An azadirachtin oil composition for controlling psylloids and a method for preparing the same

Abstract

The present application relates to the technical field of agricultural preparation, in particular to a kind of neem oil composition for preventing and treating wood lice and its preparation method;A kind of neem oil composition for preventing and treating wood lice, consisting of the following mass percentage components: 12-15% neem oil, 4-6% carvacol, 25-30% water-soluble alkali lignin, 2-4% arginine, 2-5% oligomeric chitosan, 3-6% glycerol, 0.5-2% ascorbyl palmitate and deionized water balance;The present application systematically solves the technical problems of existing neem oil preparation, such as rapid photodegradation, short effective period and poor liquid storage stability, through the ultraviolet shielding and anti-ostwald ripening effect of lignin sodium sulfonate nanocapsule wall material, the quick-acting fumigation of carvacol and neem oil, the long-acting antifeedant synergistic mechanism and the whole-process organic solvent-free nitrogen protection green preparation process, realizing the quick-acting and long-acting prevention and treatment of citrus wood lice, and providing a new solution for the green prevention and control of citrus wood lice, which has excellent storage stability and field persistence.

Description

Technical Field

[0001] This invention relates to the field of agricultural formulation technology, specifically to a neem oil composition for controlling psyllids and its preparation method. Background Technology

[0002] Citrus psyllids are the main vectors of citrus Huanglongbing (HLB), posing a serious threat to the citrus industry. Neem oil, as a natural plant-derived insecticide, has good anti-feeding, repellent, and growth-inhibiting effects on psyllids, and is unlikely to induce resistance. Currently, domestic neem oil preparations exist in the form of emulsifiable concentrates or microemulsions, which contain a large amount of organic solvents, making them unfriendly to the environment and natural enemies. Furthermore, the active ingredient in neem oil, azadirachtin, is extremely sensitive to ultraviolet light, and after field application, it degrades rapidly, with an effective period of only 3-5 days, requiring frequent application, which increases control costs and labor input. Nanoencapsulation of neem oil is an important direction for achieving long-lasting sustained release and UV protection. However, existing lignin-based microcapsule technology uses a solid, dense capsule wall structure, making it difficult to control the release rate of active ingredients, resulting in insufficient rapid effect or unsatisfactory duration of action. Furthermore, during long-term storage, liquid nanocapsule suspensions undergo Ostwald ripening, leading to particle size increase, stratification, and aggregation, making it difficult to guarantee system stability. Therefore, the key to overcoming the technological barriers of green control of citrus psyllids lies in constructing a neem oil nanodelivery system with a capsule wall possessing natural UV shielding capabilities, capable of controllable release of the core material's active ingredients, and stable for long-term storage, all while eliminating the need for organic solvents.

[0003] To address the above problems, the present invention provides a solution. Summary of the Invention

[0004] The purpose of this invention is to provide a neem essential oil composition for controlling psyllids and its preparation method, which can effectively control piercing-sucking pests such as citrus psyllids, and has the advantages of long-lasting UV protection, controllable rapid release and excellent storage stability, while eliminating the use of organic solvents and achieving green and environmentally friendly results.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a neem oil composition for controlling psyllids, comprising the following components by mass percentage: 12-15% neem oil, 4-6% carvacrol, 25-30% water-soluble alkali lignin, 2-4% arginine, 2-5% oligochitosan, 3-6% glycerol, 0.5-2% ascorbyl palmitate, and the balance being deionized water; Furthermore, a method for preparing a neem essential oil composition for controlling psyllids includes the following steps: S1: Add deionized water to a reactor equipped with a jacketed heating system and a high-speed dispersion plate. Turn on the reactor stirrer and set the stirrer speed to 200 rpm. Heat the reactor to 45°C using circulating water in the jacket. After the temperature stabilizes, add water-soluble alkali lignin to the deionized water in batches while stirring. Add each batch 3 minutes apart and add in three batches. After the addition is complete, increase the stirrer speed to 350 rpm and continue stirring for 30 minutes to obtain a dark brown, homogeneous lignin solution. S2: Pass arginine through a 60-mesh sieve. Add the sieved arginine to the lignin solution while stirring. Control the addition time to 10 minutes. After adding, continue stirring for 12 minutes. After standing to defoam, add oligochitosan and glycerol in sequence, with an interval of 5 minutes between each addition. After adding, set the stirring speed to 450 rpm and continue stirring for 15 minutes to obtain the wall material solution. S3: The wall material solution is pumped through a diaphragm pump into a plate filter with a 0.8 μm pore size polytetrafluoroethylene filter membrane for vacuum negative pressure filtration. The vacuum degree is -0.075 MPa. The filtrate is collected in a clean receiving tank to obtain a refined wall material solution. The cooling water in the jacket of the receiving tank is turned on to cool the refined wall material aqueous phase to 25°C for later use. S4: Add neem essential oil to a light-proof treatment vessel equipped with a jacketed heating and reflux condenser. Turn on the stirrer of the treatment vessel and set the speed to 100 rpm. Heat the vessel to 38°C through a jacketed water bath. After the temperature stabilizes, add carvacrol and ascorbyl palmitate in sequence. After the addition is complete, increase the stirrer speed to 150 rpm and stir and mix for 18 minutes under a nitrogen protective atmosphere. Throughout the mixing process, the treatment vessel maintains a nitrogen atmosphere through the reflux condenser. After mixing, let it stand for 5 minutes to obtain a reddish-brown transparent enhanced oil phase. Transfer the enhanced oil phase to a brown reagent bottle that has been pre-purged with nitrogen using a metering pump. After the transfer, purge the bottle with nitrogen again for 30 seconds to purge the air at the bottle opening. Seal immediately and store in the dark for later use. S5: Transfer the refined wall material solution to the emulsification tank of the high-speed shear emulsifier. The emulsifier is equipped with a circulating cooling jacket and a low-temperature constant temperature circulation tank is pre-connected and the circulating liquid temperature is set to 25℃. Circulation is started for 30 minutes to stabilize the temperature of the inner wall of the emulsifier. Add the enhanced oil phase to the constant temperature dropping tank with magnetic stirring. Set the temperature of the constant temperature dropping tank to 25℃ and the stirring speed to 80 rpm. Start the high-speed shear emulsifier and set the shearing speed to 5000 rpm for pre-dispersion. At the same time, turn on the peristaltic pump to slowly inject the enhanced oil phase into the wall material aqueous phase at a constant rate of 1 ml / s through a stainless steel dropping tube with an inner diameter of 2 mm. During the dropping process, the shearing speed is gradually increased to 12000 rpm. After the dropping is completed, maintain the shearing speed at 12000 rpm for 10 minutes. During the shearing process, the emulsion temperature is controlled not to exceed 30℃ by the circulating cooling jacket to obtain a nanocapsule suspension. S6: The nanocapsule suspension was transferred to an aging vessel equipped with an anchor stirrer and a jacketed temperature control via a rotary pump. The stirring speed was set to 120 rpm, and the suspension was aged at room temperature for 45 minutes. During the aging process, 5 ml of sample was taken from the sampling valve every 15 minutes to observe the state of the suspension and confirm that there was no stratification or flocculation. After the aging was completed, an organosilicon defoamer was added to the aging vessel. After the addition, the stirring speed was briefly increased to 200 rpm and stirred for 3 minutes for rapid dispersion. Then, the stirring speed was restored to 120 rpm and stirred for another 5 minutes for defoaming. After defoaming was completed, the suspension was allowed to stand for 10 minutes to obtain the aged nanocapsule suspension. S7: Connect the aged nanocapsule suspension to the feed buffer tank of the filling machine equipped with an 80-mesh stainless steel online filter via a hose. The feed buffer tank is equipped with a low-speed anchor agitator, and the agitation speed is set to 60 rpm to prevent the suspension from settling. Before filling, purge the filling pipeline and filling head with nitrogen for 30 seconds to remove air. Use light-proof HDPE bottles with aluminum foil composite liners as filling containers. Nitrogen gas is used for protection during the filling process. The filling volume is 85% of the bottle's internal volume. Immediately after filling, screw the cap on and seal the bottle. Check the sealing of each bottle and discard those with poor sealing to obtain the neem essential oil composition for controlling psyllids.

