Acaricide is a kind of pesticide widely used in the industry, mainly to control mites on crops and ticks on livestock or pets. Every year, the global losses caused by mites are huge. According to the data of the Food and Agriculture Organization of the United Nations, 80% of the world’s cattle are infested by ticks, resulting in a global economic loss of about 7.3 billion USD per year. In South America, the yield loss of soybean plants damaged by the mites Mononyhellus planki McGregor (Acari: Tetranychidae) is about 18.28%[1]. In China, nearly 40 million Mu (1ha=15Mu) of Citrus have also been affected by Panonychus citri (McGregor). Therefore, the global market demand for acaricide is increasing year by year. The top 8 products in the acaricide market in 2018 are: Spirodiclofen, Spiromesifen, Diafenthiuron, Bifenazate, Pyridaben, Propargite, Hexythiazox and Fenpyroximate. Their total sales volume is 572 million USD, accounting for 69.1% of the acaricide market. It is expected that the market size will reach 2 billion USD by 2025. With the reduction of global cultivated land, the increase of population, the increase of demand for natural products and the increase of demand for sustainable agricultural practice, the market size of acaricide may be larger [2].
The analysis of the global acaricide market shows that species of mites, Tetranychidae, Panonychus citri Mc Gregor and Ulmi Panonychus are by far the most important species on agriculture, accounting for more than 80% of the market. Other relevant mite groups are false spider mites (mainly Brevipalpus), rust and gall mites and tarsonemid mites Vegetables and fruits including citrus, grapevine, soybean, cotton and corn (accounting for 74% of the market) are the main crops used for acaricide [3]. Fipronil 5sc
Due to the characteristics of short life cycle, parthenogenesis, unique metabolic tools and strong environmental adaptability of Tetranychidae and Panonychus, their resistance to acaricide has increased rapidly. It is reported that mites account for 3 of the 12 arthropods with pesticide resistant. In the global application of acaricides, conventional chemical acaricides such as organophosphates, carbamates, organochlorine and pyrethroids still occupy a leading position. In recent years, in addition to Bifenazate, Triadimefon and other efficient acaricides have come out. The homogenization of acaricide is still serious, and the phenomenon of rushing to register products that have passed the patent protection period has not changed.
With the long-term and unscientific use of these acaricides, most herbivorous mites have different degrees of resistance to these chemical acaricides on the market, and the effect has decreased significantly. However, with the increasing attention to environmental issues and the gradual increase of the area of organic agriculture, the demand for natural products to protect crops in the global market has increased significantly. Therefore, it is urgent to develop a new type of biological acaricide that is safe, efficient, environmentally friendly, less harmful to natural enemies and not easy to cause pesticide resistance.
Based on this, it is an urgent need for agriculture and industrial development to make full use of China’s biological resource advantages and promote the research, development and application of bio-acaricide. Chengdu Newsun Crop Science Co., Ltd. (Chengdu Newsun) from China, based on the innovative research and development of the efficient co-extraction technology of Veratrum, a Chinese herbal medicine, has developed the acaricide “CE Veratrum Rhizome Extract 0.1% SL “, which can effectively control herbivorous mites.
1. Research Background of Veratrum Alkaloids Veratrum nigrum L., also known as Mountain Onion and Black Veratrum, is a perennial medicinal material. According to Chinese medical records, its roots and rhizomes are used as medicine, which can induce vomiting and expectorant, and mainly treat stroke, phlegm retention, epilepsy, throat obstruction, etc. For external use, it can cure scabies and acne.
Studies on the insecticidal effect of Veratrum have been reported for a long time. As a native insecticidal plant in China, people often dig out its roots during the vegetation period and fry them into a mild soup to cold wash sheep, goats, cattle and other livestock to deal with parasites such as houseflies and maggots [6]. Researchers successively found that Veratrum also had a good control effect on other pests. For example, the ethyl acetate extract from the rhizome of Veratrum has good insecticidal activity against the second and third instar larvae of plutella xylostella, which with dosage 225ppm and 335ppm respectively [7]. The Veratrum alkaloid extract has a certain lethal effect on the adults and fourth instar larvae of blattella germanica [8]. Researchers also found that different extracts from the rhizome of Veratrum have good acaricidal activity, among which ethanol extract > chloroform extract > n-butanol extract [9]. The above research has brought a good reference for the development of the insecticidal and acaricidal functions of Veratrum. However, how to efficiently extract active substances from Veratrum has hindered the industrialization of Veratrum.
Chinese researchers usually use ammonia alkalization chloroform ultrasonic extraction, water extraction, ethanol percolation extraction, supercritical CO2 extraction and other methods to obtain active substances from the rhizome of Veratrum. Among them, the extraction rate of ammonia alkalization chloroform ultrasonic extraction method is relatively high, but uses a large number of toxic solvents chloroform. The ethanol percolation extraction method consumes a large amount of ethanol, and the extraction rate is low. The extraction of veratrum alkaloids by supercritical CO2 extraction method not only has high extraction rate and no damage to the effective components, but also greatly improves the activity and purity of the effective components of the obtained products. In addition, CO2 is non-toxic and solvent-free residue, which is harmless to human and the environment, and can slow down the environmental pollution caused by traditional extraction methods. It has been listed as one of the best extraction and separation technologies for plant efficacy. However, the high-risk production process and high cost hinder its large-scale industrial application.
