A method for controlling dendrolimus punctatus walker

Abstract

This invention discloses a method for controlling pine caterpillars in Pinus sylvestris, belonging to the field of pine caterpillar control technology. The specific control method is as follows: (1) Control of overwintering generation: Turn over the dead branches and fallen leaves around the trunk to expose the pine caterpillars overwintering underground and reduce the number of overwintering pine caterpillars; (2) Control during the tree climbing period: Use pine caterpillar control agents to kill the larvae climbing the tree; (3) Control of adult insects: Use black light to trap adult pine caterpillars to reduce their reproduction and reduce the number of insects in the following year; (4) Control during the tree leaving period: Use pine caterpillar control agents to kill the pine caterpillars that have overwintered after leaving the tree; The combined biological and physical control methods alleviate the pine caterpillar pest in Pinus sylvestris and solve the problem that the effect of Beauveria bassiana in controlling pine caterpillars is easily affected by the environment and the effect is unstable.

Description

Technical Field

[0001] This invention relates to the field of pine caterpillar control technology, and in particular to a method for controlling pine caterpillars in Pinus sylvestris. Background Technology

[0002] Scots pine (Pinus sylvestris) is an evergreen tree belonging to the genus Pinus in the family Pinaceae. It is a major afforestation species in Northeast my country, possessing high economic value and playing an irreplaceable role in maintaining forest ecological security and conserving water resources. However, with the continuous increase in the area of ​​monoculture forests, pest and disease problems of Scots pine are becoming increasingly serious, posing a major obstacle to the sustainable development of the Scots pine industry.

[0003] Pine caterpillars are one of the major pests of Scots pine. In winter, they descend from the trees to overwinter in dead leaves. Every April, as temperatures rise, the caterpillars climb the trees and feed on the pine needles, causing widespread needle drop and, in severe cases, the death of entire pine forests. Current control methods for pine caterpillars include chemical, physical, and biological control. Chemical control is suitable for outbreaks, is fast-acting, and highly efficient, but long-term use can lead to resistance and is toxic to the caterpillars' natural enemies. Physical control involves using phototaxis to trap adult caterpillars or binding tape to the trunks to prevent larvae from climbing; it is simple to operate and has no pesticide damage, but its effectiveness is short-lived. Biological control utilizes natural enemies, pathogens, or competing organisms to control pest populations. It is less prone to resistance development and is environmentally friendly and sustainable, making it the most widely used control method at present. However, the effectiveness of biological control is greatly affected by the environment and its results are unstable. Among biological control methods, the most common is the use of Beauveria bassiana as a biocontrol fungus. Beauveria bassiana can parasitize pine caterpillars through contact with their body walls under natural conditions. Under suitable humidity, spores germinate, invade the insect's body, multiply within it, consume its nutrients, and produce a large number of hyphae and spores, ultimately leading to the insect's death. However, Beauveria bassiana spore germination requires high humidity, and its activity decreases under prolonged natural light, resulting in slow infection and unstable control effects. Therefore, there is an urgent need for a low-toxicity, highly effective, and stable control method to manage pine caterpillar disease in Pinus sylvestris. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a method for controlling pine caterpillars in Pinus sylvestris, which utilizes a combination of biological and physical methods to alleviate pine caterpillar infestation and solves the problem that Beauveria bassiana is easily affected by the environment and has unstable efficacy in controlling pine caterpillars.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] A method for controlling the pine caterpillar of Pinus sylvestris:

[0007] (1) Control of overwintering generation: Turn over the dead branches and fallen leaves around the trunk to expose the pine caterpillars that are overwintering underground, thereby reducing the number of overwintering pine caterpillars.

[0008] (2) Control during the tree climbing period: After brushing the pine caterpillar control agent onto the trunk of the Pinus sylvestris tree, spray water to moisten it and kill the larvae climbing the tree;

[0009] (3) Adult control: Use black light traps to capture adult pine caterpillars to reduce their reproduction and lower the number of insects in the following year.

[0010] (4) Control during the fall period: After brushing the pine caterpillar control agent onto the trunk of the Pinus sylvestris tree, spray water to moisten it and kill the larvae that fall from the tree.

[0011] Furthermore, the overwintering generation control is carried out in January, the tree-planting control is carried out in mid-April, the adult insect control is carried out in July-August, and the tree-down control is carried out in November.

[0012] Furthermore, the method of using the pine caterpillar control agent is to apply the pine caterpillar control agent to the trunk at a position 1-1.2m above the ground, forming a closed ring of 8-10cm wide on the trunk of the Pinus sylvestris tree. The application amount is 30-40g / tree, and the water spraying amount is 20-25g / tree. Preferably, a closed ring of 10cm wide is applied to the trunk at a position 1m above the ground, with an application amount of 40g / tree and a water spraying amount of 25g / tree.

