Prediction and forecast method for spodoptera frugiperda based on juvenile hormone titer
By detecting the teenage hormone titer of female fallopian worms and classifying the ovarian development progress, the peak period of the next generation of adults of fallopian worms in the grassland was calculated, and the problem of difficulty in accurately predicting the peak period of the fallopian adults in the existing technology was solved, and more accurate predictions and more effective prevention and control measures were achieved.
Patent Information
- Application Number
- CN202510249691.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-06-17
AI Technical Summary
The prior art is difficult to accurately predict the peak period of fall armyworm adults, resulting in poor control effects.
By detecting the teenage hormone titer in the bodies of female fall armyworms, the progress of ovarian development is graded, and the peak period of the next generation of adults is estimated.
This method is simple, fast and accurate, and can predict the peak period of the next generation of adults from contemporary adults, providing sufficient preparation time for timely prevention and control.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of pest prediction and forecasting, and specifically relates to a fall armyworm prediction and forecasting method based on juvenile hormone titer. Background Art
[0002] Fall armyworm is an omnivorous insect. Its larvae can feed on 353 species of plants from 76 families, including Gramineae, Asteraceae, and Leguminosae. It especially causes serious damage to food and cash crops such as corn, rice, sorghum, soybeans, cotton, peanuts, and sugarcane. As fall armyworm larvae are highly concealed and difficult to control, timely control during the peak period of adult emergence is the key to controlling its damage, and accurately predicting the peak period of adult emergence is the prerequisite for ensuring effective control.
[0003] In addition to its omnivorous nature, the fall armyworm also has the characteristics of fast development and strong reproductive capacity. The prevention and control situation is very serious. In September 2020, the Ministry of Agriculture and Rural Affairs listed the fall armyworm as the first category of crop pests. The adult fall armyworm has a strong ability to migrate and spread. At present, there are few prediction methods for fall armyworm, and it is difficult to accurately predict its damage. There is an urgent need for prediction methods to meet the actual needs of precise prevention and control of fall armyworm. Summary of the invention
[0004] The purpose of the present invention is to provide a method for predicting and forecasting fall armyworm based on the titer range of female juvenile hormone. The method can estimate the peak period of occurrence of the next generation of adults based on the current adults. The method is simple, fast and accurate, and greatly increases the time span of the prediction, thereby improving the efficiency of the prediction and forecast.
[0005] To achieve the above object, the present invention adopts the following technical solutions.
[0006] The method for predicting fall armyworm based on the titer range of female insect juvenile hormone of the present invention comprises the following steps:
[0007] A. Detection of three juvenile hormones in female Spodoptera frugiperda by liquid chromatography-mass spectrometry: Take 0.1-0.5 g of Spodoptera frugiperda, add grinding balls, add 2 mL of mixed solution (0.9% sodium chloride solution: acetonitrile = 1:1), 3 mL of n-hexane, shake for 3 min, centrifuge at 4000 r / min for 5 min, transfer the supernatant, add 3 mL of n-hexane, repeat the extraction twice, combine the extracted n-hexane layers into a collection bottle,
[0008] The mixture was dried by nitrogen blowing, fixed to volume with 0.2 mL of acetonitrile-methanol solution, filtered through an organic double-layer filter membrane, and analyzed using a high performance liquid phase tandem mass spectrometer;
[0009] B. Ovarian development progress classification: According to the juvenile hormone titer range, ovarian development is divided into 5 levels, namely, milky white transparent stage (level I), yolk deposition stage (level II), mature and ready to lay stage (level III), peak egg-laying stage (level IV) and late egg-laying stage (level V); among them, in the stage I ovary stage, the juvenile hormone titer ranges of female Spodoptera frugiperda are JHⅠ (0.55-0.78 ng / g), JHⅡ (0.81-1.00 ng / g), JHⅢ (0.54-0.64 ng / g); in the stage II ovary stage, the juvenile hormone titer ranges of female Spodoptera frugiperda are During the stage III ovarian period, the juvenile hormone titers of female Spodoptera frugiperda were JHⅠ(0.87~1.76ng / g), JHⅡ(1.21~1.62ng / g), and JHⅢ(1.03~1.49ng / g), respectively. During the stage IV ovarian period, the juvenile hormone titers of female Spodoptera frugiperda were JHⅠ(2.13~2.93ng / g), JHⅡ(2.07~2.21ng / g), and JHⅢ(0.95~1.01ng / g), respectively.