[0006] Furthermore, the oligochitosan has a molecular weight ≤3000 Da and a degree of deacetylation ≥90%; the water-soluble alkali lignin is sodium lignin sulfonate, with a lignin content ≥85 wt%, ash content ≤5 wt%, moisture content ≤8 wt%, and a pH value of 8-10 for a 1% aqueous solution; the neem oil is extracted by cold pressing, with an azadirachtin content ≥1500 ppm. Furthermore, the silicone defoamer mentioned in step S6 is a polydimethylsiloxane emulsion type defoamer, and the mass ratio of the silicone defoamer to the nanocapsule suspension is 0.06:100. In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: 1: This invention creates a nano-sustained-release delivery system with sodium lignosulfonate nanocapsule wall material as the core and neem oil and carvacrol as two-component synergistic core materials. Sodium lignosulfonate self-assembles into nanocapsules at the oil-water interface under alkaline conditions through the pH buffering and assembly aiding effect of arginine. The polyphenolic aromatic ring structure of lignin in the capsule wall provides a natural ultraviolet absorption barrier, effectively shielding the degradation effect of ultraviolet light on the core material neem oil. This systematically solves the key problems of rapid photodegradation, short duration of effect, and poor storage stability of liquid formulations in existing neem oil preparations. 2: This invention uses the synergistic combination of neem oil and carvacrol as the core enhancement mechanism to construct a dual control system of rapid fumigation and contact killing and long-term antifeedant inhibition. Carvacrol has strong fumigation and contact killing activity, which can quickly knock down adult citrus psyllids after application. At the same time, the inhibitory effect of carvacrol on the detoxification enzyme system in the psyllid enhances the toxicity of neem oil. After being encapsulated in nanocapsules, neem oil achieves controlled and slow release, continuously exerting antifeedant, repellent and growth-inhibiting effects, thus balancing the contradictory needs of rapid and long-lasting effects. 3. This invention achieves green preparation and long-term storage stability of the composition through a complete process design. Organic solvents are eliminated throughout the process, and deionized water is used as the sole dispersion medium. Sodium lignosulfonate is derived from a renewable byproduct of the papermaking industry. Ascorbyl palmitate and arginine are both natural-source auxiliaries. Carvacrol and neem oil are formulated at low temperature under nitrogen protection to enhance the oil phase, effectively preventing oxidation of active ingredients. The filling process is protected by nitrogen and sealed in light-proof HDPE bottles with aluminum foil composite lining to isolate the deterioration of the product by oxygen and ultraviolet rays. This invention provides a new solution for the green control of citrus psyllids that combines high-efficiency control, long-lasting effect, excellent storage stability, and environmental friendliness throughout the entire chain. Detailed Implementation

