Application of cinnamomum longepaniculatum essential oil in prevention and control of stored grain

Abstract

The invention discloses application of cinnamomum longepaniculatum essential oil in prevention and control of stored grain pests, and relates to the technical field of stored grain pest prevention and control. According to the method disclosed by the invention, the fumigation, contact toxicity and avoidance effects of the cinnamomum longepaniculatum crude oil, the cinnamomum longepaniculatum residual oil light components obtained after extraction and processing of the cinnamomum longepaniculatum crude oil, alpha-terpilenol and 1, 8-cineole on rice weevil and tribolium castaneum adults are analyzed by utilizing indoor toxicity determination; changes of the essential oil alpha-terpilenol with the best effect on activity of protective enzyme, detoxification enzyme and digestive enzyme in the two stored grain pests are determined, and a reference basis is provided for preventing and controlling rice weevil and tribolium cavaleriei by scientifically and reasonably using the cinnamomum longepaniculatum essential oil. The alpha-terpilenol can be used as a potential biopesticide for rice weevil and tribolium cavaleriei, and lays a theoretical foundation for molecular research and green prevention and control of stored grain pests. The invention effectively solves the problems of pest resistance, public health and safety and environmental pollution easily caused by a chemical control strategy.

Description

Technical Field

[0001] The invention relates to the technical field of stored-grain pest control, and in particular to application of camphor essential oil in controlling stored-grain pests. Background Art

[0002] Biological (insects, mites, rodents and fungi) and abiotic (temperature, humidity) factors are the main reasons for the loss rate of grain exceeding 60%. In particular, the annual loss rate caused by stored grain pests during the grain storage period is about 1%, which not only reduces the germination ability of grains, but also directly or indirectly causes the reduction of grain quality and nutritional value, thus threatening global food security and causing serious economic losses. Rice weevils (Sitophilus oryzae; Linnaeus, Coleoptera: Curculionidae) and red flour beetles (Tribolium castaneum; Herbst, Coleooptra: Tenebrionidae) are the two most widely distributed and most destructive stored grain pests, which can damage various grains and their processed products, medicinal materials, dried fruits and animal products, etc., causing grains to have a musty smell and a high insect-eaten grain rate. For example, the weight loss of sorghum after damage can reach 4.59%. For a long time, chemical control strategies have been mainly used for the prevention and management of stored-grain pests, which can easily cause problems such as pest resistance, public health and safety, and environmental pollution. Therefore, there is an urgent need to develop green control, environmentally sustainable and effective eco-friendly alternatives, which are of far-reaching significance for maintaining food quality and quantity. In recent years, research on plant essential oils as natural medicines has attracted more and more attention. It is a small molecule fat-soluble substance composed of different biologically active compounds. Plant essential oils can play a role in pest control through contact killing, repellent, fumigation and oviposition inhibition. The insect repellent and antibacterial active substances contained in essential oils have strong penetration ability and can exert insecticidal effects by destroying the body wall tissue of pests and dissolving the wax layer. They can also stimulate insect receptors to interfere with their biological behavior, and inhibit the metabolic enzyme function in insects to weaken the degradation efficiency of insecticides. Many studies have shown that plant essential oils have great potential in the prevention and control of stored-grain pests. Therefore, plant essential oils can be developed as safe and low-toxic contact killers, fumigants and repellents to obtain efficient and green control agents.

[0003] Cinnamomum longepaniculatum (Gamble) N. Chao is a precious tree species of the Lauraceae family. Yibin City is the largest producer of camphor oil in China. The oil content of its leaves (3.8%-4.5%) is nearly three times that of other regions. Cinnamomum longepaniculatum essential oil obtained by steam distillation is a colorless or light yellow liquid. Its main components are 1,8-cineole, α-terpineol, sabinene, etc. It has antibacterial, antioxidant, and anti-inflammatory effects. Cinnamomum longepaniculatum (Gamble) N. Chao is the residue after crude oil processing. It can be divided into light components and heavy components according to density, but the actual utilization is blank. A large amount of stacking causes waste of resources. It is of great significance to improve the recycling of resources by increasing the research on residual oil. At present, there is no research report on the use of Cinnamomum longepaniculatum essential oil, especially the light components of Cinnamomum longepaniculatum residual oil, in pest control. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides an application of camphor essential oil in controlling stored-grain pests, laying a theoretical foundation for molecular-level research and green control of stored-grain pests, and effectively solving the problem that chemical control strategies are prone to cause pest resistance, public health and safety, and environmental pollution.