2. Research And Development Status Of Veratrum Alkaloids 1) Study on Extraction Technology of Veratrum After years of research and development accumulation, Chengdu Newsun first proposed the research ideas and methods of recipe Co-Extraction Technology. Through the unique Co-Extraction Technology, the active substances in the rhizome of Veratrum are greatly excavated to promote the extraction of a variety of active and beneficial ingredients. This technical achievement was registered as Veratrum Rhizome Extract 0.1% SL approved by the Ministry of Agriculture and Rural Affairs of the People’s Republic of China in 2021.
The Co-Extraction Technology takes the Chinese herbal medicine Veratrum as the main raw material and other natural medicinal materials as auxiliary raw materials. Through the process technologies of mixing, crushing, screening, reflux heating, filtration, clarification, concentration and so on, the multiple active components existing in natural substances such as veratramine, resveratrol, veratrosine and so on are prepared together. At the same time, different solvents are used for continuous extraction of plant herbal medicine to maximize the purification and precipitation of the effective active component groups in plant herbal medicines in stages. Finally, obtain groups of compounds with different or similar functions from the same batch of raw materials. This can significantly improve the utilization rate of plant medicinal materials, reduce production costs, and significantly increase market competitiveness.
2) Study on The Mechanism of The Active Substances of Veratrum Veratrum Rhizome Extract is a kind of mixture, which contains more than ten kinds of active ingredients, such asveratramine, resveratrol, veratrosinel and cyclopamine, jervine, oxidized resveratrol, and mainly acts on the nervous system of mites.
According to the research report, its toxicity is based on opening the voltage dependent Na+ channel, and then opening the voltage activated Ca2+ channel, resulting in the release of neurotransmitters. Voltage gated sodium channels are a component of neuronal and muscle signal transduction. The active components in Veratrum extract can cause sodium channel current disorder, lead to membrane permeability changes, cause mites tremor shock, and finally die.
Fig. 1: Observation On The Efficacy of CE Veratrum Rhizome Extract Against Panonychus citri Mc Gregor Under Microscope
At the same time, French researcher reported that veratrum alkaloids can also have non competitive inhibition with mites acetylcholinesterase (AChE) [10]. Because the mechanism of action of veratrum alkaloids is novel and can produce multi-point attack, it is difficult for mites to adapt with multiple action sites through their own structural changes, so it is not easy to cause pesticide resistance.
3) Formulation Technology of CE Veratrum Rhizome Extract 0.1% SL Supported by advanced Co-Extraction Technology, supplemented by excellent formulation technology, the product CE Veratrum Rhizome Extract 0.1% SL has small surface tension, can quickly wrap the insect body, promote the penetration and absorption of the product solution, and enhance the effect of active ingredients. The dispersibility into water is good, and the solution is transparent and homogeneous after dispersion. 1000 times dilution, completely wetting the canvas sheet for 44 seconds, which can quickly wet and penetrate. The multiple light scattering stability data showed that CE Veratrum Rhizome Extract 0.1% SL has good stability and fully meets various field application environments.
Fig. 2: Interface Contact Angle and Surface Tension Data of CE Veratrum Rhizome Extract 0.1% SL
3. Application Technology Research Status of CE Veratrum Rhizome Extract 0.1% SL The unique Co-Extraction Technology has greatly improved the quick effect of the CE Veratrum Rhizome Extract 0.1% SL. Compared with the previous technology, the product of Chengdu Newsun has reduced the use of a single ingredient. And through the unique production process, the ingredients in the product are more and the synergistic effect is more obvious.
Shown in the chart above, CE Veratrum Rhizome Extract 0.1% SL was used to control papaya mites in Sanya, Hainan Province, China, when the total number of papaya mites was 50 on one leaf in average, the efficacy was observed with 20 minutes after applied alone, the efficacy reached 99.1% after 1 day. And the decline rate of total number of papaya mites could still be maintained as 92.9% after 7 days, which was very effective.
At the same time, when use CE Veratrum Rhizome Extract 0.1% SL together with chemical acaricides by tank mixing, it can significantly reduce the total number of mites, reduce the using amount of chemical acaricides and enhance the efficacy, and has very good synergistic effect controlling the mites that with serious pesticide resistance. From above, in the high incidence period of Panonychus citri McGregor in Hezhou, Guangxi, China, it takes 20 minutes to see the effect after spraying CE Veratrum Rhizome Extract 0.1% SL + 30% Etoxazole by tank mixing, and no live mites were found 3 days after the treatment, and the effect could be maintained at more than 95% after 11 days since the treatment. At the early occurrence of Panonychus citri Mc Gregor on orange in Ruijin, Jiangxi Province, no live mites were found after 1 day applied CE Veratrum Rhizome Extract 0.1% SL + 30% Clofentezine. Bifenazate, and no live mites were observed 3 days after application, and the efficacy was about 99% after 16 days.