[0013] Pine caterpillars begin to descend from the trees in November each year to overwinter under the layer of dead branches and leaves on the ground. In April of the following year, when the temperature rises, the pine caterpillars begin to climb the trees to feed, and the adult pine caterpillars begin to lay eggs in July and August. In January, the weather is cold and dry, and pine caterpillars overwinter in the layer of dead branches and fallen leaves. At this time, turning over the layer of dead branches and fallen leaves with tools will destroy the overwintering sites of the pine caterpillars, exposing the overwintering generation of pine caterpillars, causing them to die under environmental influences, thus reducing the overwintering pine caterpillar population. In April, the 3rd-4th instar pine caterpillar larvae begin to climb trees to feed. At this time, the pine caterpillars are weak and have the best time for control. Apply pine caterpillar control agents to the tree trunks. When the pine caterpillars climb the tree and crawl over the control agents, the friction with the gel particles in the control agents will cause the gel particles to break, exposing the inner gel layer that adheres to the pine caterpillars. The liposomes in the inner gel layer fuse with the pine caterpillars' epidermis, and the Beauveria bassiana inside the liposomes is released and quickly invades the pine caterpillars' bodies. It uses the gel and the water inside the pine caterpillars' bodies to germinate rapidly, infecting the pine caterpillars and causing them to die. Using control agents shortens the infection time of Beauveria bassiana and improves the control efficiency of Beauveria bassiana. From July to August, pine caterpillars enter their adult stage and begin laying eggs after emerging from the trees. At this time, black light traps can be used at night to attract and kill adult caterpillars, reducing egg laying and thus lowering the insect population for the following year. In November, as temperatures drop, the larvae of the next generation begin to descend from the trees to overwinter. At this time, pine caterpillar control agents can be applied to the tree trunks to kill the larvae descending from the trees to overwinter, reducing their number and achieving good control results.

[0014] Furthermore, the preparation method of the pine caterpillar control agent is as follows:

[0015] S1: Add Beauveria bassiana spore powder and Tween 80 to PBS solution and stir evenly; dissolve soybean lecithin and cholesterol in anhydrous ethanol, and rotary evaporate at 45℃ for 30-40 min to obtain lipid membrane; mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder to obtain liposome suspension.

[0016] S2: Acrylic acid is dissolved in water to prepare an acrylic acid solution. 30wt% sodium hydroxide solution is added to the acrylic acid solution to adjust the pH to 6.8-7.2. Then glycerol, ammonium persulfate and N,N-methylenebisacrylamide are added. After stirring evenly, the mixture is allowed to stand for 1 hour. Then liposome suspension is added and stirred evenly. After standing for 2-3 hours, sodium polyacrylate gel is obtained. Sodium polyacrylate gel is freeze-dried and then pulverized to obtain sodium polyacrylate gel particles.

[0017] S3: Add diatomaceous earth to water, sonicate for 20-30 minutes, then add 2-2.5 wt% sodium alginate solution and stir evenly to obtain sodium alginate mixed solution. Spray the sodium alginate mixed solution onto the surface of sodium polyacrylate gel particles, then spray 2.5-3 wt% calcium chloride solution, let stand for crosslinking for 30-40 minutes, dry at 30-40℃, and then pulverize to obtain composite gel particles;

[0018] S4: Add the composite gel particles to a mixed solution of xanthan gum, sodium lignosulfonate and water and stir until homogeneous to obtain a stable suspension of pine caterpillar control agent.

[0019] Furthermore, the mass ratio of the Beauveria bassiana spore powder, Tween 80, and PBS solution is 1:0.1:100.

[0020] Furthermore, the Beauveria bassiana spore powder contains 30 billion spores per gram.

[0021] Furthermore, the mass ratio of soybean lecithin:cholesterol:Beauveria bassiana spore powder is 3:1:2.

[0022] Furthermore, the mass ratio of the acrylic acid, glycerol, ammonium persulfate, N,N-methylenebisacrylamide, and liposome suspension is (50-55):(5-6):(1-1.2):(1-1.2):(50-55).

[0023] Furthermore, the freeze-drying conditions are as follows: maintaining a pressure of 10 Pa, a cold trap temperature of -40 °C, and freeze-drying for 24 hours.

[0024] Furthermore, the polypropylene gel particles have a particle size of 1-2 mm, and the composite particles have a particle size of 1.5-2 mm.

[0025] Furthermore, the mass ratio of the diatomaceous earth to the sodium alginate solution is 1:(250-300).

[0026] Furthermore, the mass ratio of the sodium alginate mixed solution to sodium polyacrylate particles is 1:10; the mass ratio of the sodium alginate mixed solution to calcium chloride solution is 2:1.

[0027] Furthermore, the pine caterpillar control agent comprises, by weight percentage: 0.5-1% xanthan gum, 1.5-2% sodium lignosulfonate, 20-25% composite gel particles, and the remainder being water.

[0028] Beauveria bassiana spores require high humidity to germinate and are easily affected by light, losing their activity. This invention prepares Beauveria bassiana into a multi-layered control agent, encapsulating it in a gel to protect its activity from external environmental interference while simultaneously promoting spore germination. However, if Beauveria bassiana directly contacts the gel, it will absorb moisture from the gel before contacting pine caterpillars, germinating prematurely and losing its infectivity. Therefore, this invention embeds Beauveria bassiana within liposomes before mixing it with the gel. The hydrophobic liposomes effectively isolate the Beauveria bassiana from the gel, reducing moisture absorption and preventing premature germination. Upon contact with pine caterpillars, the pine caterpillar control agent releases liposomes loaded with Beauveria bassiana. The liposomes fuse with the pine caterpillar's epidermis, releasing Beauveria bassiana spores to infect the pine caterpillars.