[0007] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0008] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0009] Example 1 1. Add 420g of deionized water to a reactor equipped with a jacketed heating system and a high-speed dispersion plate. Turn on the reactor stirrer and set the stirrer speed to 200 rpm. Heat the reactor to 45°C using circulating water in the jacket. After the temperature stabilizes, add 250g of water-soluble alkali lignin to the deionized water in batches while stirring. Add each batch 3 minutes apart and add in three batches. After the addition is complete, increase the stirrer speed to 350 rpm and stir continuously for 30 minutes to obtain 665g of dark brown homogeneous lignin solution. 2: Pass 40g of arginine through a 60-mesh sieve. While stirring, add the sieved arginine to the lignin solution. Control the addition time to 10 minutes. After adding, continue stirring for 12 minutes. After standing to defoam, add 50g of oligochitosan and 60g of glycerol in sequence, with an interval of 5 minutes between each addition. After adding, set the stirring speed to 450 rpm and continue stirring for 15 minutes to obtain 811g of wall material solution. 3: The wall material solution is pumped through a diaphragm pump into a plate filter with a 0.8 μm pore size polytetrafluoroethylene filter membrane for vacuum negative pressure filtration. The vacuum degree is -0.075 MPa. The filtrate is collected in a clean receiving tank to obtain 803 g of refined wall material solution. The cooling water in the jacket of the receiving tank is turned on to cool the refined wall material aqueous phase to 25°C for later use. 4. Add 120g of neem oil to a light-proof treatment vessel equipped with a jacketed heating and reflux condenser. Turn on the stirrer and set the speed to 100 rpm. Heat the vessel to 38°C using a jacketed water bath. After the temperature stabilizes, add 40g of carvacrol and 20g of ascorbyl palmitate in sequence. After the addition is complete, increase the stirrer speed to 150 rpm and stir and mix for 18 minutes under a nitrogen protective atmosphere. Throughout the mixing process, the treatment vessel maintains a nitrogen atmosphere through the reflux condenser. After mixing, let it stand for 5 minutes to obtain 178g of reddish-brown transparent enhanced oil phase. Transfer the enhanced oil phase to a brown reagent bottle that has been pre-purged with nitrogen using a metering pump. After the transfer, purge the bottle with nitrogen again for 30 seconds to purge the air at the bottle opening. Seal immediately and store in the dark for later use. 5. Transfer the refined wall material solution to the emulsification tank of a high-speed shear emulsifier. The emulsification tank is equipped with a circulating cooling jacket and a low-temperature constant temperature circulation tank is pre-connected and the circulating liquid temperature is set to 25℃. Circulation is started for 30 minutes to stabilize the temperature of the inner wall of the emulsification tank. The enhanced oil phase is added to a constant temperature dropping tank with magnetic stirring. The temperature of the constant temperature dropping tank is set to 25℃ and the stirring speed is 80 rpm. The high-speed shear emulsifier is started and the shearing speed is set to 5000 rpm for pre-dispersion. At the same time, the peristaltic pump is turned on to slowly inject the enhanced oil phase into the water phase of the wall material at a constant rate of 1 ml / s through a stainless steel dropping tube with an inner diameter of 2 mm. During the dropping process, the shearing speed is gradually increased to 12000 rpm. After the dropping is completed, the shearing speed is maintained at 12000 rpm for 10 minutes. During the shearing process, the emulsion temperature is controlled not to exceed 30℃ by the circulating cooling jacket to obtain 978g of nanocapsule suspension. 6: The nanocapsule suspension was transferred to an aging vessel equipped with an anchor stirrer and a jacketed temperature control via a rotary pump. The stirring speed was set to 120 rpm, and the suspension was stirred and aged at room temperature for 45 minutes. During the aging process, 5 ml of sample was taken from the sampling valve every 15 minutes to observe the state of the suspension and confirm that there was no stratification or flocculation. After the aging was completed, 0.59 g of polydimethylsiloxane emulsion defoamer was added to the aging vessel. After the addition, the stirring speed was briefly increased to 200 rpm and stirred for 3 minutes for rapid dispersion. Then, the stirring speed was restored to 120 rpm and stirred for another 5 minutes for defoaming. After defoaming was completed, the suspension was allowed to stand for 10 minutes to obtain 962 g of aged nanocapsule suspension. 7: The aged nanocapsule suspension was connected to the feed buffer tank of the filling machine with an 80-mesh stainless steel online filter via a hose. The feed buffer tank was equipped with a low-speed anchor stirrer, and the stirring speed was set to 60 rpm to prevent the suspension from settling. Before filling, the filling pipeline and filling head were purged with nitrogen for 30 seconds to remove air. The filling container was a light-proof HDPE bottle with an aluminum foil composite liner. Nitrogen gas was used for protection during the filling process. The filling volume was 85% of the bottle's internal volume. After filling, the cap was immediately screwed on and sealed. The sealing of each bottle was checked, and the defective products were rejected to obtain the neem essential oil composition for controlling psyllids prepared in Example 1.

