila, Serratia brevetica, Serratia yellows, Serratia violeta, and Serratia floccosus epidermidis, and the strongest antimicrobial activity against Candida albicans, with MICs of 0.0625-0.2500 mg/ml.Clinical trial of 20 cases of dermatophytosis, achieved high efficacy, the cure rate of 75%, the effective rate of 100%.
- Conclusion
(1) Tea Saponin can significantly reduce the surface tension of the liquid, in the concentration of 0.001%-1.0% of the range of surface tension from 76mN/m to 46mN/m. CMC in about 0.5%. In the range of water hardness of 0-28.7od, its surface activity is basically unaffected. At the same time, it has a significant wetting effect on hydrophobic solid surfaces, and its contact angle θ is 0o<θ<90o at a concentration of 1%, with good wetting properties. This is the theoretical basis for the application of tea saponin in the pesticide industry.
(2) Tea Saponin as a wettable pesticide wetting agent; as a polar solvent soluble pesticides in the co-solvent, are with a unique effect. It can make both wettable powder pesticides with good wetting performance. And can make the suspension rate of pesticides to improve, to meet or exceed the national standards, a multi-purpose. Tea Saponin as a soluble powder or water-based pesticide additives more superiority, it does not contain metal ions detrimental to the quality of pesticides, its pH neutral acid, favourable to the storage of pesticides.
(3) Tea Saponin in emulsifiable concentrate pesticides can improve the physical and chemical properties of pesticides. It has the advantages of low dosage, good control effect, fast knockdown speed, resistance to rainfall, efficacy for a long time. Because of the surface activity of tea saponin, it can reduce the amount of pesticides 50% -70%, synergistic effect is obvious, thus conducive to environmental protection.
(4) the use of tea saponin biological activity, the development of biopesticides have broad prospects. Has been developed and successfully developed and applied in practice in aquaculture pond clearing agent, shrimp farming protective agent, crab farming shelling agent, crop and vegetable farming snail, pesticides and so on. Tea Saponin antibacterial, antibacterial effect is expected to be used for storage, poultry farming, in the green livestock products will have a certain future and market.
(5) extract tea saponin resources in our country is extremely rich, the total amount of such resources about 750,000 tonnes. Development of such resources, for the prosperity of mountainous areas of the economy, environmental protection and the development of organic agriculture. All have considerable significance.