[0005] To achieve the above object, the technical solution adopted by the present invention to solve the technical problem is: application of camphor essential oil in any one of the following (1)-(4):

[0006] (1) Control of stored grain pests;

[0007] (2) Preparation of products for controlling stored-grain pests;

[0008] (3) disrupting the normal physiological and metabolic activities of stored-grain pests;

[0009] (4) Preparing products that disrupt the normal physiological and metabolic activities of stored-grain pests.

[0010] Furthermore, the camphor essential oil is at least one of camphor crude oil, camphor residual oil light components, α-pineneol and 1,8-cineole.

[0011] Furthermore, the camphor essential oil is α-terpineol.

[0012] Furthermore, the crude oil of camphor tree is prepared from camphor tree leaves by steam distillation.

[0013] Furthermore, the preparation method of camphor crude oil includes the following steps: crushing camphor leaves, mixing them at a material-water ratio of 1:10 (g / mL), adding them into an extraction kettle, steaming at 105-110°C for 2h, collecting the upper oily liquid of the distillate and removing residual water with an oil separator to obtain camphor crude oil.

[0014] Furthermore, the above camphor oil residue light component is prepared by the following method:

[0015] S1. Separate and collect cineole, eucalyptus oil, terpineol, α-terpineol, camphor, β-caryophyllene, white camphor oil, γ-terpineol, terpinene-4-ol, terpinene, α-pinene, δ-terpineol, β-phellandrene, myrcene, butyl-terpineol and propyl-terpinene from the crude camphor oil by distillation and freeze-crystallization separation and purification technology to obtain camphor oil residual oil;

[0016] S2. Separating the camphor oil residue obtained in step S1 by vacuum distillation technology to obtain a light component of the camphor oil residue.

[0017] Furthermore, in step S2, during vacuum distillation, the vacuum degree of the tower top is 96-98, the vacuum degree of the tower bottom is 89-91, and the temperature of the tower bottom is 155-168°C.

[0018] Further, in step S2, the density of the light component of the camphor oil residue is 0.8-0.9 g / cm 3 .

[0019] Furthermore, the stored-grain pests are rice weevils and / or red flour beetles.

[0020] Furthermore, the contact killing concentration of camphor essential oil is 0.01-0.42 μL / cm 2 The fumigation concentration of camphor essential oil is 6-42μL / L air.

[0021] In summary, the present invention has the following beneficial effects:

[0022] 1. Plant essential oil is a volatile plant secondary metabolite with a characteristic fragrance extracted from aromatic plants. It is rich in active ingredients such as aromatic phenols, aldehydes, alcohols, ketones and esters, and has antibacterial and insecticidal activity. Plant essential oil mainly uses its lipophilicity to contact the surface of insects, destroys the body wall structure and dissolves the cuticle, promotes the penetration of essential oil components into the body, and plays a role. The fumigation activity usually reaches the inside with the help of the respiratory and digestive systems. The avoidance activity mainly stimulates the insect receptors and interferes with its biological behavior. Some components can block specific neurotransmitters and kill pests. In the present invention, the repellent effect of camphor oil crude oil, camphor oil residual oil light component, α-pineneol and 1,8-cineole on 2 target pests at 2 time points is analyzed. It can be seen that when the 2h high concentration effect is extended to 4h, the repellency rate of α-pineneol to rice weevils and residual oil and 1,8-cineole to red flour beetles is on a downward trend, indicating that these agents have poor persistence in the repellent effect of corresponding pests and a long effective time. Cinnamon bark oil and α-terpineol have strong repellent activity against red flour beetle at high concentrations (repellent rate>80%). Cinnamon bark oil residue and camphor oil have good repellent activity against rice weevil and red flour beetle, respectively, but weak effect on the other pest, which may be the result of synergistic and antagonistic effects between the components, or physiological, biochemical and morphological differences of insects. It also shows that the repellent activity of the four essential oils to rice weevil is concentration-dependent, and 1,8-cineole and α-terpineol are time-dependent to rice weevil and red flour beetle, respectively.