[0029] While gel encapsulation of Beauveria bassiana provides protection, it also has a slow-release effect, making it difficult to control the release time. This invention utilizes sodium alginate and sodium polyacrylate, which have significantly different water absorption rates, to prepare composite gel particles. The water absorption and swelling rate of the sodium polyacrylate inside the composite gel particles is much greater than that of the outer calcium alginate film. This invention prepares an adhesive suspension by combining the composite gel particles with xanthan gum (thickener) and sodium lignosulfonate (dispersant). After being applied to the tree trunk, a suitable amount of water is sprayed to moisten the surface of the control agent. The sodium polyacrylate absorbs water and expands rapidly, stretching and thinning the outer calcium alginate film, which absorbs water slowly and swells. This reduces the strength of the outer calcium alginate film, making it more prone to rupture. Simultaneously, this invention adds diatomaceous earth to the sodium alginate solution. After spraying and forming a film, the diatomaceous earth is embedded in the calcium alginate film. The porous structure of the diatomaceous earth enhances the permeability of the calcium alginate film, allowing the sodium polyacrylate to absorb sufficient water and expand, further promoting the rupture of the outer film. At night, pine caterpillars begin to climb trees. As they crawl over the pine caterpillar control agent, friction occurs with the composite gel particles. At this point, the low-strength calcium alginate film immediately ruptures, exposing the inner, swollen gel that adheres to the caterpillar's surface. The liposomes within the gel dissolve in the caterpillar's epidermis, releasing Beauveria bassiana to infect the caterpillar. The Beauveria bassiana absorbs moisture from the caterpillar's body and the gel, rapidly germinating and killing the caterpillar, achieving a stable and highly effective control. Furthermore, the diatomaceous earth added in this invention can increase the roughness of the composite gel particles, enhancing friction with the caterpillar and potentially damaging the caterpillar's surface, promoting Beauveria bassiana infection and further improving control efficiency.

[0030] Beneficial effects:

[0031] This invention discloses a method for controlling pine caterpillars in Pinus sylvestris. It utilizes a combination of biological and physical methods to control pine caterpillar pests. By preparing a multi-layered pine caterpillar control agent, Beauveria bassiana spores are loaded onto liposomes and then mixed with a hydrogel. This method protects the activity of Beauveria bassiana spores while promoting the infection of pine caterpillars by Beauveria bassiana, thus solving the problem of unstable control effect of Beauveria bassiana due to environmental influences, thereby achieving a stable and good control effect. Attached Figure Description

[0032] Figure 1 Investigation on the pine caterpillar infestation of Pinus sylvestris; Detailed Implementation

[0033] The present invention will be described in detail below with reference to specific embodiments:

[0034] Example 1: Preparation of a pine caterpillar control agent

[0035] S1: Add 1g of Beauveria bassiana spore powder containing 30 billion spores / g and 0.1g of Tween 80 to 100ml of PBS solution with pH=6.8 and stir well; dissolve 1.5g of soybean lecithin and 0.5g of cholesterol in 20ml of anhydrous ethanol, and rotary evaporate at 45℃ for 30min to obtain a lipid membrane. Mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder and treat it in an ice-water bath at an ultrasonic frequency of 25kHz for 10min to obtain a liposome suspension.

[0036] S2: Dissolve 50g of acrylic acid in 50g of water to prepare an acrylic acid solution. Add 30wt% sodium hydroxide solution to the acrylic acid solution to adjust the pH to 6.8. Then add 5g of glycerol, 1g of ammonium persulfate and 1g of N,N-methylenebisacrylamide. Stir well and let stand for 1h. Then add 50g of liposome suspension and stir well. Let stand for 2h to obtain sodium polyacrylate gel. Freeze-dry the sodium polyacrylate gel at 10pa and -40℃ for 24h and then pulverize it into sodium polyacrylate gel particles with a particle size of 1mm.

[0037] S3: Add 0.4g of diatomaceous earth to 2g of water, sonicate for 20min to disperse evenly, then add to 100g of 2wt% sodium alginate solution and stir evenly to obtain sodium alginate mixed solution. Spray 10g of sodium alginate mixed solution onto the surface of 100g of sodium polyacrylate gel particles, then spray 5g of 2.5wt% calcium chloride solution, let stand for cross-linking for 40min, dry at 30℃ for 1h, and then crush into composite gel particles with a particle size of 1.5mm.

[0038] S4: Dissolve 1g xanthan gum in 67g water, then add 2g sodium lignosulfonate and 20g composite gel particles, and stir well to obtain a stable suspension pine caterpillar control agent.

[0039] Example 2: Preparation of a pine caterpillar control agent

[0040] S1: Add 1g of Beauveria bassiana spore powder containing 30 billion spores / g and 0.1g of Tween 80 to 100ml of PBS solution with pH=6.8 and stir well; dissolve 1.5g of soybean lecithin and 0.5g of cholesterol in 20ml of anhydrous ethanol, and rotary evaporate at 45℃ for 30min to obtain a lipid membrane. Mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder and treat it in an ice-water bath at an ultrasonic frequency of 25kHz for 10min to obtain a liposome suspension.

[0041] S2: Dissolve 55g of acrylic acid in 55g of water to prepare an acrylic acid solution. Add 30wt% sodium hydroxide solution to the acrylic acid solution to adjust the pH to 7.2. Then add 6g of glycerol, 1.2g of ammonium persulfate and 1.2g of N,N-methylenebisacrylamide. Stir well and let stand for 1h. Then add 55g of liposome suspension and stir well. Let stand for 3h to obtain sodium polyacrylate gel. Freeze-dry the sodium polyacrylate gel at 10pa and -40℃ for 24h and then pulverize it into sodium polyacrylate gel particles with a particle size of 2mm.

