An attractant for millet leafminer and its application method

Abstract

This invention belongs to the field of agricultural planting technology, specifically relating to an attractant for millet leafhoppers and its application method. The attractant, by weight, comprises the following components: 5-10 parts millet leaf extract, 30-40 parts n-hexane, 1-2 parts dispersant, and 1-2 parts starch dextrin. The millet leaf extract includes 2-ethylhexanol, nonanal, 1-octen-3-ol, myrcene, tridecane, tetradecane, and eucalyptol. This invention, by using millet leaf extract as the main component and other alcohols, aldehydes, and alkenes as auxiliary additives, allows the substances in the leaves that attract millet leafhoppers to volatilize and diffuse, thus making the attractant's attraction to millet leafhoppers much greater than that of millet seedlings, thereby preventing millet leafhoppers from harming millet seedlings.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting technology, specifically relating to an attractant for millet leafminer and its application method. Background Technology

[0002] The millet leaf beetle (Oulema tristis Herbst.), also known as the millet leaf beetle, belongs to the family Oulematidae in the order Coleoptera. It is distributed in Heilongjiang, Jilin, Liaoning, Inner Mongolia, Ningxia, Gansu, Shaanxi, Shanxi, Hebei, Henan, and Beijing in my country. This insect primarily damages millet, but can also infest sorghum, foxtail millet, and various grasses. The larvae are the main damage larvae, which hide inside the heart leaves and feed on the leaf tissue, creating broad, white, streaky feeding marks. In severe cases, this can cause the heart to wither, the seedlings to rot, or the entire plant to die. Adults can also cause damage, feeding along the veins and leaving only the epidermis, forming long white streaks. In severe cases, the leaves can break into filamentous pieces.

[0003] In recent years, the implementation of cropping practices such as straw return to the field and no-till planting has provided convenient conditions for the overwintering of millet leafminer. In severely affected areas, the number of leafminers can reach 300 to 600 per 100 plants, with more than 20 leafminers per plant, and the damage rate is over 90%. It has become the main pest of millet, posing a serious threat to both the yield and quality of millet.

[0004] Because the millet leafminer larvae hide inside the heart leaves of millet, their symptoms are not obvious and easily go unnoticed. By the time the millet reaches the jointing stage and white, scorched leaves appear in large numbers, the optimal control period has passed. Production mainly focuses on controlling overwintering adults, but adults have a long survival time and can continuously migrate into millet fields, making chemical pesticide application difficult. Furthermore, excessive use of chemical pesticides can have a series of negative impacts, including environmental safety, food safety, and the development of pesticide resistance in pests. Therefore, developing green control technologies conducive to sustainable development is essential. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an attractant for millet leafhoppers and its application method. By using millet leaf extract as the main component and other alcohols, aldehydes, and olefins as auxiliary additives, the substances in the leaves that attract millet leafhoppers can be volatilized and diffused. This makes the attractant's attraction to millet leafhoppers much greater than that of millet seedlings, thereby preventing millet leafhoppers from harming millet seedlings.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] An attractant for millet leaf beetle, comprising, by weight, the following components: 5-10 parts millet leaf extract, 30-40 parts n-hexane, 1-2 parts dispersant, and 1-2 parts starch dextrin.

[0008] The millet leaf extract includes 2-ethylhexanol, nonanal, 1-octen-3-ol, myrcene, tridecane, tetradecane, and eucalyptol.

[0009] Furthermore, an attractant for millet leafhoppers, by weight, comprises the following components: 5-10 parts millet leaf extract, 0.5-1.5 parts trans-2-hexenal, 1-1.5 parts citral, 0.5-1 part ocimene, 30-40 parts n-hexane, 1-2 parts dispersant, and 1-2 parts starch dextrin.

[0010] The method for obtaining millet leaf extract includes the following steps:

[0011] A1. Place the millet seedling leaves in the flange reactor and seal it with sealing film. Connect activated carbon to the bottom of the reactor and air inlet pipe and adsorbent pipe to the top. After connecting the atmospheric sampler, use a flow meter to check the airtightness of the device.

[0012] A2. After pre-evacuating the flange reactor for 30-40 minutes, connect the adsorption column and collect the gas for 18-24 hours.

[0013] A3. After collection, the volatile substances collected in the adsorption column are eluted with n-hexane, which is the millet leaf extract.