[0023] 2. The present invention explores the effect of α-terpineol on protective enzymes, detoxifying enzymes and digestive enzymes in pests through fumigation. POD, CAT and SOD are important antioxidant enzymes in insects. Due to the accumulation of a large amount of reactive oxygen species such as superoxide anion radicals, hydroxyl radicals and hydrogen peroxide in insects under adverse stress, free radical toxicity is triggered, and the protective enzyme system in insects can play a protective role, and the three work together to maintain the dynamic stability level of free radical content. At the same time, the invasion of toxic substances can stimulate the defense response of protective enzymes in insects. In the embodiments provided by the present invention, with the increase of essential oil treatment concentration and treatment time, hydrogen peroxide in rice weevils and red flour beetles increases significantly, and hydrogen peroxide is decomposed by inducing POD activity to reduce its oxidative damage to the body, and POD is the main protective enzyme to alleviate α-terpineol stress. The dynamic balance of the protective enzyme system in the pest body is broken by α-terpineol to produce toxicity, and the generation and removal of free radicals are unbalanced, resulting in the death of insects. At the same time, in the face of external adverse stress, the defensive stress generated by insects continues to exceed a certain intensity, and the pests cannot adapt to stress damage and cause death.

[0024] 3. Carboxylesterase (CES), acetylcholinesterase (AChE), glutathione S-transferase (GST), cytochrome P450 enzyme system (CYP450) and mixed function oxidase (MFO) are important detoxification enzymes in insects. They play an important role in decomposing exogenous toxins, maintaining insect resistance and physiological metabolism, and catalyzing the excretion of harmful molecules. Among them, CES can catalyze the hydrolysis of compounds such as aliphatic carboxylates, fatty acid esters and thioesters, effectively inhibiting the binding of insecticides with insect detoxification and metabolic enzymes. AChE is an important enzyme that controls signal transmission in nerve cells and is also an important target for some insecticides. GST plays an important role in the detoxification of harmful compounds and the formation of insecticide resistance. CYP450 oxidizes xenobiotics, enhances the water solubility of xenobiotics, and promotes their excretion. MFO plays an important role in insecticide metabolism, resistance (resistance), etc. The induction of detoxification enzyme activity is a complex process, and different enzymes coordinate with each other to carry out detoxification metabolism. After α-terpineol fumigation, the activities of CES, AChE, GST, CYP450 and MFO in rice weevils and red flour beetles increased with the increase of treatment concentration. In order to maintain basic physiological activities, the two pests produced stress responses to external essential oil stimulation, activated the activities of five detoxification enzymes in the body, adapted to the exogenous stimulation of α-terpineol to achieve detoxification effects, and effectively maintained their normal growth and development. The toxic stress of exogenous α-terpineol substances increased the activity of detoxification enzymes, but the function of detoxification enzymes is a high-energy-consuming process, which hinders the growth and development of insects. The induction or inhibition of detoxification enzyme activity is not only affected by the concentration of toxic substances, but also the responses of different insect detoxification enzymes to different toxic substances are different.

[0025] 4. Serum amylase (AMS), trypsin and lipase can promote the synthesis and absorption of energy storage substances in insects, and are used to metabolize exogenous harmful compounds and adapt to the invasion of toxic substances. Under the fumigation of different time and different concentrations, α-pineneol in the present invention increases the activity of AMS, trypisin and lipase in rice weevils and red flour beetles, indicating that α-pineneol can maintain the normal physiological function of insects by increasing the activity of digestive enzymes in the bodies of insects. Insect digestive enzymes will inhibit the food intake and utilization of insects under the stress of pesticides, leading to delayed growth and development and diapause.