[0042] S3: Add 0.5g of diatomaceous earth to 2.5g of water, sonicate for 20min to disperse evenly, then add 150g of 2.5wt% sodium alginate solution and stir evenly to obtain sodium alginate mixed solution. Spray 10g of sodium alginate mixed solution onto the surface of 100g of sodium polyacrylate gel particles, then spray 5g of 3wt% calcium chloride solution, let stand for cross-linking for 30min, dry at 40℃ for 1h, and then crush into composite gel particles with a particle size of 2mm.

[0043] S4: Dissolve 0.5g xanthan gum in 63g water, then add 1.5g sodium lignosulfonate and 25g composite gel particles, and stir well to obtain a stable suspension pine caterpillar control agent.

[0044] Example 3: Control of pine caterpillars

[0045] (1) Control of overwintering generations: In mid-January, within a radius of 50cm on the trunk, use tools to turn over the dead branches and fallen leaves to expose the pine caterpillars that are overwintering underground.

[0046] (2) Control during the tree-planting period: In mid-April, scrape off the old bark that is easy to fall off at a position 1m above the ground on the trunk, brush a circle of pine caterpillar control agent around the trunk with a soft brush, and then spray water to moisten it. The width of the application is 10cm, the amount of application is 40g / tree, and the amount of water sprayed is 25g / tree.

[0047] (3) Adult insect control: From July to August, a black light trapping device is set up in the central tree of each group, with a hanging height of 1.5m. The light is turned on at 19:30 every day and turned off at 5:30 the next morning.

[0048] (4) Control during the tree fall period: In early November, scrape off the old bark that is easy to fall off at a position 1m above the ground on the trunk, brush a circle of pine caterpillar control agent around the trunk with a soft brush, and then spray water to moisten it. The application width is 10cm, the application amount is 40g / tree, and the water spray amount is 25g / tree.

[0049] Comparative Example 1: Preparation of a Pine Caterpillar Control Agent

[0050] Compared with Example 1, the only difference is that Beauveria bassiana spore powder was directly prepared into a pine caterpillar control agent. The specific preparation method is as follows:

[0051] Dissolve 1g of xanthan gum in 67g of water, then add 2g of sodium lignosulfonate and 0.2g of Beauveria bassiana spore powder, and stir well to obtain a stable suspension pine caterpillar control agent.

[0052] Comparative Example 2: Preparation of Pine Caterpillar Control Agent

[0053] Compared with Example 1, the only difference is that Beauveria bassiana was not loaded with liposomes; instead, Beauveria bassiana spore powder was directly added to sodium polyacrylate gel. The specific preparation method is as follows:

[0054] S1: Dissolve 50g of acrylic acid in 50g of water to prepare an acrylic acid solution. Add 30wt% sodium hydroxide solution to the acrylic acid solution to adjust the pH to 6.8. Then add 5g of glycerol, 1g of ammonium persulfate and 1g of N,N-methylenebisacrylamide. Stir well and let stand for 1h. Then add 0.5g of Beauveria bassiana spore powder and stir well. Let stand for 2h to obtain sodium polyacrylate gel. Freeze-dry the sodium polyacrylate gel at 10pa and -40℃ for 24h and then pulverize it into sodium polyacrylate gel particles with a particle size of 1mm.

[0055] The subsequent process of preparing sodium polyacrylate gel particles into composite gel particles and then into pine caterpillar control agents is the same as steps S3 and S4 in Example 1.

[0056] Comparative Example 3: Preparation of Pine Caterpillar Control Agent

[0057] Compared with Example 1, the only difference is that the sodium polyacrylate gel particles are not sprayed with a sodium alginate mixed solution. The specific preparation method is as follows:

[0058] S1: Add 1g of Beauveria bassiana spore powder containing 30 billion spores / g and 0.1g of Tween 80 to 100ml of PBS solution with pH=6.8 and stir well; dissolve 1.5g of soybean lecithin and 0.5g of cholesterol in 20ml of anhydrous ethanol, and rotary evaporate at 45℃ for 30min to obtain a lipid membrane. Mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder and treat it in an ice-water bath at an ultrasonic frequency of 25kHz for 10min to obtain a liposome suspension.

[0059] S2: Dissolve 50g of acrylic acid in 50g of water to prepare an acrylic acid solution. Add 30wt% sodium hydroxide solution to the acrylic acid solution to adjust the pH to 6.8. Then add 5g of glycerol, 1g of ammonium persulfate and 1g of N,N-methylenebisacrylamide. Stir well and let stand for 1h. Then add 50g of liposome suspension and stir well. Let stand for 2h to obtain sodium polyacrylate gel. Freeze-dry the sodium polyacrylate gel at 10pa and -40℃ for 24h and then pulverize it into sodium polyacrylate gel particles with a particle size of 1mm.

[0060] S3: Dissolve 1g xanthan gum in 67g water, then add 2g sodium lignosulfonate and 20g sodium polyacrylate gel particles, and stir well to obtain a stable suspension pine caterpillar control agent.

[0061] Comparative Example 4: Preparation of Pine Caterpillar Control Agent

[0062] Compared with Example 1, the only difference is that diatomaceous earth is not added to the sodium alginate solution. The specific preparation method is as follows:

[0063] S1: Add 1g of Beauveria bassiana spore powder containing 30 billion spores / g and 0.1g of Tween 80 to 100ml of PBS solution with pH=6.8 and stir well; dissolve 1.5g of soybean lecithin and 0.5g of cholesterol in 20ml of anhydrous ethanol, and rotary evaporate at 45℃ for 30min to obtain a lipid membrane. Mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder and treat it in an ice-water bath at an ultrasonic frequency of 25kHz for 10min to obtain a liposome suspension.