[0010] Example 2 1. Add 415g of deionized water to a reactor equipped with a jacketed heating system and a high-speed dispersion plate. Turn on the reactor stirrer and set the stirrer speed to 200 rpm. Heat the reactor to 45°C using circulating water in the jacket. After the temperature stabilizes, add 300g of water-soluble alkali lignin to the deionized water in batches while stirring. Add each batch 3 minutes apart and add in three batches. After the addition is complete, increase the stirrer speed to 350 rpm and stir continuously for 30 minutes to obtain 709g of dark brown homogeneous lignin solution. 2: Pass 20g of arginine through a 60-mesh sieve. While stirring, add the sieved arginine to the lignin solution. Control the addition time to 10 minutes. After adding, continue stirring for 12 minutes. After standing to defoam, add 20g of oligochitosan and 30g of glycerol in sequence, with an interval of 5 minutes between each addition. After adding, set the stirring speed to 450 rpm and continue stirring for 15 minutes to obtain 775g of wall material solution. 3: The wall material solution is pumped through a diaphragm pump into a plate filter with a 0.8 μm pore size polytetrafluoroethylene filter membrane for vacuum negative pressure filtration. The vacuum degree is -0.075 MPa. The filtrate is collected in a clean receiving tank to obtain 767 g of refined wall material solution. The cooling water in the jacket of the receiving tank is turned on to cool the refined wall material aqueous phase to 25°C for later use. 4. Add 150g of neem oil to a light-proof treatment vessel equipped with a jacketed heating and reflux condenser. Turn on the stirrer and set the speed to 100 rpm. Heat the vessel to 38°C using a jacketed water bath. After the temperature stabilizes, add 60g of carvacrol and 5g of ascorbyl palmitate in sequence. After the addition is complete, increase the stirrer speed to 150 rpm and stir and mix for 18 minutes under a nitrogen protective atmosphere. Throughout the mixing process, the treatment vessel maintains a nitrogen atmosphere through the reflux condenser. After mixing, let it stand for 5 minutes to obtain 213g of reddish-brown transparent enhanced oil phase. Transfer the enhanced oil phase to a brown reagent bottle that has been pre-purged with nitrogen using a metering pump. After the transfer, purge the bottle with nitrogen again for 30 seconds to purge the air from the bottle opening. Seal immediately and store in the dark for later use. 5. Transfer the refined wall material solution to the emulsification tank of a high-speed shear emulsifier. The emulsification tank is equipped with a circulating cooling jacket and a low-temperature constant temperature circulation tank is pre-connected and the circulating liquid temperature is set to 25℃. Circulation is started for 30 minutes to stabilize the temperature of the inner wall of the emulsification tank. Add the enhanced oil phase to a constant temperature dropping tank with magnetic stirring. Set the temperature of the constant temperature dropping tank to 25℃ and the stirring speed to 80 rpm. Start the high-speed shear emulsifier and set the shearing speed to 5000 rpm for pre-dispersion. At the same time, start the peristaltic pump to slowly inject the enhanced oil phase into the water phase of the wall material at a constant rate of 1 ml / s through a stainless steel dropping tube with an inner diameter of 2 mm. During the dropping process, the shearing speed is gradually increased to 12000 rpm. After the dropping is completed, shearing is maintained at 12000 rpm for 10 minutes. During the shearing process, the emulsion temperature is controlled not to exceed 30℃ by the circulating cooling jacket to obtain 975g of nanocapsule suspension. 6: The nanocapsule suspension was transferred to an aging vessel equipped with an anchor stirrer and a jacketed temperature control via a rotary pump. The stirring speed was set to 120 rpm, and the suspension was aged at room temperature for 45 minutes. During the aging process, 5 ml of sample was taken from the sampling valve every 15 minutes to observe the state of the suspension and confirm that there was no stratification or flocculation. After the aging was completed, 0.585 g of polydimethylsiloxane emulsion defoamer was added to the aging vessel. After the addition, the stirring speed was briefly increased to 200 rpm and stirred for 3 minutes for rapid dispersion. Then, the stirring speed was restored to 120 rpm and stirred for another 5 minutes for defoaming. After defoaming was completed, the suspension was allowed to stand for 10 minutes to obtain 959 g of aged nanocapsule suspension. 7: The aged nanocapsule suspension was connected to the feed buffer tank of the filling machine with an 80-mesh stainless steel online filter via a hose. The feed buffer tank was equipped with a low-speed anchor stirrer, and the stirring speed was set to 60 rpm to prevent the suspension from settling. Before filling, the filling pipeline and filling head were purged with nitrogen for 30 seconds to remove air. The filling container was a light-proof HDPE bottle with an aluminum foil composite liner. Nitrogen gas was used for protection during the filling process. The filling volume was 85% of the bottle's internal volume. After filling, the cap was immediately screwed on and sealed. The sealing of each bottle was checked, and products with poor sealing were rejected to obtain the neem essential oil composition for controlling psyllids prepared in Example 2.