[0010] (1.68~1.98ng / g), JHⅢ(0.47~0.71ng / g); in the V-stage ovarian period, the juvenile hormone titer ranges of female Spodoptera frugiperda were JHⅠ(1.44~1.50ng / g), JHⅡ(1.40~1.58ng / g), and JHⅢ(1.50~1.63ng / g);
[0011] C. Main level of ovarian development: Collect the adults of fall armyworm in corn fields, test the titers of JHⅠ, JHⅡ, and JHⅢ, determine the ovarian development level of each individual by the titer of juvenile hormone, count the percentage of female insects at each ovarian development level to the total number of female insects, and add up the percentages of ovaries at each level in the order of V to I ovaries. When the accumulated value reaches 50%, stop adding up, and determine the lowest ovarian development level among the accumulated ovarian development levels as the main level of ovarian development, which is used to estimate the peak period of the next generation of adults.
[0012] Peak period of adult emergence of the next generation: The peak period of egg-laying of the current generation of adults can be estimated based on the ovarian development level of the adults. The formula is: Peak period of egg-laying = sample collection date ± |Level IV ovarian development period - ovarian development main level development period |. When the main level of ovarian development is not higher than Level IV ovaries, addition is used; when the main level of ovarian development is Level V ovaries, subtraction is used.
[0013] The formula for calculating the peak period of adult emergence of the next generation is: the peak period of adult emergence of the next generation = the peak period of egg-laying + the sum of the developmental period from the egg stage to the pupal stage.
[0014] Preferably, the liquid chromatography separation conditions are as follows: C18 chromatographic column (100 mm × 2.1 mm, 1.8 μm), column temperature 30 °C, injection volume 15 μL; mobile phase: A is 0.1% formic acid in water, B is 0.1% formic acid in acetonitrile;
[0015] Preferably, the mass spectrometry conditions are as follows: the mass spectrometer used is a triple quadrupole tandem mass spectrometer, electrospray ionization source (ESI), multiple reaction monitoring (MRM), positive ion mode, spray voltage 5500 eV, temperature 550 °C, curtain gas pressure: 0.24 MPa; collision gas pressure 0.02 MPa; collision cell entrance voltage 10 V; collision gas exit voltage 15 V; ion source Gas1: 50 psi; Gas2: 50 psi;
[0016] Preferably, by raising Spodoptera frugiperda in the laboratory, the development durations of ovaries at all levels and various insect stages are counted. Three replicates are set up, with 200 insects in each group. Observe and record the development durations of ovaries at all levels, as well as the development durations of eggs, larvae, prepupae, and pupae.
[0017] Preferably, during the calculation of the emergence peak period of the next generation of adults, the detailed values of the development durations of ovaries at all levels are as follows: the development duration of grade I ovaries is 1.52 days, the development duration of grade II ovaries is 2.75 days, the development duration of grade III ovaries is 3.25 days, the development duration of grade IV ovaries is 4.67 days, and the development duration of grade V ovaries is 5.53 days.
[0018] Preferably, the development durations of eggs, larvae, prepupae, and pupae are as follows: the development duration of eggs is 6.54 days, the development duration of larvae is 11.82 days, the development duration of prepupae is 1.85 days, and the development duration of pupae is 5.46 days.
[0019] Preferably, the Spodoptera frugiperda adults in the cornfield are collected by the five-point sampling method.
[0020] Preferably, the ovaries of female insects are dissected under a stereomicroscope.
[0021] The beneficial effects obtained by the present invention are as follows:
[0022] The present invention can predict the occurrence peak period of the next generation of adults from the current generation of adults. Compared with the direct ovarian dissection prediction method, this method is simple, fast, and accurate, and can provide sufficient preparation time for the timely control of the next generation of adults.
[0023] The present invention fills the technical gap of not using adults for prediction and provides an effective means for predicting and forecasting Spodoptera frugiperda adults, enriching the technical system for predicting and forecasting Spodoptera frugiperda. Description of the Drawings
[0024] Figure 1Standard sample spectra of juvenile hormones JH I, JH II, and JH III;
[0025] Figure 2 Morphological characteristic diagrams of the ovaries of Spodoptera frugiperda at levels I-V, where A, ovaries at level I; B, ovaries at level II; C, ovaries at level III; D, ovaries at level IV; E, ovaries at level V. (A'-E') are enlarged views of the local parts of (A-E) respectively. Detailed implementation manners
[0026] The present invention will be described below with reference to the accompanying drawings.