[0064] S2: Dissolve 50g of acrylic acid in 50g of water to prepare an acrylic acid solution. Add 30wt% sodium hydroxide solution to the acrylic acid solution to adjust the pH to 6.8. Then add 5g of glycerol, 1g of ammonium persulfate and 1g of N,N-methylenebisacrylamide. Stir well and let stand for 1h. Then add 50g of liposome suspension and stir well. Let stand for 2h to obtain sodium polyacrylate gel. Freeze-dry the sodium polyacrylate gel at 10pa and -40℃ for 24h and then pulverize it into sodium polyacrylate gel particles with a particle size of 1mm.

[0065] S3: Spray 10g of 2wt% sodium alginate solution onto the surface of 100g of sodium polyacrylate gel particles, then spray 5g of 2.5wt% calcium chloride solution, let stand for cross-linking for 40min, dry at 30℃ for 1h, and then crush into composite gel particles with a particle size of 1.5mm.

[0066] S4: Dissolve 1g xanthan gum in 67g water, then add 2g sodium lignosulfonate and 20g composite gel particles, and stir well to obtain a stable suspension pine caterpillar control agent.

[0067] Comparative Example 5: Preparation of a Pine Caterpillar Control Agent

[0068] Compared with Example 1, the only difference is that the liposome suspension was directly mixed with sodium alginate solution to prepare composite gel particles. The specific preparation method is as follows:

[0069] S1: Add 1g of Beauveria bassiana spore powder containing 30 billion spores / g and 0.1g of Tween 80 to 100ml of PBS solution with pH=6.8 and stir well; dissolve 1.5g of soybean lecithin and 0.5g of cholesterol in 20ml of anhydrous ethanol, and rotary evaporate at 45℃ for 30min to obtain a lipid membrane. Mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder and treat it in an ice-water bath at an ultrasonic frequency of 25kHz for 10min to obtain a liposome suspension.

[0070] S2: Add 0.4g of diatomaceous earth to 2g of water, sonicate for 20min to disperse evenly, then add to 100g of 2wt% sodium alginate solution and stir evenly. Then add 50g of liposome suspension, stir evenly, and drop into 2.5wt% calcium chloride solution to form gel particles. After filtration, freeze dry at 10pa and -40℃ for 24h, and then pulverize into composite gel particles with a particle size of 1.5mm.

[0071] S3: Dissolve 1g xanthan gum in 67g water, then add 2g sodium lignosulfonate and 20g composite gel particles, and stir well to obtain a stable suspension pine caterpillar control agent.

[0072] Comparative Example 6: Preparation of Pine Caterpillar Control Agent

[0073] Compared with Example 1, the only difference is the increased amount of acrylic acid. The specific preparation method is as follows:

[0074] S1: Add 1g of Beauveria bassiana spore powder containing 30 billion spores / g and 0.1g of Tween 80 to 100ml of PBS solution with pH=6.8 and stir well; dissolve 1.5g of soybean lecithin and 0.5g of cholesterol in 20ml of anhydrous ethanol, and rotary evaporate at 45℃ for 30min to obtain a lipid membrane. Mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder and treat it in an ice-water bath at an ultrasonic frequency of 25kHz for 10min to obtain a liposome suspension.

[0075] S2: Dissolve 70g of acrylic acid in 50g of water to prepare an acrylic acid solution. Add 30wt% sodium hydroxide solution to the acrylic acid solution to adjust the pH to 6.8. Then add 5g of glycerol, 1g of ammonium persulfate and 1g of N,N-methylenebisacrylamide. Stir well and let stand for 1h. Then add 50g of liposome suspension and stir well. Let stand for 2h to obtain sodium polyacrylate gel. Freeze-dry the sodium polyacrylate gel at 10pa and -40℃ for 24h and then pulverize it into sodium polyacrylate gel particles with a particle size of 1mm.

[0076] The subsequent process of preparing sodium polyacrylate gel particles into composite gel particles and then into pine caterpillar control agents is the same as steps S3 and S4 in Example 1.

[0077] Comparative Example 7: Preparation of Pine Caterpillar Control Agent

[0078] Compared with Example 1, the only difference is the increased concentration of sodium alginate solution. The specific preparation method is as follows:

[0079] S1: Add 1g of Beauveria bassiana spore powder containing 30 billion spores / g and 0.1g of Tween 80 to 100ml of PBS solution with pH=6.8 and stir well; dissolve 1.5g of soybean lecithin and 0.5g of cholesterol in 20ml of anhydrous ethanol, and rotary evaporate at 45℃ for 30min to obtain a lipid membrane. Mix the lipid membrane with PBS solution containing Beauveria bassiana spore powder and treat it in an ice-water bath at an ultrasonic frequency of 25kHz for 10min to obtain a liposome suspension.

[0080] S2: Dissolve 50g of acrylic acid in 50g of water to prepare an acrylic acid solution. Add 30wt% sodium hydroxide solution to the acrylic acid solution to adjust the pH to 6.8. Then add 5g of glycerol, 1g of ammonium persulfate and 1g of N,N-methylenebisacrylamide. Stir well and let stand for 1h. Then add 50g of liposome suspension and stir well. Let stand for 2h to obtain sodium polyacrylate gel. Freeze-dry the sodium polyacrylate gel at 10pa and -40℃ for 24h and then pulverize it into sodium polyacrylate gel particles with a particle size of 1mm.