[0026] 5. Cinnamon bark oil crude oil and its isolates (light fraction of camphor bark oil residual oil, α-pineneol and 1,8-cineole) showed different biological activities against rice weevils and red flour beetles, among which α-pineneol had the strongest contact killing effect, 1,8-cineole had the most obvious fumigation effect, and α-pineneol had the second most obvious fumigation effect. Cinnamon bark oil crude oil and α-pineneol had strong repellent activity against red flour beetles at high concentrations. The repellent activity of the four essential oils on rice weevils was concentration-dependent, and 1,8-cineole and α-pineneol had time-dependence on rice weevils and red flour beetles, respectively. With the increase of α-pineneol treatment concentration, the activities of peroxidase (POD), five detoxification enzymes and three digestive enzymes in rice weevils and red flour beetles were activated, and the activities of catalase (CAT) and superoxide dismutase (SOD) were inhibited. As the treatment time of α-terpineol increased, the activities of glutathione S-transferase (GST), cytochrome P450 enzyme system (CYP450), and mixed function oxidase (MFO) in the two pests were activated, and other enzymes showed different trends of change. α-terpineol can induce or inhibit the activities of protective enzymes, detoxification enzymes, and digestive enzymes in pests, break the dynamic balance, disrupt their normal physiological metabolic activities, and produce toxic effects. α-terpineol can be used as a potential biological pesticide for rice weevils and red flour beetles, laying a theoretical foundation for molecular level research and green control of stored grain pests. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The results of the repellent activity of four essential oils on rice weevils after 2 hours of treatment;

[0028] Figure 2 The results of the repellent activity of 4 kinds of essential oils on rice weevils after 4 hours of treatment;

[0029] Figure 3 The results of the repellent activity of four essential oils on Tribolium castaneum after 2 hours of treatment;

[0030] Figure 4 The results of the repellent activity of four kinds of essential oils on Tribolium castaneum after 4 hours of treatment;

[0031] Figure 5 This is the result diagram of the effect of α-terpineol treatment at different time periods on the activities of different protective enzymes in rice weevils;

[0032] Figure 6 This is the result diagram of the effect of α-terpineol treatment at different time periods on the activities of different protective enzymes in Tribolium castaneum;

[0033] Figure 7 This is the result diagram of the effect of different treatment time of α-terpineol on the activity of different detoxification enzymes in rice weevils;

[0034] Figure 8 This is the result diagram of the effect of different treatment times of α-terpineol on the activities of different detoxification enzymes in Tribolium castaneum;

[0035] Fig. 9 This is the result diagram of the effect of different treatment time of α-terpineol on the activities of different digestive enzymes in rice weevils;

[0036] Fig.10 This is a graph showing the effects of different treatment times of α-pineneol on the activities of different digestive enzymes in Tribolium castaneum. DETAILED DESCRIPTION

[0037] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0038] Example 1

[0039] 1. Test insect source

[0040] The sources of rice weevils and red flour beetles were provided by the Agricultural Laboratory of the Department of Agriculture, Forestry and Food Engineering of Yibin University. The feed of rice weevils was whole wheat; the feed of red flour beetles was whole wheat flour and yeast mixed in a ratio of 10:1. Both test insects were placed in an incubator at (28±2)℃ and RH (75±5)%. After 7 days, the adults were screened out. After about one week of the emergence of a new generation of adults, the adults were screened out as test insects.

[0041] 2. Test essential oils

[0042] Cinnamomum camphora crude oil was obtained by steam distillation: Cinnamomum camphora leaves were crushed, mixed with water in a material-water ratio of 1:10 (g / mL), added into an extraction kettle, and steamed at 105-110°C for 2h. The upper oily liquid of the distillate was collected and the residual water was removed by an oil separator to obtain the Cinnamomum camphora crude oil.

[0043] The light fraction of camphor tree residual oil, 1,8-cineole (99.5%) and a-pineneol (99%) were all provided by Yibin Shiping Spice Co., Ltd.

[0044] Example 2 Contact Activity Determination

[0045] The test volume concentration range was determined by preliminary tests. Cinnamomum camphora crude oil, light fraction of camphora residual oil, 1,8-cineole and a-terpineol were diluted into 5 solutions of different volume concentrations using Span 80 and Tween 80 (1:2). The solutions were prepared into nanoscale using an ultra-high pressure nano homogenizer, and each gradient was repeated 3 times. A layer of filter paper was fixed on the bottom of a 9-cm diameter culture dish, and 0.3 mL of essential oil sample was dripped into it. After 30 seconds of evaporation, 10 test insects were placed in the center and crawled freely. Silk stockings and plastic wrap were put on the outside of the culture dish, holes were punched in the plastic wrap, and then tied with a rubber band, and cultured in an incubator. At the same time, an emulsifier was prepared with Span 80: Tween 80 = 1:2 as a negative control, and cypermethrin as a positive control. After 24 hours, the death of the test insects was observed and recorded, and the mortality rate and corrected mortality rate were calculated using the following formula. IBM SPSS V26.0 software was used for statistical analysis to calculate the median lethal dose LD50 / (μL / cm 2 ).