[0011] Comparative Example 1 The difference between this comparative example and Example 1 is that water-soluble alkali lignin is not used as the nanocapsule wall material, but an equal amount of conventional surfactant sodium dodecylbenzenesulfonate is used instead. The specific preparation method is as follows: 1. Add 420g of deionized water to a reactor equipped with a jacketed heating system and a high-speed dispersion plate. Turn on the reactor stirrer and set the stirrer speed to 200 rpm. Heat the reactor to 45°C using circulating water in the jacket. After the temperature stabilizes, add 250g of sodium dodecylbenzenesulfonate to the deionized water in batches while stirring. Add each batch 3 minutes apart and add in three batches. After the addition is complete, increase the stirrer speed to 350 rpm and stir continuously for 30 minutes to obtain 665g of surfactant solution. 2: Pass 40g of arginine through a 60-mesh sieve. While stirring, add the sieved arginine to the surfactant solution. Control the addition time to 10 minutes. After adding, continue stirring for 12 minutes. After standing to defoam, add 50g of oligochitosan and 60g of glycerol in sequence, with an interval of 5 minutes between each addition. After adding, set the stirring speed to 450 rpm and continue stirring for 15 minutes to obtain 811g of emulsifier solution. 3: The emulsifier solution is pumped through a diaphragm pump into a plate filter with a 0.8μm pore size polytetrafluoroethylene filter membrane for vacuum negative pressure filtration at a vacuum degree of -0.075MPa. The filtrate is collected in a clean receiving tank to obtain 803g of refined emulsifier solution. The cooling water in the jacket of the receiving tank is turned on to cool the refined emulsifier solution to 25℃ for later use. 4. Add 120g of neem oil to a light-proof treatment vessel equipped with a jacketed heating and reflux condenser. Turn on the stirrer and set the speed to 100 rpm. Heat the vessel to 38°C using a jacketed water bath. After the temperature stabilizes, add 40g of carvacrol and 20g of ascorbyl palmitate in sequence. After the addition is complete, increase the stirrer speed to 150 rpm and stir and mix for 18 minutes under a nitrogen protective atmosphere. Throughout the mixing process, the treatment vessel maintains a nitrogen atmosphere through the reflux condenser. After mixing, let it stand for 5 minutes to obtain 178g of reddish-brown transparent enhanced oil phase. Transfer the enhanced oil phase to a brown reagent bottle that has been pre-purged with nitrogen using a metering pump. After the transfer, purge the bottle with nitrogen again for 30 seconds to purge the air at the bottle opening. Seal immediately and store in the dark for later use. 5. Transfer the refined emulsifier solution to the emulsification vessel of the high-speed shear emulsifier. The emulsifier is equipped with a circulating cooling jacket and a low-temperature constant temperature circulation tank is pre-connected and the circulating liquid temperature is set to 25℃. Circulation is started for 30 minutes to stabilize the temperature of the inner wall of the emulsifier. The enhanced oil phase is added to a constant temperature dropping tank with magnetic stirring. The temperature of the constant temperature dropping tank is set to 25℃ and the stirring speed is 80 rpm. The high-speed shear emulsifier is started and the shearing speed is set to 5000 rpm for pre-dispersion. At the same time, the peristaltic pump is turned on to slowly inject the enhanced oil phase into the emulsifier solution at a constant rate of 1 ml / s through a stainless steel dropping tube with an inner diameter of 2 mm. During the dropping process, the shearing speed is gradually increased to 12000 rpm. After the dropping is completed, the shearing speed is maintained at 12000 rpm for 10 minutes. During the shearing process, the emulsion temperature is controlled not to exceed 30℃ by the circulating cooling jacket to obtain 978g of conventional emulsion. 6: The conventional emulsion was transferred to an aging vessel equipped with an anchor stirrer and a jacketed temperature control via a rotary pump. The stirring speed was set to 120 rpm, and the emulsion was aged at room temperature for 45 minutes. During the aging process, 5 ml of sample was taken from the sampling valve every 15 minutes to observe the emulsion state and confirm that there was no stratification or flocculation. After the aging was completed, 0.587 g of polydimethylsiloxane emulsion-type defoamer was added to the aging vessel. After the addition, the stirring speed was briefly increased to 200 rpm and stirred for 3 minutes for rapid dispersion. Then, the stirring speed was restored to 120 rpm and stirred for another 5 minutes for defoaming. After defoaming was completed, the mixture was allowed to stand for 10 minutes to obtain 962 g of aged emulsion. 7: Connect the aged emulsion to the feed buffer tank of the filling machine equipped with an 80-mesh stainless steel online filter via a hose. The feed buffer tank is equipped with a low-speed anchor agitator, and the agitation speed is set at 60 rpm to prevent emulsion sedimentation. Before filling, purge the filling pipeline and filling head with nitrogen for 30 seconds to remove air. Use light-proof HDPE bottles with aluminum foil composite liners as filling containers. Nitrogen gas is used for protection during the filling process. The filling volume is 85% of the bottle's internal volume. Immediately after filling, screw the cap on and seal the bottle. Check the sealing of each bottle and discard those with poor sealing to obtain the neem essential oil composition for controlling psyllids prepared in Comparative Example 1.

