Cassava leaf extract as well as preparation method and application thereof in prevention and treatment of tetranychus cinnabarinus
By preparing cassava leaf extract for pesticide production, the problem of high resistance of Tetranychus carmine to chemical acaricides has been solved, achieving highly effective control and environmentally friendly pesticide application, utilizing agricultural waste resources, and reducing costs.
Patent Information
- Application Number
- CN202511168861.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-20
- Publication Date
- 2025-12-26
AI Technical Summary
The Tetranychus cinnabarinus faces challenges such as high resistance to mainstream chemical acaricides, poor control efficacy, environmental pollution, insufficient activity of traditional plant-derived pesticides, and high raw material costs.
Cassava leaf extract was prepared by adding extraction solvent and biological enzymes, and the extract was dried to obtain cassava leaf extract. This extract was used to prepare a pesticide for controlling spider mites and was applied to the surface of crops by spraying.
It achieves highly efficient control of carmine spider mites, avoids pest resistance, is environmentally friendly, has a wide range of raw material sources, is low in cost, and meets the requirements of green development in modern agriculture.
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Figure CN121195980A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of pesticide technology, specifically to a cassava leaf extract, its preparation method, and its application in controlling the red spider mite. Background Technology
[0002] The carmine spider mite (Tetranychus cinnabarinus), also known as the red spider mite, is a globally distributed agricultural pest with a wide host range, damaging crops such as cassava, eggplant, beans, melons, tomatoes, peppers, and black nightshade, as well as weeds. Adults and nymphs feed on sap on the undersides of leaves, causing chlorosis, curling, drying, and even plant death, severely impacting crop yield and quality. The carmine spider mite can tolerate a wide range of temperature variations but prefers hot, dry environments. With climate change and altered planting structures, as a non-target pest, the occurrence of the carmine spider mite has increased year by year, causing cassava yield reductions of 30% to 70%, or even total crop failure, making it a dominant pest of cassava.
[0003] Currently, the control of Tetranychus carmine mainly relies on chemical acaricides (such as abamectin and pyrethroids), but long-term use can easily lead to drug resistance, environmental pollution, and food safety issues. Therefore, the development of highly effective and low-toxicity plant-derived acaricides has become a research hotspot. Plant-derived pesticides have advantages such as being environmentally friendly, having diverse modes of action, being less likely to induce resistance, having relatively mild effects, and having abundant raw materials, giving them a very broad development prospect. For example, in recent years, there has been much research on plant-derived insecticides, and extracts from plants such as lavender and lemongrass have been proven to have acaricidal activity. The development of plant-derived pesticides has become one of the research hotspots both domestically and internationally.
[0004] Secondary metabolites produced by plants possess specific biological activities and can serve as excellent alternatives to synthetic organic pesticides, acting as natural insecticides. Unlike primary metabolites, secondary metabolites produced by plants during cellular activities (such as phenolic compounds, tannins, coumarins, flavonoids, and alkaloids) play a more significant role in combating mites, affecting the normal feeding, reproduction, growth, development, and oviposition of pests, and even poisoning them. For example, phenolic compounds produced by plants inhibit the growth, survival, development, and reproduction of pests. Phenolic secondary metabolites entering the digestive system of pests can cause oxidative damage, thus exerting a toxic effect. Tannins can bind to proteins and digestive enzymes in the intestines of weevil larvae, causing the weevils to die. Phenolic compounds can also reduce the crop preference of pests. Studies have shown that polar phenolic compounds in wheat have strong deterrent activity against green peach aphids and wheat aphids. Flavonoids are important secondary metabolites in plants, playing a crucial role in plant resistance to insect pest stress. Studies have found that flavonoids in plants, such as catechins, kaempferol, and rutin, can significantly alter the feeding habits and oviposition behaviors of pests, thus affecting their survival. Exogenous supplementation with flavonoids also greatly influences insect growth and development. For example, under feeding treatments with high concentrations of quercetin and chlorogenic acid, the mortality rates of the fall webworm reached 70.00% and 67.50%, respectively.