[0046] Mortality rate = number of dead insects / total number of insects treated × 100%

[0047] Corrected mortality rate = [(treatment group mortality rate minus control group mortality rate) / (1-control group mortality rate)] × 100%

[0048] The contact toxicity of crude camphor oil, residual camphor oil and monomer essential oil against rice weevil and red flour beetle is shown in Table 1.

[0049] Table 1 Contact activity of four essential oils against Siberian weevil and Tribolium castaneum

[0050]

[0051]

[0052] As shown in Table 1, the four essential oils all had good contact activity against the two stored-grain pests, and the LD 50 0.23, 0.24, 0.03 and 0.20 μL / cm 2 , LD of Tribolium castaneum 50 0.21, 0.27, 0.11 and 0.17 μL / cm respectively 2 α-Pinpineol had the strongest contact activity, followed by 1,8-cineole. There was no significant difference in the contact activity of Cinnamomum camphora crude oil and light fraction of Cinnamomum camphora residual oil against the two stored-grain pests.

[0053] Example 3 Fumigation Activity Determination

[0054] The test concentration range is determined by preliminary tests. The essential oil is diluted into 5 solutions with different volume gradients using the emulsifier in Example 2, and each gradient is repeated 3 times. Take 10 test insects and put them into a glass bottle with a volume of 50mL (diameter 3.8cm, height 9.5cm), hang a filter paper with a diameter of 10mm on the edge of the bottle cap, draw 10μL of essential oils of different concentrations and drop them on the filter paper, evaporate for 20s, tighten the bottle cap to form a closed space, and culture it in an incubator. The emulsifier is a negative control. After 24h, observe and record the death of each group of test insects, calculate the mortality rate and corrected mortality rate, and use IBMSPSS V26.0 statistical software to calculate the half-lethal concentration LC 50 / (μL / Lair).

[0055] The fumigation activities of crude camphor oil, light fraction of camphor oil residual oil and monomer essential oil against rice weevil and red flour beetle are shown in Table 2.

[0056] Table 2 Fumigation activity of four essential oils against rice weevils and red castaneum

[0057]

[0058]

[0059] As shown in Table 2, the four essential oils are fumigant toxic to the two stored-grain pests, and the fumigant activity of 1,8-cineole to rice weevils and red flour beetles is higher than that of the other three essential oils, corresponding to LC 50 and 12.97 and 13.23 μL / L air respectively, the fumigation activity of α-pineneol was 14.93 and 13.96 μL / L air respectively, the fumigation activity of crude camphor oil was 27.22 and 25.24 μL / Lair respectively, and the fumigation activity of the light component of camphor residual oil was 30.53 and 33.30 μL / L air respectively. It can be seen that 1,8-cineole has the best fumigation effect on rice weevils and red flour beetles, followed by α-pineneol, and camphor residual oil exhibits the weakest fumigation activity.

[0060] Example 4: Determination of repellent activity

[0061] The test concentration range was determined by preliminary experiments. The four essential oils were diluted into five different volume concentration gradients using the emulsifier in Example 2. Each gradient was repeated three times. A circular filter paper with a diameter of 9 cm was divided into two equal parts and fixed symmetrically on the bottom of a 9 cm culture dish. 0.3 mL of the emulsifier solution was dripped on one half of the filter paper, and then 0.3 mL of plant essential oils of different volume concentrations were evenly dripped on the other half of the filter paper. After evaporation for 30 seconds, 10 test insects were thrown into the center of the culture dish and allowed to disperse naturally. Stockings and plastic wrap were put on the outside of the culture dish, holes were punched in the plastic wrap, and then tied with a rubber band, and cultured in an incubator. Emulsifier and N, N-diethyl-m-toluamide (DEET) were used as negative and positive controls, respectively. Observation and statistics were performed at 2h and 4h after exposure to insects. The formula for calculating the repellency (PR) is as follows.