[0012] Comparative Example 2 The difference between this comparative example and Example 1 is that carvacrol is not used; only neem oil is used as the single active ingredient, and the carvacrol and neem oil are not combined for synergistic effects. The specific preparation method is as follows: 1. Add 460g of deionized water to a reactor equipped with a jacketed heating system and a high-speed dispersion plate. Turn on the reactor stirrer and set the stirrer speed to 200 rpm. Heat the reactor to 45°C using circulating water in the jacket. After the temperature stabilizes, add 250g of water-soluble alkali lignin to the deionized water in batches while stirring. Add each batch 3 minutes apart and add in three batches. After the addition is complete, increase the stirrer speed to 350 rpm and stir continuously for 30 minutes to obtain 704g of dark brown homogeneous lignin solution. 2: Pass 40g of arginine through a 60-mesh sieve. While stirring, add the sieved arginine to the lignin solution. Control the addition time to 10 minutes. After adding, continue stirring for 12 minutes. After standing to defoam, add 50g of oligochitosan and 60g of glycerol in sequence, with an interval of 5 minutes between each addition. After adding, set the stirring speed to 450 rpm and continue stirring for 15 minutes to obtain 850g of wall material solution. 3: The wall material solution is pumped through a diaphragm pump into a plate filter with a 0.8μm pore size polytetrafluoroethylene filter membrane for vacuum negative pressure filtration. The vacuum degree is -0.075MPa. The filtrate is collected in a clean receiving tank to obtain 842g of refined wall material solution. The cooling water in the jacket of the receiving tank is turned on to cool the refined wall material aqueous phase to 25℃ for later use. 4. Add 120g of neem oil to a light-proof treatment vessel equipped with a jacketed heating and reflux condenser. Turn on the stirrer and set the speed to 100 rpm. Heat the vessel to 38°C using a jacketed water bath. After the temperature stabilizes, add 20g of ascorbyl palmitate. After the addition is complete, increase the stirrer speed to 150 rpm and stir for 18 minutes under a nitrogen protective atmosphere. Throughout the mixing process, maintain a nitrogen atmosphere in the treatment vessel through the reflux condenser. After mixing, let stand for 5 minutes to obtain 139g of reddish-brown transparent enhanced oil phase. Transfer the enhanced oil phase to a brown reagent bottle that has been pre-purged with nitrogen using a metering pump. After the transfer, purge the bottle with nitrogen again for 30 seconds to purge the air from the bottle opening. Seal immediately and store in the dark for later use. 5. Transfer the refined wall material solution to the emulsification tank of a high-speed shear emulsifier. The emulsification tank is equipped with a circulating cooling jacket and a low-temperature constant temperature circulation tank is pre-connected and the circulating liquid temperature is set to 25℃. Circulation is started for 30 minutes to stabilize the temperature of the inner wall of the emulsification tank. The enhanced oil phase is added to a constant temperature dropping tank with magnetic stirring. The temperature of the constant temperature dropping tank is set to 25℃ and the stirring speed is 80 rpm. The high-speed shear emulsifier is started and the shearing speed is set to 5000 rpm for pre-dispersion. At the same time, the peristaltic pump is turned on to slowly inject the enhanced oil phase into the water phase of the wall material at a constant rate of 1 ml / s through a stainless steel dropping tube with an inner diameter of 2 mm. During the dropping process, the shearing speed is gradually increased to 12000 rpm. After the dropping is completed, the shearing speed is maintained at 12000 rpm for 10 minutes. During the shearing process, the emulsion temperature is controlled not to exceed 30℃ by the circulating cooling jacket to obtain 978g of nanocapsule suspension. 6: The nanocapsule suspension was transferred to an aging vessel equipped with an anchor stirrer and a jacketed temperature control via a rotary pump. The stirring speed was set to 120 rpm, and the suspension was stirred and aged at room temperature for 45 minutes. During the aging process, 5 ml of sample was taken from the sampling valve every 15 minutes to observe the state of the suspension and confirm that there was no stratification or flocculation. After the aging was completed, 0.587 g of polydimethylsiloxane emulsion defoamer was added to the aging vessel. After the addition, the stirring speed was briefly increased to 200 rpm and stirred for 3 minutes for rapid dispersion. Then, the stirring speed was restored to 120 rpm and stirred for another 5 minutes for defoaming. After defoaming was completed, the suspension was allowed to stand for 10 minutes to obtain 962 g of aged nanocapsule suspension. 7: The aged nanocapsule suspension was connected to the feed buffer tank of a filling machine equipped with an 80-mesh stainless steel online filter via a hose. The feed buffer tank was equipped with a low-speed anchor stirrer, and the stirring speed was set to 60 rpm to prevent the suspension from settling. Before filling, the filling pipeline and filling head were purged with nitrogen for 30 seconds to remove air. The filling container was a light-proof HDPE bottle with an aluminum foil composite liner. Nitrogen gas was used for protection during the filling process. The filling volume was 85% of the bottle's internal volume. After filling, the cap was immediately screwed on and sealed. The sealing of each bottle was checked, and the defective products were rejected to obtain the neem essential oil composition for controlling psyllids prepared in Comparative Example 2.

[0013] Particle size and dispersion stability test The neem essential oil compositions for controlling psyllids prepared in Examples 1, 2, 1, and 2 were diluted 500 times with deionized water. The particle size distribution and zeta potential of the diluted solution were measured using a nanoparticle size and zeta potential analyzer. The diluted solution was allowed to stand at room temperature, and the layering, flocculation, or precipitation were observed and recorded at 0h, 24h, 48h, and 72h, respectively. The test results were recorded. Table 1. Results of particle size and dispersion stability tests Analysis of Table 1 shows that the average particle sizes of Examples 1 and 2 are 385 nm and 412 nm, respectively, and the PDI is less than 0.25, indicating that the nanocapsule particle size distribution is uniform. The absolute values ​​of the Zeta potentials are both greater than 39 mV, indicating that the suspension has excellent electrostatic stability. After standing for 72 h, there is no stratification or precipitation, proving that the nanocapsule wall material constructed by sodium lignosulfonate can provide long-term steric hindrance and electrostatic double-layer stabilization. The average particle size of Comparative Example 1 reached 1580 nm, the PDI was as high as 0.68, the absolute value of the Zeta potential was only 18.3 mV, and stratification occurred after 24 h. The reason for this was that sodium dodecylbenzenesulfonate is a small molecule surfactant, which can only form ordinary emulsions rather than nanocapsule structures. The emulsion droplets are prone to aggregation and Ostwald ripening, and the stability of the system is significantly reduced. The average particle size and stability of Comparative Example 2 were comparable to those of Example 1, indicating that the presence or absence of carvacrol had no significant effect on the particle size and physical stability of the nanocapsules.

[0014] UV degradation test The neem oil compositions for controlling psyllids prepared in Examples 1, 2, Comparative Example 1, and Comparative Example 2 were diluted 500 times with deionized water. Equal volumes of the diluted solutions were placed in quartz cuvettes and irradiated in a UV aging test chamber (UV-A lamp, wavelength 365 nm, irradiance 5.0 mW / cm²). 2 Samples were taken at 0h, 24h, 48h and 72h after irradiation. The residual rate of azadirachtin was determined by high performance liquid chromatography, the photodegradation half-life was calculated and the test results were recorded. Table 2. Results of UV degradation test Analysis of Table 2 shows that after 72 hours of UV irradiation, the azadirachtin residue rates of Examples 1 and 2 were 61.8% and 56.5%, respectively, and the half-lives were 98.5 hours and 85.3 hours, respectively. This demonstrates that the polyphenolic aromatic ring structure of the sodium lignosulfonate wall material has natural UV absorption capacity and can effectively shield the degradation effect of UV light on the core material azadirachtin essential oil. The UV protection effect of Example 1 is slightly better than that of Example 2. The reason for this is that the proportion of sodium lignosulfonate in the core material is higher in Example 1, the wall material is relatively sufficient, and the UV shielding layer is denser. Comparative Example 1 showed that the azadirachtin residue rate was only 12.5% ​​after 72 hours, and the half-life was only 25.8 hours. The photodegradation rate was 3.8 times that of Example 1. The reason for this was that sodium dodecylbenzene sulfonate did not have the ability to absorb ultraviolet light, and the azadirachtin essential oil was rapidly photodegraded when exposed to ultraviolet light. This proves that the contribution of sodium lignosulfonate nanocapsule wall material to ultraviolet protection is irreplaceable. The UV stability of Comparative Example 2 was similar to that of Example 1, indicating that the addition of carvacrol did not have a negative impact on the UV shielding function of the lignin wall material.