[0005] Cassava leaves are rich in various nutrients and bioactive compounds, such as vitamins, minerals, proteins, flavonoids, and phenolic compounds. Previous studies have shown that, compared with susceptible varieties, resistant varieties have higher contents of total flavonoids, total phenols, and tannins, and the contents of total flavonoids, total phenols, and tannins increase significantly after infestation. Cassava mite resistance is positively correlated with the contents of tannins and total flavonoids, indicating that these metabolites may play a key role in cassava's defense against Tetranychus carinata (Wei Wanling. Study on resistance of different cassava varieties (lines) to Tetranychus carinata [D]. Guangxi University, 2018. Wei Wanling, Luo Xinglu, Pan Xiaolu, et al. Relationship between resistance of different cassava varieties to Tetranychus carinata and their leaf contents [J]. Journal of China Agricultural University, 2020, 25(05):13-21. Wei Wanling, He Wen, Ruan Lixia, et al. Physiological response of diploid and its homotetraploid of South China 205 cassava to Tetranychus carinata feeding stress [J]. Journal of Plant Protection, 2024, 51(02):456-466.). However, there are few reports on the activity of flavonoids from cassava leaves against the spider mite *Tetranychus carinata*. Cassava leaves are abundant, readily available, and inexpensive, making the development of highly effective biological acaricides based on cassava leaf extracts a promising new strategy for green agricultural pest control. Therefore, this invention provides a cassava leaf extract, its preparation method, and its application in controlling *Tetranychus carinata*. Summary of the Invention
[0006] The technical problem to be solved by this invention is to provide a cassava leaf extract, its preparation method, and its application in the control of Tetranychus carmine. The aim is to address the problems of Tetranychus carmine, such as high resistance to mainstream chemical acaricides, poor control efficacy, environmental pollution, and the insufficient activity and high raw material costs of traditional plant-derived pesticides.
[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, a method for preparing a cassava leaf extract includes the following steps: adding an extraction solvent and a biological enzyme to cassava leaves to extract an infusion solution; and drying the infusion solution to obtain the cassava leaf extract.
[0008] Based on the above technical solution, the present invention can be further improved as follows.
[0009] Furthermore, the ratio of the cassava leaves to the extraction solvent is 1 kg: 15~30 L; The extraction solvent includes an organic solvent and water, wherein the volume content of the organic solvent in the extraction solvent is 40% to 90%. The bioenzyme includes at least one of cellulase, pectinase, hemicellulase or papain. The bioenzymes comprise 0.3% to 2.0% of the mass of the cassava leaves. Specifically, based on the dry weight of the cassava leaves, the cellulase comprises 0.5% to 1.2% of the mass of the cassava leaves; the pectinase comprises 0.3% to 1.0% of the mass of the cassava leaves; the hemicellulase comprises 0.3% to 1.0% of the mass of the cassava leaves; and the papain comprises 0.6% to 2.0% of the mass of the cassava leaves.
[0010] Furthermore, the organic solvent includes at least one of methanol, ethanol, and acetone.
[0011] Furthermore, the specific steps include the following: Extraction solvent and bio-enzyme are added to cassava leaves, and ultrasonic extraction is performed. The soaking liquid is collected by filtration. The extraction solvent is added to the filtered residue again, and ultrasonic extraction is performed again. The soaking liquid is collected by filtration again. All the collected soaking liquids are concentrated and dried under vacuum to obtain cassava leaf extract.
[0012] Furthermore, the conditions for ultrasound-assisted extraction are: power 200W~400W, time 30 min~90 min; The conditions for ultrasound-assisted re-extraction are: 200W~400W, time 20 min~60 min; The conditions for vacuum concentration and drying are: temperature 55±5℃, vacuum degree 0.05MPa~0.10MPa.
[0013] Secondly, a cassava leaf extract, which is prepared by the method described above.
[0014] Thirdly, the application of a cassava leaf extract, wherein the cassava leaf extract is used in the preparation of a pesticide to control the spider mite.
[0015] Fourthly, a pesticide for controlling the spider mite, said pesticide comprising the aforementioned cassava leaf extract and emulsifier.
[0016] The method of using this pesticide to control the carmine spider mite is as follows: spray it on the surface of the crop. The plant surface should be moistened.
[0017] Furthermore, the emulsifier includes at least one of sodium dodecyl sulfate (SDS), Tween-60, and Tween-80. The mass concentration of the emulsifier in the pesticide is 1 g / L to 5 g / L.
[0018] Furthermore, the cassava leaf extract in the pesticide contains 1% to 5% by mass.
[0019] The beneficial effects of this invention are: (1) Compared with traditional chemical pesticides, the cassava leaf extract of the present invention has a high control effect through the synergistic effect of a variety of secondary metabolites (flavonoids, phenols, etc.), which can effectively prevent pests from developing resistance and has a longer-lasting control effect.
[0020] (2) This invention uses cassava processing by-products (cassava leaves) as raw materials, which not only realizes the resource utilization of agricultural waste, but also has a wide range of raw material sources, low cost, simple processing technology, and low requirements for production equipment, thus having obvious economic advantages.