[0062] Repellency rate = (number of control insects + number of treated insects) / (number of control insects + number of treated insects) × 100%

[0063] The repellent activity of crude camphor oil, light fraction of camphor oil residue and essential oil against rice weevils Figure 1 and Figure 2 The repellent activity of Cinnamomum camphora crude oil, light fraction of Cinnamomum camphora residual oil and monomer essential oil against Tribolium castaneum is shown in Figure 3 and Figure 4 shown. Figure 1-Figure 4 Different letters on the same pattern indicate significant differences (P<0.05).

[0064] Depend on Figure 1 and Figure 2 It can be seen that the four camphor essential oils have a significant repellent effect on rice weevils. 2 When the concentration was 1.89 and 2.36 μL / cm 2 When treated for 4 h, when the essential oil concentration was 0.94 μL / cm 2 When the concentration was 1.42 and 1.89 μL / cm 2 The repellency rate of the light component of camphor oil residue was significantly higher than that of the crude oil, and there was no significant difference in the repellency rates of other essential oils. At 2 and 4 hours of treatment, the repellency rate of rice weevils increased with the increase of essential oil concentration, showing concentration effect and time effect.

[0065] Depend on Figure 3 and Figure 4It can be seen that at a concentration of 0.47 μL / cm 2 When the concentration was 0.94 and 1.42 μL / cm 2 When the concentration was 0.94 μL / cm 2 When the concentration of α-pineneol was 2.36 μL / cm2, the repellency rate of α-pineneol to red flour beetle was significantly higher than that of other essential oils. The repellency rate of 1,8-cineole to red flour beetle was the lowest, at 2.36 μL / cm2. 2 The repellency rate was negative. When the 2h effect at high concentration was extended to 4h, the repellency rate of the light components of camphor oil and 1,8-cineole to red flour beetle showed a downward trend. Except for the low concentration, the repellency rate of medium and high concentrations of α-pineneol to red flour beetle was greater than 80%, and was close to the positive control DEET.

[0066] Example 5 Enzyme activity determination

[0067] 1. Enzyme solution preparation

[0068] The best essential oils for rice weevils and red flour beetles were selected according to the contact test results of Example 2, the fumigation test results of Example 3, and the avoidance test results of Example 4. Then, according to the fumigation activity test results of Example 3, α-terpineol LC 50 Five fumigation times (6, 12, 18, 24, 30 h) and α-terpineol LC 25 , LC 50 , LC 75 The effects of three concentrations on the activities of protective enzymes, detoxifying enzymes and digestive enzymes in two kinds of pests for 24 hours were as shown in Example 3. The fumigation treatment without treatment was used as a control, and each treatment was repeated 3 times. 0.1 g of surviving adults after fumigation were selected, rinsed with pre-cooled PBS (0.01M, pH7.4, containing protease inhibitors), and then transferred to a glass homogenizer and fully homogenized in an ice bath. The sample tissue was centrifuged at 5000g for 5 minutes at 2-8°C, and the supernatant was collected as the enzyme solution to be tested, which was placed in a -80°C refrigerator for storage.

[0069] 2. Effect of α-terpineol on the activity of protective enzymes

[0070] 1) α-Terpineol LC 25 , LC 50 and LC 75 The effects of lethal concentrations on the activities of peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) in rice weevils and red castaneum are shown in Table 3.

[0071] Table 3 Effects of different concentrations of α-terpineol on the activities of protective enzymes of rice weevils and red castaneum

[0072]

[0073]

[0074] As shown in Table 3, with the increase of fumigation concentration, α-terpineol significantly induced the POD activity of rice weevils and red flour beetles, while the CAT and SOD activities showed a significant downward trend. 75 After 24 hours of fumigation treatment, the POD activities of rice weevil and red flour beetle were significantly higher than those of the control group, increasing by 37.0% and 39.0%, respectively; the CAT and SOD activities of the two pests in the LC75 essential oil group were the lowest, and the CAT activities of rice weevil and red flour beetle were reduced by 31.2% and 33.1% respectively compared with the control group, and the SOD activities of rice weevil and red flour beetle were reduced by 27.0% and 23.1% respectively compared with the control group.