[0014] The air flow rate of the atmospheric sampler mentioned in step A1 is 500 mL / min.

[0015] The preparation method of the attractant includes the following steps:

[0016] B1. First, add the millet leaf extract to 20-25 parts of n-hexane and stir until homogeneous to obtain the inducing base solution;

[0017] B2. Add trans-2-hexenal, citral and ocimene to the remaining n-hexane, then add dispersant and stir until homogeneous to obtain the auxiliary solution;

[0018] B3. Mix the attractant base liquid and auxiliary liquid, add dispersant and stir evenly, then add starch dextrin in batches and stir evenly to obtain the attractant.

[0019] The specific steps for using attractants include:

[0020] S1. Add the attractant to the sustained-release carrier and then seal it to make the lure core;

[0021] S2. Place the lure on the trap and hang it in the valley.

[0022] Furthermore, the sustained-release carrier is a polyethylene bottle.

[0023] Furthermore, the traps are arranged in a rectangular array within the valley, with a deployment density of 80-120m. 2 Set up a set of traps.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention studies the components of millet leaves, which the millet leaf beetle feeds on, and screens out volatile components with attraction activity against the millet leaf beetle, thus developing an attractant. The attractant components are derived from plant leaves, are non-toxic and leave no residue, and will not cause environmental pollution. Simultaneously, the attractant can attract and kill adult beetles, reducing their offspring population size, and has significant control value, making it an ideal green control technology.

[0026] 2. In this invention, by using millet leaf extract as the main component and other alcohols, aldehydes, and alkenes as auxiliary components, the substances in the leaves that attract millet leaf beetles can be volatilized and diffused. This makes the attraction of the attractant to millet leaf beetles much greater than that of millet to millet leaf beetles. By using the attractant to lure and capture millet leaf beetles, the millet leaf beetles are prevented from feeding on and harming the millet.

[0027] 3. In this invention, hexane is used as a solvent and a dispersant is added, which can better mix the active substances in the components. At the same time, hexane itself has good volatility, which further improves the attraction effect of the attractant on the millet leaf beetle. Attached Figure Description

[0028] Figure 1 The response of male and female adult millet leaf beetles to different doses of seven volatile substances using EAG.

[0029] Figure 2 The behavioral response of female adult millet leaf beetles to seven volatile standard samples of different mass concentrations;

[0030] Figure 3 The behavioral response of male adult millet leafminer to seven volatile standard samples of different mass concentrations was studied. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. I. Specific Implementation Methods

[0033] 1. Extraction of millet leaf extract

[0034] Includes the following steps:

[0035] A1. Place the millet seedling leaves in the flange reactor and seal it with sealing film. Connect activated carbon to the bottom of the reactor and air inlet pipe and adsorbent pipe to the top. After connecting the atmospheric sampler, use a flow meter to check the airtightness of the device.

[0036] The air flow rate of the atmospheric sampler is 500 mL / min;

[0037] A2. After pre-evacuating the flange reactor for 30 minutes, connect the adsorption column and collect data from 8:00 AM to 8:00 AM the next day, for a total of 24 hours.

[0038] A3. After collection, the volatile substances collected in the adsorption column were eluted with 1 mL of chromatographically pure n-hexane, which is the millet leaf extract.

[0039] 2. Preparation of attractants

[0040] Example 1

[0041] B1. First, add 8 parts of leaf extract to 25 parts of n-hexane and stir until homogeneous to obtain the inducing base solution;

[0042] B2. Add 2 parts of dispersant to the attractant base liquid and stir evenly. Then add 1.5 parts of starch dextrin in batches and stir evenly to obtain the attractant.

[0043] Example 2

[0044] B1. First, add 5 parts of leaf extract to 20 parts of n-hexane and stir until homogeneous to obtain the inducing base solution;

[0045] B2. Add 1 part dispersant to the attractant base liquid and stir evenly. Then add 1 part starch dextrin in batches and stir evenly to obtain the attractant.

[0046] Example 3

[0047] B1. First, add 10 parts of leaf extract to 30 parts of n-hexane and stir until homogeneous to obtain the inducing base solution;

[0048] B2. Add 1.5 parts of trans-2-hexenal, 1.5 parts of citral and 1 part of ocimene to 10 parts of n-hexane and stir until homogeneous to obtain the auxiliary solution.

[0049] B3. Mix the attractant base liquid and auxiliary liquid, add 2 parts of dispersant and stir evenly. Then add 2 parts of starch dextrin in batches and stir evenly to obtain the attractant.