[0015] Indoor toxicity test of citrus psyllid The neem essential oil compositions for controlling psyllids prepared in Examples 1, 2, 1, and 2 were diluted with deionized water to five concentration gradients of 125, 250, 500, 1000, and 2000 times. Using tender citrus shoots with leaves as host material, the third instar nymphs of citrus psyllids were treated by immersion method, with 30 nymphs per treatment, repeated 3 times. After 72 hours, the number of dead nymphs was checked, and the corrected mortality rate and LC50 value were calculated. A blank control of water was set up at the same time, and the test results were recorded. Table 3. Results of indoor toxicity assay for 3rd instar nymphs of the citrus psyllid (72h). Analysis of Table 3 shows that the LC50 of Examples 1 and 2 against the third instar nymphs of citrus psyllids were 1680 times and 1420 times, respectively. The corrected mortality rates of the 500-fold dilutions after 72 hours reached 88.5% and 82.8%, respectively, demonstrating excellent insecticidal activity. The toxicity of Example 1 was slightly higher than that of Example 2. The reason for this is that the mass ratio of the synergistic oil phase to the wall material was better in Example 1, the nanocapsule encapsulation efficiency and drug loading were better balanced, and the sustained-release delivery efficiency of neem oil was higher. The LC50 of Comparative Example 1 was only 620 times, and the mortality rate of the 500-fold dilution was only 46.2%, indicating that the insecticidal activity was significantly lower than that of Example 1. The reason for this was that the conventional emulsion prepared with sodium dodecylbenzenesulfonate broke down rapidly after dilution, and the neem oil and carvacrol were separated and volatilized in large quantities before application, so the active ingredients could not be effectively delivered to the surface of the target pests. The LC50 of Comparative Example 2 was 1250 times, and the mortality rate corrected for a 500-fold dilution was 68.5%. Its insecticidal activity was between that of Example 1 and Comparative Example 1. The reason for this was the lack of synergistic effect of carvacrol. When used alone, neem oil has limited antifeedant and toxic activity, and it lacks the inhibitory effect of carvacrol on the detoxification enzyme system of citrus psyllids. This proves that the combination of neem oil and carvacrol has a significant synergistic effect.

[0016] Field efficacy test for controlling citrus psyllids The neem essential oil compositions for controlling psyllids prepared in Examples 1, 2, 1, and 2 were diluted 500 times with water and field spraying experiments were conducted during the peak occurrence period of citrus psyllids. Three citrus trees were selected for each treatment, and 2L of water was sprayed per tree. Water was used as a blank control. The number of citrus psyllid nymphs and adults was investigated at 1, 3, 7, and 14 days after application. The insect population reduction rate was calculated and the test results were recorded. Table 4. Results of field efficacy trials for controlling citrus psyllids Analysis of Table 4 shows that the reduction rates of adult insects in Examples 1 and 2 were 68.5% and 72.8% respectively 1 day after application, demonstrating good rapid efficacy. This is attributed to the fact that carvacrol has fumigation and contact killing activity, which can quickly knock down adult citrus psyllids. The nymph reduction rates reached a peak of 85.8% and 82.5% 7 days after application, and remained at 72.5% and 68.8% after 14 days. The duration of efficacy was significantly better than that of conventional formulations, proving that the sodium lignosulfonate nanocapsule wall material achieved controlled and sustained release of neem oil, continuously exerting its antifeedant and growth-inhibiting effects. Although the nymph and adult reduction rate of Comparative Example 1 was better than that of Comparative Example 2 1 day after application, the control effect dropped sharply after 7 days. The nymph reduction rate was only 22.6% after 14 days. The reason for this was that the conventional emulsion formulation had a short duration of action and the neem oil was rapidly photolyzed, which lacked the ability to continuously control the nymphs that hatched later. In Comparative Example 2, the adult reduction rate was only 42.6% one day after application, indicating insufficient rapid efficacy. This was attributed to the lack of fumigation knockdown effect from carvacrol. The neem oil alone needs to work indirectly through feeding refusal and molting interference, resulting in a slower onset of action. After 14 days, the nymph reduction rate was 35.8%, showing weaker residual efficacy than in Example 1. This demonstrates that carvacrol and neem oil have a synergistic effect under field conditions, and their combined use can simultaneously enhance both rapid and residual efficacy.

[0017] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An azadirachtin oil composition for controlling psylids, characterized by, It consists of the following ingredients by weight percentage: 12-15% neem oil, 4-6% carvacrol, 25-30% water-soluble alkali lignin, 2-4% arginine, 2-5% oligochitosan, 3-6% glycerol, 0.5-2% ascorbyl palmitate and the balance being deionized water.

2. The azadirachtin oil composition for controlling wood lice according to claim 1, wherein The molecular weight of the oligochitosan is ≤3000 Da, and the degree of deacetylation is ≥90%.