[0021] (3) The main components of the cassava leaf extract of the present invention are natural plant metabolites, which are soluble in water and easy to be formulated into an aqueous solution for use. The preparation is environmentally friendly, safe for humans and animals, and belongs to environmentally friendly and pollution-free biological acaricides, which meet the requirements of green development in modern agriculture. Attached Figure Description
[0022] Figure 1 The image shows the acaricidal effect of spraying cassava leaf extract (left) and abamectin emulsifiable concentrate (right) according to the present invention. Figure 2 This is a diagram showing the initial mite population on cassava leaves before spraying the cassava leaf extract according to this invention. Figure 3 This is a 3D effect diagram of the application of cassava leaf extract according to the present invention. Detailed Implementation
[0023] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.
[0024] Description of the source of materials and reagents: Cassava leaves were collected from the cassava resource nursery of the Guangxi Subtropical Agricultural Research Institute. Cassava varieties such as South China No. 5 and South China No. 9, which are resistant to mites at a medium or higher level, were used as samples. Mature leaves from the middle and lower parts of plants that were more than 60 days after planting were used as samples. The samples were dried, crushed and passed through a 40-mesh sieve for later use.
[0025] The carmine spider mite was derived from an experimental population subcultured indoors using cowpeas. The rearing conditions were: temperature (26±2)℃, relative humidity (75±5)%, and photoperiod 14 (L):10 (D). Adult mites with similar developmental stages and sizes were selected for subsequent experiments.
[0026] Bioenzymes: cellulase, pectinase, hemicellulase, and papain, Nanning Dongheng Huadao Biotechnology Co., Ltd.; Sodium dodecyl sulfate (SDS) was a domestically produced analytical grade reagent; Tween-60 and Tween-80 were from Haian Xinhuihan Chemical Co., Ltd.; Avermectin emulsifiable concentrate was from Shandong Lukang Biological Pesticide Co., Ltd.
[0027] Example 1. Preparation of cassava leaf extract.
[0028] This embodiment relates to a cassava leaf extract and its preparation method, comprising the following steps: adding an extraction solvent and a biological enzyme to dried cassava leaves to extract an infusion solution; drying the infusion solution to obtain the cassava leaf extract.
[0029] Preferably, in this embodiment, the ratio of dried cassava leaves to the extraction solvent is 1:15~30 (kg / L); the volume content of organic solvent in the extraction solvent is 40%~90%; the bioenzyme includes at least one of cellulase, pectinase, hemicellulase or papain. The bioenzymes comprise 0.3% to 2.0% of the mass of the cassava leaves. Specifically, based on the dry weight of the cassava leaves, the cellulase comprises 0.5% to 1.2% of the mass of the cassava leaves; the pectinase comprises 0.3% to 1.0% of the mass of the cassava leaves; the hemicellulase comprises 0.3% to 1.0% of the mass of the cassava leaves; and the papain comprises 0.6% to 2.0% of the mass of the cassava leaves.
[0030] Preferably, the organic solvent described in this embodiment includes at least one of methanol, ethanol, and acetone.
[0031] Specifically, the cassava leaf extract and its preparation method in this embodiment include the following specific steps: Mature leaves from the lower and middle parts of cassava varieties (such as Huanan No. 5 and Huanan No. 9) that are more than 60 days old after planting and have strong mite resistance were collected. After drying at 40℃, the leaves were pulverized and passed through a 40-mesh sieve. 1 kg of cassava leaf powder was taken and 15 L of 60% ethanol aqueous solution was added, along with 5 g of cellulase (0.5% of the dry weight of the cassava leaves). The mixture was stirred and stirred evenly, and ultrasonic extraction was performed for 30 min (360 W). The filtrate was collected by passing it through a 200-mesh filter or by centrifugation (4000 rpm, 10 min). An appropriate amount of 60% ethanol was added to the leaves again, and the extraction was repeated once more, ultrasonic extraction was performed for 20 min (360 W), and the mixture was filtered. The two filtrates were combined and evaporated to dryness under vacuum of 0.08 MPa and 55℃ to obtain the cassava leaf extract, which was used for subsequent experiments.
[0032] 2. Verification of the bioactivity of cassava leaf extract against Tetranychus cinnabarinus.
[0033] (1) Test subjects: In the laboratory, fresh and clean cowpea leaves were used to raise the mites for more than 3 generations. Female adult mites with the same body size, health and vitality were selected as test subjects.
[0034] (2) Test reagents: Cassava leaf extract was diluted with an aqueous solution of Tween-80 with a mass concentration of 2.5 g / L to prepare preparations with cassava leaf extract concentrations of 1 wt%, 3 wt%, and 5 wt%, with water as a control.