Treatment No.1: CE Veratrum Rhizome Extract 0.1% SL 1000 X + 40% Bifenazate.Etoxazole 3000X Treatment No.: 2: 40% Bifenazate.Etoxazole 4000X Fig. 3: Efficacy of CE Veratrum Rhizome Extract 0.1% SL Tank Mixing With Bifenazate.Etoxazole Against mites on Orange
Shown in the chart above, using CE Veratrum Rhizome Extract 0.1% SL 1000 dilution times and Bifenazate.Etoxazole to control the mites in orange orchard (with an average of more than 80 red spiders per shoot) in Ningdu County, Ganzhou City, Jiangxi Province, China, we see the efficacy of product Bifenazate.Etoxazole is not very well when use it alone, only 82.68% after 1 day, and decreased to 65.03% after 7 days. However, when using amount of product Bifenazate.Etoxazole was reduced by 25% and tank mixing with CE Veratrum Rizome Extract 0.1% SL, the efficacy was 94.72% after 1 day, and still with 82.68 after 7 days. This is not only improved the quick effect, but also significantly enhance the effectiveness and reduce the using amount of chemical acaricide products..
In the area of Panonychus citri McGregor with pesticide resistance, the efficacy of “CE Veratrum Rhizome Extract 0.1% SL + chemical acaricides” is also excellent. From the above, in the case of a large total number of mites (high incidence period) in Wuming, Nanning, Guangxi, China (before treatment, there were at least 35 mites average on each leaf), the decline rate of total number of mites by applying CE Veratrum Rhizome Extract 0.1% SL together with Abamectin. Etoxazole, Fenbutatin Oxide, Propargite and mineral oil by tank mixing is all more than 98% after 1 day and 3 days. The decline rate of total number of mites was still more than 99% after 8 days, only except using CE Veratrum Rhizome Extract 0.1% SL + Propargite, there is a small number of eggs hatched, and its decline rate of total number of mites was 92.33%.
The above field bioassay results showed that when the total number of mites is small or big, using alone or using together with chemical acaricides, Veratrum Rhizome Extract had shown excellent effects in reducing total number of mites and enhancing the effect of chemical acaricides. At the same time, Veratrum Rhizome Extract comes from plants. At the recommended dilution times, it is safe to apply it to most plants at the germination stage, flowering stage, young fruit stage and other stages, and has no affect on buds, flowers and fruit enlargement. It is safe to non target organisms such as natural enemies of mites, friendly to the environment, and has no cross resistance to existing insecticides and acaricides. It is very suitable for the comprehensive management of harmful mites (IPM). With the reduction of the use of chemical acaricides, the residues of chemical pesticides in citrus, such as Ethiconazole, Spirodirin, Bifenazate and so on, can fully meet 《The Maximum Residue Limit Of Pesticides In Food Of The National Food Safety Standard Of China》, 《The Maximum Residue Limit Of Pesticides In Food Of The European Union》 and 《The Maximum Residue Limit Of Pesticides In Food Of The United States》, providing a solid guarantee for food safety and the quality and safety of agricultural products.
4. Gene Editing Technology Promotes the Industrialization of Veratrum Veratrum is a common medicinal material. It is a perennial herb of Veratrum L. in Liliaceae. It grows in mountains, forests or shrubs, mainly distributed in Shanxi Province, Hebei Province, Henan Province, Shandong Province, Liaoning Province, Sichuan Province, Jiangsu Province and other places in China, and rich in wild resources. According to the investigation, the annual output of medicinal Veratrum is close to 300-500 tons, and the varieties include Veratrum Maoye, Veratrum Xing’an, Veratrum Maosui, Veratrum Guling and other varieties. The active components of each variety are different.
With the rapid development of biotechnology and the in-depth study of Veratrum, the use of Gene Editing Technology to improve Veratrum varieties and the artificial domestication of wild Veratrum varieties have made phased progress. Artificial cultivation of Veratrum varieties will greatly reduce the damage of Veratrum mining to wild germplasm resources, and further promote the industrialization of Veratrum in agriculture and medicine.
The research and development of Veratrum Rhizome Extract took nearly 10 years. Chengdu Newsun searched for effective substances that can control Panonychus citri McGregor from plants, matched unique Co-Extraction Technology, and authorized a number of National Patents. These increased the efficacy of Veratrum Rhizome Extract several times, and successfully realized the industrialization of the market of Biological Acaricide. In the future, natural Veratrum Rhizome Extract from medicinal plants is expected to gradually reduce the using amount of traditional chemical acaricides, and will make greater contributions to improve the quality of agricultural products, improve the safety of agricultural products, improve the agricultural ecological environment and maintaining biodiversity.
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