[0081] S3: Add 0.4g of diatomaceous earth to 2g of water, sonicate for 20min to disperse evenly, then add to 100g of 3.5wt% sodium alginate solution and stir evenly to obtain sodium alginate mixed solution. Spray 10g of sodium alginate mixed solution onto the surface of 100g of sodium polyacrylate gel particles, then spray 5g of 2.5wt% calcium chloride solution, let stand for cross-linking for 40min, dry at 30℃ for 1h, and then crush into composite gel particles with a particle size of 1.5mm.

[0082] S4: Dissolve 1g xanthan gum in 67g water, then add 2g sodium lignosulfonate and 20g composite gel particles, and stir well to obtain a stable suspension pine caterpillar control agent.

[0083] The remaining preparation steps S1, S2, and S4 are the same as in Example 1.

[0084] Experiment 1: Prevention and Control Experiment

[0085] 1. Place a 10cm×20cm×10cm transparent incubator at a concentration of 0.1g / cm 2 Apply a layer of pine caterpillar control agent evenly to the bottom and sides of the container, and spray 30g of water evenly to moisten the surface of the control agent. This container is designated as a normal incubator. Then, place the normal incubator that has undergone the above operation outdoors under natural temperature / humidity and no direct sunlight for 3 days. This container is designated as a treatment incubator. The incubators of the blank control group are not treated.

[0086] 2. Experimental Group 1: The pine caterpillar control agent prepared in Example 1 was applied to the incubator; Control Groups 1-7 were applied to the incubators with the pine caterpillar control agents prepared in Comparative Examples 1-7, respectively.

[0087] 3. Forty 3rd-4th instar larch caterpillar larvae were taken from each group. After free feeding, 20 larvae were randomly selected and placed in a regular incubator, and the remaining 20 larvae were placed in a treatment incubator. The control experiment was carried out under the conditions of incubation temperature of 25±1℃, relative humidity of 90%, light intensity of 1500lx, and light duration of 12h / d.

[0088] 4. After 2 days of cultivation, a layer of fresh pine needles was added. The pine needles were replaced every 2 days, and each treatment was repeated 5 times per group. The mortality rate was recorded after 3, 5, 7, and 10 days of cultivation, and the results are shown in Table 1.

[0089] Experiment 2:

[0090] In April 2023, the population density of pine caterpillars in the *Pinus sylvestris* planting area of ​​the Yuyang District Botanical Garden in Yulin City, Shaanxi Province, was 49 caterpillars per tree, indicating moderate damage. In January 2024, a pine caterpillar control experiment was conducted in the *Pinus sylvestris* planting area of ​​the Yuyang District Botanical Garden in Yulin City, Shaanxi Province, with three adjacent *Pinus sylvestris* trees randomly selected from each group. The distance between each group was more than 10 meters, and each group was replicated three times.

[0091] Pine caterpillar control:

[0092] (1) Control of overwintering larvae: On January 15, within a radius of 50cm of the tree trunk, use tools to turn over the dead branches and fallen leaves to expose the pine caterpillar larvae that are overwintering underground.

[0093] (2) Control during the tree-planting period: On April 13, scrape off the old bark that is easy to fall off at a position 1m above the ground on the trunk, brush a circle of pine caterpillar control agent around the trunk with a soft brush, and then spray water to moisten it. The width of the application is 10cm, the amount of application is 40g / tree, and the amount of water sprayed is 25g / tree.

[0094] (3) Adult insect control: On July 5, a black light trapping device was set up in the central tree of each group, with a hanging height of 1.5m. The light was turned on at 19:30 every day and turned off at 5:30 the next morning. The device was taken down on August 25.

[0095] (4) Control during the tree fall period: On November 5, scrape off the old bark that is easy to fall off at a position 1m above the ground on the trunk, brush a circle of pine caterpillar control agent around the trunk with a soft brush, and then spray water to moisten it. The application width is 10cm, the application amount is 40g / tree, and the water spray amount is 25g / tree.

[0096] The average insect population density of each group of Pinus sylvestris before tree planting and control was counted on April 10, 2024; the average insect population density of each group of Pinus sylvestris before adult insect control was counted on July 1, 2024; and the average insect population density of each group of Pinus sylvestris before tree planting was counted on April 10, 2025. The statistical results are shown in Table 2.

[0097] Experimental group 1 used the pine caterpillar control agent prepared in Example 1; control groups 1-7 used the pine caterpillar control agents prepared in Comparative Examples 1-7 respectively; control group 8 used the pine caterpillar control agent prepared in Example 1, without spraying water to moisten it after application; control group 9 used the pine caterpillar control agent prepared in Example 1, with a water spray amount of 50g / plant after application; control group 10 used water as the control agent. The blank control group did not receive any control treatment.