[0035] (3) Test method: immersion method.
[0036] Thirty adult spider mites, subcultured in the laboratory, were inoculated onto fresh cowpea leaflets. The inoculated leaves were immersed in different concentrations of pesticide for 5 seconds, then removed and the excess solution was gently absorbed with filter paper, ensuring the leaf surface remained moist. The immersed leaves were then placed in a small white bottle (20 ml) containing clean water, with each treatment repeated three times. The treated insects were cultured under normal conditions, and their growth was observed regularly. After 24 hours, the number of live and dead insects in each treatment was investigated. Insects that did not move their legs after being lightly touched with the tip of a brush were considered dead. The mortality rate was calculated using formula (1) or corrected using formula (2).
[0037] (1); (2); Note: If the mortality rate of the control group is <5%, no correction is required; if the mortality rate of the control group is between 5% and 20%, it should be corrected according to the corrected mortality rate formula; if the mortality rate of the control group is >20%, the data is unreliable and the experiment needs to be repeated.
[0038] (4) Experimental results: Table 1. Control effects of different concentrations of cassava leaf extract on Tetranychus carmine. Table 1 shows that cassava leaf extract has a certain lethal effect on Tetranychus carinata, and the mortality rate increases with the increase of extract concentration. When the concentration of cassava leaf extract is 5 wt%, the mortality rate of Tetranychus carinata reaches 96.7%, indicating strong acaricidal activity.
[0039] 3. Comparison of the control effects of cassava leaf extract and mainstream acaricides.
[0040] (1) Test crop: cowpea.
[0041] (2) Test subject: Tetranychus cinnabarinus.
[0042] (3) Test methods: Once the cowpeas had grown six fully expanded leaves and reached a height of over 30 cm, they were inoculated with the carmine spider mite. Each cowpea plant was inoculated with 60 laboratory-cultured adult female mites. Three days after inoculation, pesticide treatment was administered. Three pesticide treatments were set up: A) water (control); B) 1.8% abamectin EC at a dilution of 4000 times; C) a pesticide with a 5wt% concentration of cassava leaf extract. The pesticide was sprayed using a sprayer, covering both sides of the leaves until they were moist but not dripping. A carmine spider mite population survey was conducted before treatment, and the number of live mites was surveyed at 1, 3, 7, and 14 days after treatment. The population reduction rate and control effect were calculated.
[0043] (3); (4); In the above formula (4), CK0 and CK1 are the number of live mites before and after application of the drug in the blank control area, respectively, and PT1 and PT2 are the number of live mites before and after application of the drug in the drug-treated area, respectively.
[0044] (4) Experimental results: Table 2. Control efficacy of different pesticides against Tetranychus carmine. Note: Data in the same column marked with * indicates that the two groups of data are significantly different at the P<0.05 level.
[0045] Depend on Figure 1It can be seen that the acaricidal effects of cassava leaf extract and the mainstream acaricide abamectin EC are significantly different. Table 2 shows that one day after application: the insect population reduction rate of cassava leaf extract (5wt%) reached 60.00%, significantly higher than abamectin (49.53%), with a control effect 10.14 percentage points higher, indicating a faster acaricidal effect. Three days after application: the control effect of cassava leaf extract reached 81.48%, an increase of 9.83 percentage points compared to abamectin (71.65%), a significant difference. Seven days after application: the peak acaricidal effect of cassava leaf extract (5wt%) reached 93.27%, further widening the advantage over abamectin (80.61%). At this point, a large number of mites on the leaves died and fell off, and there were basically no live mites on the leaves. Figure 3 Fourteen days after application, the cassava leaf extract maintained a control efficacy of 91.01%, which was 11.65 percentage points higher than that of abamectin (79.36%), and the efficacy did not show a significant decline (only a decrease of 2.26 percentage points compared to 7 days). This indicates that the cassava leaf extract has a significant acaricidal effect against the carmine spider mite and has the potential to be developed into an acaricide.
[0046] In summary, compared with traditional chemical pesticides, the cassava leaf extract of this invention achieves highly efficient control through the synergistic effect of multiple secondary metabolites (flavonoids, phenols, etc.), effectively preventing pests from developing resistance and providing a more lasting control effect. This invention utilizes cassava processing byproducts (cassava leaves) as raw materials, not only realizing the resource utilization of agricultural waste but also offering significant economic advantages due to the wide availability of raw materials, low cost, simple processing technology, and low requirements for production equipment. The main components of the cassava leaf extract of this invention are natural plant metabolites, soluble in water, and easy to formulate into an aqueous solution. This formulation is environmentally friendly, safe for humans and animals, and is a non-polluting biological acaricide, meeting the requirements of modern green agricultural development.