[0075] 2) Using α-terpineol LC 50 The changes in the activities of protective enzymes (POD, CAT and SOD) in rice weevils and red castaneum at different time treatments were as follows: Figure 5 and Figure 6 shown. Figure 5 In the figure, A is the activity change of POD, B is the activity change of CAT, and C is the activity change of SOD. Figure 6 In the figure, A is the activity change of POD, B is the activity change of CAT, and C is the activity change of SOD. Figure 5 and Figure 6 In the code, different uppercase and lowercase letters represent LC 50 (CK) There were significant differences in treatment at different time points (P<0.05); ns means LC at the same time point 50 There was no significant difference between CK and CK, and “*” indicated significant difference (P<0.05).

[0076] Depend on Figure 5 and Figure 6It can be seen that after the rice weevil adults were fumigated with α-pineneol, the POD in their bodies first increased and then decreased with the extension of the treatment time, that is, the essential oil group was significantly higher than the control group at 24h treatment, and significantly lower than the control group at 30h treatment; the CAT activity of the rice weevil showed a "w"-shaped change with the extension of the treatment time, that is, it was significantly lower than the control group at 6 and 24h treatment, and the essential oil group was significantly higher than the control group at 18 and 30h treatment; the SOD activity first decreased, then increased, and then decreased relative to the control group, and the SOD activity of the essential oil group was the highest at 18h treatment; the POD and SOD in the adults of Tribolium castaneum were not significantly different from those of the control group under the action of α-pineneol for 6-24h treatment, but the POD activity was significantly higher than the control group at 30h treatment, and the SOD activity was significantly lower than the control group. The CAT activity was significantly lower than the control group only at 18h treatment.

[0077] 3. Effect of α-terpineol on the activity of detoxification enzymes

[0078] 1) α-Terpineol LC 25 , LC 50 and LC 75 The effects of lethal concentrations on the activities of carboxylesterase (CES), acetylcholinesterase (AChE), glutathione S-transferase (GST), cytochrome P450 enzyme system (CYP450) and mixed function oxidase (MFO) detoxification enzymes in rice weevils and red castanea are shown in Table 4.

[0079] Table 4 Effects of different concentrations of α-terpineol on the detoxification enzyme activities of rice weevils and red castaneum

[0080]

[0081] As shown in Table 4, with the increase of essential oil fumigation concentration, the activities of five detoxification enzymes in the two stored-grain pests were activated. 75 When the concentration is high, the enzyme activity in the pest is the highest.

[0082] 2) α-Terpineol LC 50 The changes of detoxification enzyme activities (CES, AChE, GST, CYP450 and MFO) in rice weevils and red castaneum beetles treated at different time periods were shown in Figure 2 Figure 7 and Figure 8 shown. Figure 7 In the experiment, AEs were the activity changes of CES, AChE, GST, CYP450 and MFO. Figure 8 In the experiment, AEs were the activity changes of CES, AChE, GST, CYP450 and MFO.

[0083] Depend on Figure 7 and Figure 8It can be seen that with the extension of α-pineneol treatment time, the GST, CYP450 and MFO activities of rice weevils and red flour beetles were activated, among which the three detoxification enzymes were significantly higher than those of the control group at 24h treatment time. The AChE activity of rice weevils first increased and then decreased compared with the control group, that is, it was significantly higher than the control group during the treatment period of 6-14h, and significantly lower than the control group at 30h; the CES activity was significantly lower than the control group only at 18h treatment, and then there was no significant difference with the control group as the treatment time increased. The CES activity of red flour beetles was activated during the 12-30h essential oil treatment period, and the AChE activity was significantly higher than the control group only at 24h, and then there was no significant difference with the control group as the treatment time increased.

[0084] 4. Effect of α-terpineol on digestive enzyme activity

[0085] 1) α-Terpineol LC 25 , LC 50 and LC 75 The effects of lethal concentration on the activities of serum amylase (AMS), lipase (Lipase) and protease (Trypsi) in rice weevils and red flour beetles are shown in Table 5.