[0098] Mortality rate = (Number of dead insects / Total number of insects) × 100%;

[0099] Table 1 Mortality Rate

[0100]

[0101] Table 2 Average insect population density (insects / plant)

[0102]

[0103]

[0104] Analysis of the data in Tables 1 and 2 shows that:

[0105] 1. Compared to the experimental group, the control agent used in control group 1, which directly prepared Beauveria bassiana spores into a suspension, resulted in a high mortality rate for pine caterpillars in ordinary incubators, but a significantly lower mortality rate in the treated incubators. In the forest trial, control group 1 showed poorer control efficacy and a smaller decrease in average caterpillar density. This is because Beauveria bassiana is easily inactivated by ultraviolet radiation in the natural environment, and its germination requires high humidity. In control group 1, after the control agent was applied to the incubator and left outdoors for 3 days, the Beauveria bassiana in the suspension was directly affected by natural light, reducing its activity and thus lowering the mortality rate of pine caterpillars. In the forest trial, in addition to the influence of light, the humidity conditions were insufficient to meet the germination requirements of Beauveria bassiana, resulting in a slower germination rate. The slow reaction time leads to poor control of pine caterpillars. In experimental group 1, Beauveria bassiana was loaded with liposomes and mixed into a hydrogel, then coated with a layer of calcium alginate film embedded with diatomaceous earth to protect the Beauveria bassiana from inactivation by the external environment. After contact with pine caterpillars, the sodium polyacrylate gel mixed with liposomes was exposed. The liposomes fused with the pine caterpillar epidermis, promoting the infection of pine caterpillars by Beauveria bassiana. At the same time, Beauveria bassiana could germinate rapidly by utilizing the water in the pine caterpillars and the gel, improving the infection efficiency of Beauveria bassiana. This allowed Beauveria bassiana to maintain a stable and efficient insecticidal effect when used in the natural environment, thereby effectively reducing the number of pine caterpillars, reducing their further reproduction, and reducing the number of caterpillars the following year, thus achieving a good control effect.

[0106] 2. Compared with experimental group 1, the pine caterpillar control agent used in control group 2 did not use liposome-loaded Beauveria bassiana. Instead, Beauveria bassiana spore powder was directly mixed with water-absorbing gel to form gel particles. The mortality rate of pine caterpillars was high in ordinary incubators, but decreased in treated incubators. In the forest trial, the control effect of control group 2 was reduced. This is because Beauveria bassiana directly contacted the water-absorbing gel. Before contacting the pine caterpillars, some Beauveria bassiana absorbed the water in the gel and germinated prematurely, losing their infectivity. After contacting the pine caterpillars, the infection rate decreased, which in turn led to a decrease in the mortality rate of pine caterpillars and a decline in the control effect.

[0107] 3. Compared with experimental group 1, the sodium polyacrylate gel surface of the pine caterpillar control agent used in control group 3 was not covered with a calcium alginate film. The mortality rate of pine caterpillars was high in ordinary incubators, but decreased in treated incubators. In the forest trial, the control effect of control group 3 was reduced. This is because without the protection of the outer calcium alginate film, Beauveria bassiana was more susceptible to environmental influences and its activity decreased, resulting in a lower mortality rate and control effect of pine caterpillars. In addition, when used in the forest, the gel mixed with Beauveria bassiana was directly exposed to the natural environment, which could easily infect other beneficial insects such as Trichogramma wasps. The calcium alginate film surface of the pine caterpillar control agent used in control group 4 did not contain diatomite. When used in incubators, the onset time was slower, and the control effect was reduced in the forest trial. This is because the calcium alginate film surface did not contain diatomite, the water permeability of the calcium alginate film was reduced, the expansion of sodium polyacrylate was slower, and the surface roughness of the calcium alginate film was reduced, resulting in less friction with pine caterpillars. As a result, when pine caterpillars came into contact with the control agent, the calcium alginate film could not be broken in time to release Beauveria bassiana and infect the pine caterpillars.

[0108] 4. Compared with experimental group 1, the pine caterpillar control agent used in control group 5 was prepared by directly mixing Beauveria bassiana-loaded liposome particles with sodium alginate to form gel particles, without using sodium polyacrylate gel. When used in the incubator, the onset time was slower and the mortality rate of pine caterpillars was lower. However, the control effect was reduced in the forest experiment. This is because the sodium alginate gel absorbs water and swells slowly, has a strong slow-release effect, and cannot release Beauveria bassiana infection in time when it comes into contact with pine caterpillars, resulting in a slower onset time and reduced control effect. The pine caterpillar control agent used in control group 6 had an increased acrylic monomer content when preparing the sodium polyacrylate gel. It was effective when used in the incubator, but the control effect was reduced in the forest experiment. This is because the increased acrylic monomer content resulted in a higher degree of cross-linking of the prepared sodium polyacrylate gel, which reduced its adhesiveness after absorbing water and swelling. When used in the forest, it could not adhere to the pine caterpillars continuously, the contact time between the control agent and the pine caterpillars was shorter, the Beauveria bassiana infection rate decreased, and the control effect was reduced.

[0109] 5. Compared with experimental group 1, the sodium alginate solution concentration in the pine caterpillar control agent used in control group 7 was higher. When used in the incubator, the onset time was slower, the mortality rate of pine caterpillars was lower, and the control effect was reduced in the forest experiment. This is because the increased concentration of sodium alginate solution increased the strength of the calcium alginate film formed with calcium chloride, making it more difficult for the composite gel particles to break. When in contact with pine caterpillars, Beauveria bassiana in the inner gel could not be released in time, resulting in a slower onset time, a lower mortality rate of pine caterpillars, and a reduced control effect.