[0050] Example 4

[0051] B1. First, add 6 parts of leaf extract to 15 parts of n-hexane and stir until homogeneous to obtain the inducing base solution;

[0052] B2. Add 1.2 parts of trans-2-hexenal, 1.5 parts of citral and 0.6 parts of ocimene to 15 parts of n-hexane and stir until homogeneous to obtain the auxiliary solution;

[0053] B3. Mix the attractant base liquid and auxiliary liquid, add 1.5 parts of dispersant and stir evenly, then add 1 part of starch dextrin in batches and stir evenly to obtain the attractant.

[0054] Example 5

[0055] B1. First, add 8 parts of leaf extract to 25 parts of n-hexane and stir until homogeneous to obtain the inducing base solution;

[0056] B2. Add 1 part of trans-2-hexenal, 1.2 parts of citral and 0.8 parts of ocimene to 10 parts of n-hexane and stir until homogeneous to obtain the auxiliary solution;

[0057] B3. Mix the attractant base liquid and auxiliary liquid, add 2 parts of dispersant and stir evenly, then add 1.5 parts of starch dextrin in batches and stir evenly to obtain the attractant.

[0058] Comparative Example 1

[0059] The only difference between Comparative Example 1 and Example 3 is that Comparative Example 1 does not contain millet leaf extract. The specific steps are as follows:

[0060] B1. Add 1.5 parts of trans-2-hexenal, 1.5 parts of citral and 1 part of ocimene to 20 parts of n-hexane and stir until homogeneous to obtain the inducing base solution;

[0061] B3. Add 1 part dispersant to the attractant base liquid and stir evenly. Then add 1 part starch dextrin in batches and stir evenly to obtain the attractant.

[0062] II. Performance Testing

[0063] 1. Identification of volatile components in millet:

[0064] The collection of volatiles employed a dynamic headspace sampling method. During collection, the plant roots were first wrapped with aluminum foil. The lower half of the flange reactor was tilted slightly, and the plant was gently placed along the cover. The upper half of the reactor was then replaced and sealed with sealing film. Activated carbon was connected to the bottom of the reactor, and the air inlet and adsorbent tubes were connected to the top. During evacuation, the air sampler's flow rate was 500 mL / min, and the airtightness of the apparatus was checked using a flow meter. All silicone tubing used to connect the entire apparatus was Teflon tubing with no volatile gases. To avoid any off-odors, the collection system was pre-evacuated for 30 minutes before connecting the adsorption column. The collection time for all plants was set to 24 hours. Immediately after collection, the adsorption column was removed, and the collected plant volatiles were eluted with 1 mL of chromatographically pure hexane into a sample vial and stored at -20°C for later use. Simultaneously, air (an empty flange reactor without plants) was collected for 24 hours as a blank control.

[0065] The volatile matter samples of millet collected by dynamic headspace analysis were analyzed by GC-MS, and after searching the NIST14 spectral library and combining standard quality spectra and retention times, 18 compounds were identified. The percentage content of each component was calculated using the peak area normalization method. The analytical results are shown in Table 1. The main types of volatile matter in millet include aldehydes, alkenes, alcohols, and alkanes, with alcohols and alkenes having the highest relative contents, accounting for more than 85%, which is significantly higher than other types of compounds.

[0066] Table 1

[0067] 1 decane 3.494 0.50 2 α-pinene 3.785 2.13 3 Undecane 4.769 0.06 4 1,3,5-Octatriene 4.955 14.72 4 β-Phragmitesin 5.345 0.47 6 β-Myrcene 6.156 0.94 7 Limonene 6.902 2.53 8 dodecane 7.015 0.87 9 Eucalyptol 7.179 3.85 10 styrene 8.142 1.19 11 Tridecane 9.356 5.89 12 Nononal 11.497 0.83 13 Tetradecane 11.801 6.17 14 1-Octen-3-ol 12.950 10.15 15 2-Ethylhexanol 13.910 17.33 16 β-elemene 16.426 24.51 17 β-Cubanene 19.362 6.16 18 β-juniperene 20.240 1.69

[0068] 2. Antennae potential experiment:

[0069] Each volatile standard compound was serially diluted with n-hexane to prepare solutions with five series concentrations (100, 10, 1, 0.1, and 0.01 μg / mL), with n-hexane as a blank control. The entire antennae of active male and female adult millet leaf beetles were cut off from the base, the tips were removed, and the two ends of the antennae were connected to electrodes coated with conductive adhesive using insect needles. After the baseline stabilized, electrophysiological activity tests were performed.