3. The azadirachtin oil composition for controlling wood lice according to claim 1, wherein The water-soluble alkali lignin is sodium lignin sulfonate, with a lignin content ≥85wt%, ash content ≤5wt%, moisture content ≤8wt%, and a pH value of 8-10 for a 1% aqueous solution.

4. The azadirachtin oil composition for controlling wood lice according to claim 1, wherein The neem oil mentioned is extracted by cold pressing and has an azadirachtin content of ≥1500ppm.

5. A process for the preparation of Azadirachtin oil composition for the control of psylids as claimed in claim 1, wherein, Includes the following steps: S1: Add deionized water to a reactor equipped with a jacketed heating system and a high-speed dispersion plate. Turn on the reactor stirrer and set the stirrer speed to 200 rpm. Heat the reactor to 45°C using circulating water in the jacket. After the temperature stabilizes, add water-soluble alkali lignin to the deionized water in batches while stirring. Add each batch 3 minutes apart and add in three batches. After the addition is complete, increase the stirrer speed to 350 rpm and continue stirring for 30 minutes to obtain a dark brown, homogeneous lignin solution. S2: Pass arginine through a 60-mesh sieve. Add the sieved arginine to the lignin solution while stirring. Control the addition time to 10 minutes. After adding, continue stirring for 12 minutes. After standing to defoam, add oligochitosan and glycerol in sequence, with an interval of 5 minutes between each addition. After adding, set the stirring speed to 450 rpm and continue stirring for 15 minutes to obtain the wall material solution. S3: The wall material solution is pumped through a diaphragm pump into a plate filter with a 0.8 μm pore size polytetrafluoroethylene filter membrane for vacuum negative pressure filtration. The vacuum degree is -0.075 MPa. The filtrate is collected in a clean receiving tank to obtain a refined wall material solution. The cooling water in the jacket of the receiving tank is turned on to cool the refined wall material aqueous phase to 25°C for later use. S4: Add neem essential oil to a light-proof treatment vessel equipped with a jacketed heating and reflux condenser. Turn on the stirrer of the treatment vessel and set the speed to 100 rpm. Heat the vessel to 38°C through a jacketed water bath. After the temperature stabilizes, add carvacrol and ascorbyl palmitate in sequence. After the addition is complete, increase the stirrer speed to 150 rpm and stir and mix for 18 minutes under a nitrogen protective atmosphere. Throughout the mixing process, the treatment vessel maintains a nitrogen atmosphere through the reflux condenser. After mixing, let it stand for 5 minutes to obtain a reddish-brown transparent enhanced oil phase. Transfer the enhanced oil phase to a brown reagent bottle that has been pre-purged with nitrogen using a metering pump. After the transfer, purge the bottle with nitrogen again for 30 seconds to purge the air at the bottle opening. Seal immediately and store in the dark for later use. S5: Transfer the refined wall material solution to the emulsification tank of the high-speed shear emulsifier. The emulsifier is equipped with a circulating cooling jacket and a low-temperature constant temperature circulation tank is pre-connected and the circulating liquid temperature is set to 25℃. Circulation is started for 30 minutes to stabilize the temperature of the inner wall of the emulsifier. Add the enhanced oil phase to the constant temperature dropping tank with magnetic stirring. Set the temperature of the constant temperature dropping tank to 25℃ and the stirring speed to 80 rpm. Start the high-speed shear emulsifier and set the shearing speed to 5000 rpm for pre-dispersion. At the same time, turn on the peristaltic pump to slowly inject the enhanced oil phase into the wall material aqueous phase at a constant rate of 1 ml / s through a stainless steel dropping tube with an inner diameter of 2 mm. During the dropping process, the shearing speed is gradually increased to 12000 rpm. After the dropping is completed, maintain the shearing speed at 12000 rpm for 10 minutes. During the shearing process, the emulsion temperature is controlled not to exceed 30℃ by the circulating cooling jacket to obtain a nanocapsule suspension. S6: The nanocapsule suspension was transferred to an aging vessel equipped with an anchor stirrer and a jacketed temperature control via a rotary pump. The stirring speed was set to 120 rpm, and the suspension was aged at room temperature for 45 minutes. During the aging process, 5 ml of sample was taken from the sampling valve every 15 minutes to observe the state of the suspension and confirm that there was no stratification or flocculation. After the aging was completed, an organosilicon defoamer was added to the aging vessel. After the addition, the stirring speed was briefly increased to 200 rpm and stirred for 3 minutes for rapid dispersion. Then, the stirring speed was restored to 120 rpm and stirred for another 5 minutes for defoaming. After defoaming was completed, the suspension was allowed to stand for 10 minutes to obtain the aged nanocapsule suspension. S7: Connect the aged nanocapsule suspension to the feed buffer tank of the filling machine equipped with an 80-mesh stainless steel online filter via a hose. The feed buffer tank is equipped with a low-speed anchor agitator, and the agitation speed is set to 60 rpm to prevent the suspension from settling. Before filling, purge the filling pipeline and filling head with nitrogen for 30 seconds to remove air. Use light-proof HDPE bottles with aluminum foil composite liners as filling containers. Nitrogen gas is used for protection during the filling process. The filling volume is 85% of the bottle's internal volume. Immediately after filling, screw the cap on and seal the bottle. Check the sealing of each bottle and discard those with poor sealing to obtain the neem essential oil composition for controlling psyllids.

6. An azadirachtin oil composition for controlling wood lice according to claim 1, wherein The silicone defoamer mentioned in step S6 is a polydimethylsiloxane emulsion type defoamer, and the mass ratio of the silicone defoamer to the nanocapsule suspension is 0.06:100.

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