[0110] 6. Compared with experimental group 1, the amount of water sprayed after applying the pine caterpillar control agent differed between control groups 8 and 9. In control group 8, no water was sprayed after applying the pine caterpillar control agent. The gel in the paper towel could not absorb enough water to swell in the natural environment, resulting in the inability to release Beauveria bassiana to infect the pine caterpillars in time when in contact with them, leading to poor control effect. In control group 9, excessive water was sprayed after applying the pine caterpillar control agent. The composite gel particles in the control agent absorbed too much water and swelled and ruptured directly. Beauveria bassiana was exposed to the natural environment and its activity was reduced due to environmental influences, thus leading to a decrease in control effect.

[0111] 7. Control group 10 used water as the control agent, without biological control, and the purely physical method was not effective in controlling pine caterpillars.

[0112] 8. No control measures were taken in the control group, and the pest situation in the forest worsened.

[0113] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A method for controlling pine caterpillars in Pinus sylvestris, characterized in that, The method is as follows: (1) Control of overwintering generation: Turn over the dead branches and fallen leaves around the trunk to expose the pine caterpillars that are overwintering underground, thereby reducing the number of overwintering pine caterpillars. (2) Control during the tree climbing period: After brushing the pine caterpillar control agent onto the trunk of the Pinus sylvestris tree, spray water to moisten it and kill the larvae climbing the tree; (3) Adult control: Use black light traps to capture adult pine caterpillars to reduce their reproduction and lower the number of insects in the following year; (4) Control during the fall period: After brushing the pine caterpillar control agent onto the trunk of the Pinus sylvestris tree, spray water to moisten it and kill the larvae that fall from the tree; The preparation method of the pine caterpillar control agent is as follows: S1: Add Beauveria bassiana spore powder and Tween 80 to a PBS solution with pH=6.8 and stir well; dissolve soybean lecithin and cholesterol in anhydrous ethanol and rotary evaporate at 45℃ for 30-40 min to obtain a lipid membrane; mix the lipid membrane with a PBS solution containing Beauveria bassiana spore powder to obtain a liposome suspension. S2: Acrylic acid is dissolved in water to prepare an acrylic acid solution. 30wt% sodium hydroxide solution is added to the acrylic acid solution to adjust the pH to 6.8-7.

2. Then glycerol, ammonium persulfate and N,N-methylenebisacrylamide are added. After stirring evenly, the mixture is allowed to stand for 1 hour. Then liposome suspension is added and stirred evenly. After standing for 2-3 hours, sodium polyacrylate gel is obtained. The sodium polyacrylate gel is freeze-dried and then pulverized to obtain sodium polyacrylate gel particles. S3: Add diatomaceous earth to water, sonicate for 20-30 minutes, then add 2-2.5 wt% sodium alginate solution and stir evenly to obtain sodium alginate mixed solution. Spray the sodium alginate mixed solution onto the surface of sodium polyacrylate gel particles, then spray 2.5-3 wt% calcium chloride solution, let stand for cross-linking for 30-40 minutes, dry at 30-40℃, and then pulverize to obtain composite gel particles; S4: Dissolve xanthan gum in water, then add sodium lignosulfonate and composite gel particles, and stir evenly to obtain a stable suspension pine caterpillar control agent.

2. The method for controlling pine caterpillars of Pinus sylvestris according to claim 1, characterized in that, The method of application for the pine caterpillar control agent is as follows: Apply the pine caterpillar control agent to the trunk 1-1.2m above the ground, forming a closed ring 8-10cm wide. The application amount is 30-40g per tree, and the water spray amount is 20-25g per tree.

3. The method for controlling pine caterpillars of Pinus sylvestris according to claim 2, characterized in that, The overwintering generation control is carried out in January, the tree-planting control is carried out in mid-April, the adult insect control is carried out in July-August, and the tree-down control is carried out in November.

4. The method for controlling pine caterpillars of Pinus sylvestris according to claim 3, characterized in that, The Beauveria bassiana spore powder contains 30 billion spores / gram; the mass ratio of the Beauveria bassiana spore powder, Tween 80, and PBS solution is 1:0.1:100; the mass ratio of soybean lecithin:cholesterol:Beauveria bassiana spore powder is 3:1:

2.

5. The method for controlling pine caterpillars of Pinus sylvestris according to claim 4, characterized in that, The mass ratio of the acrylic acid, glycerol, ammonium persulfate, N,N-methylenebisacrylamide, and liposome suspension is (50-55):(5-6):(1-1.2):(1-1.2):(50-55).

6. The method for controlling pine caterpillars of Pinus sylvestris according to claim 5, characterized in that, The freeze-drying conditions were: maintaining a pressure of 10 Pa, a cold trap temperature of -40 °C, and freeze-drying for 24 hours.

7. The method for controlling pine caterpillars of Pinus sylvestris according to claim 6, characterized in that, The sodium polyacrylate gel particles have a particle size of 1-2 mm, and the composite gel particles have a particle size of 1.5-2 mm.

8. The method for controlling pine caterpillars of Pinus sylvestris according to claim 7, characterized in that, The mass ratio of diatomaceous earth to sodium alginate solution is 1:(250-300); the mass ratio of sodium alginate mixed solution to sodium polyacrylate gel particles is 1:10; and the mass ratio of sodium alginate mixed solution to calcium chloride solution is 2:

1.

9. The method for controlling pine caterpillars of Pinus sylvestris according to claim 8, characterized in that, The raw materials of the pine caterpillar control agent are as follows by weight percentage: xanthan gum 0.5-1%, sodium lignosulfonate 1.5-2%, composite gel particles 20-25%, and the remainder is water.

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