[0086] Table 5 Effects of different concentrations of α-terpineol on the digestive enzyme activities of rice weevils and red castaneum

[0087]

[0088]

[0089] As shown in Table 5, with the increase of α-terpineol treatment concentration, the activities of AMS, lipase and trypsin in rice weevils and red castaneum showed an upward trend, especially the α-terpineol LC 75 The activities of the three digestive enzymes in the lethal concentration treatment were significantly higher than those in the control group.

[0090] 2) Effects of α-terpineol treatment at different time periods on the activities of three digestive enzymes in rice weevils and red flour beetles Fig. 9 and Fig.10 shown.

[0091] Depend on Fig. 9 and Fig.10 It can be seen that with the extension of α-terpineol treatment time, the AMS and lipase activities of rice weevils showed an "N"-shaped change trend, both significantly lower than the control group at 18h, and trypsin activity in the essential oil group was inhibited at 30h. However, the AMS activity of red castaneum was significantly higher than that of the control group only at 24h, trypsin activity was first activated and then inhibited, and lipase activity was no different from the control group.

[0092] In summary, the crude oil and its isolates (light fraction of the residual oil of camphor, α-terpineol and 1,8-cineole) showed different biological activities against rice weevils and red flour beetles, among which α-terpineol had the strongest contact killing effect, 1,8-cineole had the most obvious fumigation effect, and α-terpineol had the second strongest fumigation effect. Cinnamon oil and α-terpineol had strong repellent activity against red flour beetles at high concentrations. The repellent activity of the four essential oils on rice weevils was concentration-dependent, and 1,8-cineole and α-terpineol had time-dependence on rice weevils and red flour beetles, respectively. The insecticidal mechanism showed that the enzyme activity in the pests was not only affected by the concentration and time of the essential oil, but also that the enzyme activity in different pests responded differently to the same essential oil. With the increase of the treatment concentration of α-terpineol, the activities of POD, five detoxification enzymes and three digestive enzymes in rice weevils and red flour beetles were activated, and the activities of CAT and SOD were inhibited. As the treatment time of α-terpineol increased, the activities of GST, CYP450, and MFO in the two pests were activated, and other enzymes showed different trends of change. α-terpineol can induce or inhibit the activities of protective enzymes, detoxification enzymes, and digestive enzymes in pests, break the dynamic balance, disrupt their normal physiological metabolic activities, and produce toxic effects. α-terpineol can be used as a potential biological pesticide for rice weevils and red flour beetles, laying a theoretical foundation for molecular-level research and green control of stored-grain pests.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Application of camphor essential oil in any of the following (1)-(4): (1) Control of stored grain pests; (2) Preparation of products for controlling stored-grain pests; (3) disrupting the normal physiological and metabolic activities of stored-grain pests; (4) Preparing products that disrupt the normal physiological and metabolic activities of stored-grain pests.

2. The use according to claim 1, characterized in that The camphor essential oil is at least one of camphor crude oil, camphor residual oil light components, α-terpineol and 1,8-cineole.

3. The use according to claim 2, characterized in that The camphor oil crude oil is prepared from camphor leaves through a steam distillation method.

4. The use according to claim 2, characterized in that The light component of the camphor oil residue is prepared by the following method: S1. Separate and collect cineole, eucalyptus oil, terpineol, α-terpineol, camphor, β-caryophyllene, white camphor oil, γ-terpineol, terpinene-4-ol, terpinene, α-pinene, δ-terpineol, β-phellandrene, myrcene, butyl-terpineol and propyl-terpinene from the crude camphor oil by distillation and freeze-crystallization separation and purification technology to obtain camphor oil residual oil; S2. Separating the camphor oil residue obtained in step S1 by vacuum distillation technology to obtain a light component of the camphor oil residue.

5. The use according to claim 4, characterized in that In step S2, the density of the light component of the camphor oil residue is 0.8-0.9 g / cm 3 .

6. The use according to claim 1, characterized in that The stored-grain pests are rice weevils and / or red flour beetles.

7. The use according to claim 1, characterized in that The contact concentration of the camphor essential oil is 0.01-0.42 μL / cm 2 The fumigation concentration of the camphor essential oil is 6-42 μL / L air.

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