[0070] Take 10 μL of the sample solution to be tested and spread it evenly on a filter paper strip (5.0 cm × 0.5 cm). After the solvent evaporates, place it in a Pasteur tube and then connect the Pasteur tube to the stimulation gas flow. Adjust the continuous gas flow rate to 500 mL / min and the stimulation gas flow rate to 40 mL / min. Each stimulation time is 0.1 s, and the interval between two stimulations is 30 s to restore the sensitivity of the antennae. Five antennae of each sample, both male and female adults, are tested. Using n-hexane as a control, one test is performed before and after the initial test. The ambient temperature during the experiment is 25℃ ± 1℃, and the humidity is 60%–70%. The test results are shown in […]. Figure 1 The volatile compounds used in Figures A, B, C, D, E, F, G, are, in order: A: 2-ethylhexanol; B: nonanal; C: 1-octen-3-ol; D: myrcene; E: tridecane; F: tetradecane; G: eucalyptol.

[0071] The results showed that adult male and female *Cephalotaxus fortunei* exhibited no significant EAG response to three volatile compounds: tridecane, tetradecane, and eucalyptol. Furthermore, the EAG response values ​​remained essentially unchanged with increasing volatile compound concentration. Adult male and female *Cephalotaxus fortunei* produced strong EAG responses to four volatile compounds: 2-ethylhexanol, nonanal, 1-octen-3-ol, and myrcene. The EAG response increased with increasing volatile compound concentration; at lower concentrations, almost no EAG response was observed, while a strong EAG response was observed at the maximum test concentration of 100 μL / mL. Among these, the female adult *Cephalotaxus fortunei* showed a stronger response to nonanal and 1-octen-3-ol compared to 2-ethylhexanol and myrcene.

[0072] 3. The tactile response of the millet leaf beetle to seven volatile substances:

[0073] The behavioral responses of male and female adult *Carex chinensis* to volatile compounds from seven plants were determined using a Y-shaped olfactometer. The Y-shaped olfactometer was made of colorless, transparent glass with an inner diameter of 3 cm. Its base was a straight tube 25 cm long, and each of its two arms was 20 cm long, with an angle of 75° between the arms. Before testing, the Y-shaped tube was connected to the odor source using silicone tubing of equal length. A QC-1B atmospheric sampler was used as the airflow propulsion system, and the odor source was connected to a vacuum pump. Before entering the odor source, the airflow passed through an activated carbon filter and a distilled water washing bottle to purify the airflow and increase its humidity. The gas flow rate was controlled at 200 mL / min. A 20 μL volatile compound solution was used as the odor source. Filter paper strips containing the volatile compound were placed on both arms of the Y-shaped tube. The atmospheric sampler was turned on, and the airflow was allowed to fill the entire apparatus with odor for 10 minutes. Then, a single adult *Carex chinensis* was introduced into the olfactometer using a centrifuge tube, and the insect's behavioral response was observed over 10 minutes.

[0074] The evaluation criteria are as follows: If the insect flies to more than halfway along one arm and stays there for more than 30 seconds, or flies directly to the end of that arm, it is considered to have responded to the volatile substance. If, within 10 minutes, the insect only hovers within the straight tube or moves rapidly between the two arms, it is considered to have no obvious preference for the volatile substance and is recorded as having no response. For each odor source combination test, 50 female and 50 male adult *Cephalotaxus fortunei* were used. Each adult was tested only once. Every 5 insects tested, the two arms of the "Y"-shaped olfactory apparatus were swapped. After testing 10 insects, the "Y"-shaped olfactory apparatus was cleaned with acetone and dried.

[0075] Figure 2 The behavioral responses of female adult millet leaf beetles to seven volatile standard samples at different mass concentrations were investigated. The results showed that 2-ethylhexanol, nonanal, 1-octen-3-ol, and myrcene at concentrations of 0.01, 0.1, 1, 10, and 100 μg / mL all exhibited highly significant attractant effects (P<0.01). Eucalyptol showed highly significant attractant effects at concentrations of 10 and 100 μg / mL (P<0.01). Tetradecane showed significant attractant effects at concentrations of 10 and 100 μg / mL (P<0.05). Tridecane, however, only showed significant attractant effects at a concentration of 100 μg / mL (P<0.05).