[0047] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method of preparing cassava leaf extract, characterized in that, The method comprises the following steps: adding an extraction solvent and a biological enzyme into cassava leaves to obtain a soaking solution by extraction; and drying the soaking solution to obtain a cassava leaf extract.
2. The process for the preparation of cassava leaf extract as claimed in claim 1, wherein, The ratio of the cassava leaves to the extraction solvent is 1 kg: 15-30 L. The extraction solvent comprises an organic solvent and water, and the volume content of the organic solvent in the extraction solvent is 40-90%. The biological enzyme comprises at least one of cellulase, pectinase, hemicellulase and papain. The biological enzyme accounts for 0.3-2.0% of the mass of the cassava leaves.
3. The process for the preparation of cassava leaf extract as claimed in claim 2, wherein, The organic solvent comprises at least one of methanol, ethanol and acetone.
4. The process for the preparation of cassava leaf extract according to any one of claims 1 to 3, characterized in that, The method comprises the following specific steps: The method comprises the following specific steps: adding an extraction solvent and a biological enzyme into cassava leaves to obtain a soaking solution by ultrasonic-assisted extraction, filtering and collecting the soaking solution, adding the extraction solvent into the filtered residue again, performing ultrasonic-assisted re-extraction, filtering and collecting the soaking solution again, and drying the collected soaking solution by vacuum concentration to obtain a cassava leaf extract.
5. The process for the preparation of cassava leaf extract as claimed in claim 4, wherein, The ultrasonic-assisted extraction is performed at a power of 200-400 W for 30-90 min. The ultrasonic-assisted re-extraction is performed at a power of 200-400 W for 20-60 min. The vacuum concentration is performed at a temperature of 55±5 DEG C and a vacuum degree of 0.05-0.10 MPa.
6. A cassava leaf extract, characterized in that, The cassava leaf extract is prepared by the method of any one of claims 1-5.
7. Use of cassava leaf extract, characterized in that, The cassava leaf extract of claim 6 is used for preparing a pesticide for preventing and treating Tetranychus cinnabarinus.
8. A pesticide for controlling Tetranychus cinnabarinus, characterized by comprising the compound according to any one of claims 1 to 7. The pesticide comprises the cassava leaf extract of claim 6 and an emulsifier.
9. The pesticide for controlling T. castaneum according to claim 8, characterized in that, The emulsifier comprises at least one of sodium dodecyl sulfate, Tween-60 and Tween-80.
10. The pesticide for controlling T. castaneum according to claim 8, characterized in that, The mass content of the cassava leaf extract in the pesticide is 1-5%. The method comprises the following steps: adding an extraction solvent and a biological enzyme into cassava leaves to obtain a soaking solution by extraction; and drying the soaking solution to obtain a cassava leaf extract. The ratio of the cassava leaves to the extraction solvent is 1 kg: 15-30 L. The extraction solvent comprises an organic solvent and water, and the volume content of the organic solvent in the extraction solvent is 40-90%. The biological enzyme comprises at least one of cellulase, pectinase, hemicellulase and papain. The biological enzyme accounts for 0.3-2.0% of the mass of the cassava leaves. The organic solvent comprises at least one of methanol, ethanol and acetone. The method comprises the following specific steps: The method comprises the following specific steps: adding an extraction solvent and a biological enzyme into cassava leaves to obtain a soaking solution by ultrasonic-assisted extraction, filtering and collecting the soaking solution, adding the extraction solvent into the filtered residue again, performing ultrasonic-assisted re-extraction, filtering and collecting the soaking solution again, and drying the collected soaking solution by vacuum concentration to obtain a cassava leaf extract. The ultrasonic-assisted extraction is performed at a power of 200-400 W for 30-90 min. The ultrasonic-assisted re-extraction is performed at a power of 200-400 W for 20-60 min. The vacuum concentration is performed at a temperature of 55±5 DEG C and a vacuum degree of 0.05-0.10 MPa. The cassava leaf extract is prepared by the method of any one of claims 1-5. The cassava leaf extract of claim 6 is used for preparing a pesticide for preventing and treating Tetranychus cinnabarinus. The pesticide comprises the cassava leaf extract of claim 6 and an emulsifier. The emulsifier comprises at least one of sodium dodecyl sulfate, Tween-60 and Tween-80. The mass content of the cassava leaf extract in the pesticide is 1-5%.