[0076] Figure 3The behavioral responses of male adult millet leaf beetles to seven volatile organic compound standards at different concentrations were investigated. The results showed that myrcene had a highly significant attractant effect on male adults at five concentrations (0.01, 0.1, 1, 10, and 100 μg / mL) (P < 0.01). 1-Octen-3-ol had a highly significant attractant effect on male adults at four concentrations (0.1, 1, 10, and 100 μg / mL) (P < 0.01). 2-Ethylhexanol and nonanal had highly significant attractant effects on male adults at three concentrations (1, 10, and 100 μg / mL) (P < 0.01). Eucalyptol had a highly significant attractant effect at concentrations of 10 and 100 μg / mL (P < 0.01). Tridecane and tetradecane only had a significant attractant effect on the insect at a concentration of 100 μg / mL (P < 0.05).

[0077] 4. Testing of Examples and Comparative Examples

[0078] The attractants prepared in Examples 1-5 and Comparative Example 1 were made into lures and placed into traps. The field was divided into regions 1-7. The traps prepared in Example 1 were placed in region 1, the traps prepared in Example 2 were placed in region 2, and so on. Region 7 served as a blank control group and no traps were placed there.

[0079] Field management was carried out in areas 1-7 using the same irrigation, fertilization and other management parameters. No pesticides were sprayed or insects were manually caught during the period. The growth of millet and the number of millet leafminer trapped by the traps were counted every 7 days. Table 2 shows the growth of millet and Table 3 shows the number of millet leafminer trapped.

[0080] Table 2

[0081]

[0082] Table 3

[0083]

[0084] As can be seen from Tables 2 and 3, the attractants prepared in Examples 3-5 have a greater attraction effect on millet leaf beetles. This is because the combination of trans-2-hexenal, citral, and ocimene increases the volatility of volatiles in millet leaves, thereby enhancing the attraction effect on millet leaf beetles.

Claims

1. An attractant for millet leafminer, characterized in that, By weight, it includes the following components: 5-10 parts millet leaf extract, 0.5-1.5 parts trans-2-hexenal, 1-1.5 parts citral, 0.5-1 part ocimene, 30-40 parts n-hexane, 1-2 parts dispersant and 1-2 parts starch dextrin. The millet leaf extract includes 2-ethylhexanol, nonanal, 1-octen-3-ol, myrcene, tridecane, tetradecane, and eucalyptol; The method for obtaining the millet leaf extract includes the following steps: A1. Place the millet seedling leaves in the flange reactor and seal it with sealing film. Connect activated carbon to the bottom of the reactor and connect the air inlet pipe and adsorbent pipe of the air sampler to the top. After connecting the air sampler, use a flow meter to check the airtightness of the device. A2. After pre-evacuating the flange reactor for 30-40 minutes, connect the adsorption column and collect the gas for 18-24 hours. A3. After collection, the volatile substances collected in the adsorption column are eluted with n-hexane, which is the millet leaf extract.

2. The attractant for millet leafminer in millet according to claim 1, characterized in that, The air flow rate of the atmospheric sampler mentioned in step A1 is 500 mL / min.

3. A method for preparing an attractant for millet leafminer in millet according to claim 1, characterized in that, The method for preparing the attractant includes the following steps: B1. First, add the millet leaf extract to 20-25 parts of n-hexane and stir until homogeneous to obtain the inducing base solution; B2. Add trans-2-hexenal, citral and ocimene to the remaining n-hexane and stir until homogeneous to obtain the auxiliary solution; B3. Mix the attractant base liquid and auxiliary liquid, add dispersant and stir evenly, then add starch dextrin in batches and stir evenly to obtain the attractant.

4. A method for using an attractant for millet leafminer in millet as described in claim 1, characterized in that, The method of using the attractant specifically includes the following steps: S1. Add the attractant to the sustained-release carrier and then seal it to make the lure core; S2. Place the lure on the trap and hang it in the valley.

5. The method of using an attractant for millet leafminer in millet according to claim 4, characterized in that, The slow-release carrier is a polyethylene bottle.

6. The method of using an attractant for millet leafminer in millet according to claim 4, characterized in that, The traps are arranged in a rectangular array within the valley, with a density of 80-120m. 2 Set up a set of traps.

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