[0027] Example 1: Grading the ovarian development progress of female Spodoptera frugiperda, and the titration ranges of JH I, JH II, and JH III in female insects with ovaries at each level.
[0028] Experimental insect source: Collect Spodoptera frugiperda pupae in the field and bring them back to the laboratory. After the pupae emerge, group the adult Spodoptera frugiperda that emerged on the same day and raise them in a large insect rearing cage with side lengths of 3m×2m×1.6m. The male-female ratio of Spodoptera frugiperda reared in the insect rearing cage is 1:1, and the total number of experimental insects is about 1000. Use 10% honey water by mass fraction as their supplementary nutrition, and replace the fresh 10% honey water in the insect rearing cage every day for them to lay eggs. Observe and record the developmental durations of the eggs, larvae, prepupae, and pupae of Spodoptera frugiperda, and replace the fresh corn leaves every day. The rearing temperature is 28°C±2°C, the relative humidity is 75%±10%, and the photoperiod is 14L:10D.
[0029] Ovarian dissection: Randomly select 20 female adults that emerged on the same day at 8:30 every day and dissect them under a stereomicroscope. The dissection work starts from the first day after the emergence of Spodoptera frugiperda until all the insects die. Observe the ovarian development and yolk deposition, and determine the ovarian development level. The ovarian development is divided into 5 levels: milky white transparent stage (level I), yolk deposition stage (level II), mature waiting stage for egg laying (level III), peak egg laying stage (level IV), and end stage of egg laying (level V).
[0030] Results of the developmental durations of ovaries, eggs, larvae, prepupae, and pupae: By rearing Spodoptera frugiperda in the laboratory, count the developmental durations of ovaries at each level and each insect stage, set 3 replicates, with 200 insects in each group, observe and record the developmental durations of ovaries at each level, as well as the developmental durations of eggs, larvae, prepupae, and pupae. The developmental duration of level I ovaries is 1.52 days, the developmental duration of level II ovaries is 2.75 days, the developmental duration of level III ovaries is 3.25 days, the developmental duration of level IV ovaries is 4.67 days, and the developmental duration of level V ovaries is 5.53 days; the developmental duration of eggs is 6.54 days, the developmental duration of larvae is 11.82 days, the developmental duration of prepupae is 1.85 days, and the developmental duration of pupae is 5.46 days (Table 1).
[0031] Table 1: Developmental durations of Spodoptera frugiperda
[0032]
[0033] A: Determination of juvenile hormone: After determining the ovarian development level of female insects, collect the whole body tissues of the female insects. Weigh 0.1 - 0.5 g of female insects with the same ovarian level, add grinding balls, add 2 mL of mixed solution (0.9% sodium chloride solution: acetonitrile = 1:1), 3 mL of n - hexane, shake for 3 min, then centrifuge at 4000 r / min for 5 min, transfer the supernatant, add another 3 mL of n - hexane, repeat the extraction 2 times. Combine the extracted n - hexane layers into a collection bottle, dry with nitrogen, dissolve and make up to volume with 0.2 mL of acetonitrile - methanol solution, filter through an organic bilayer filter membrane, and analyze using a high - performance liquid chromatography - tandem mass spectrometry. Adopt a gradient program, and the gradient elution is shown in Table 2 as follows:
[0034] Table 2 Liquid chromatography gradient elution program
[0035]
[0036] The mass spectrometry parameters are shown in Table 3:
[0037] Table 3 Mass spectrometry parameters of JHs
[0038]
[0039] B: Classification of ovarian development progress: According to the juvenile hormone titer range, the ovarian development is divided into 5 levels, namely, milky white transparent stage (Level I), vitellogenesis stage (Level II), mature stage awaiting egg - laying (Level III), peak egg - laying stage (Level IV), and late egg - laying stage (Level V).
[0040] During the Level I ovarian stage, the juvenile hormone titer ranges of Spodoptera frugiperda female insects are JHⅠ 0.55 - 0.78 ng / g, JHⅡ 0.81 - 1.00 ng / g, JHⅢ 0.54 - 0.64 ng / g respectively;
[0041] During the Level II ovarian stage, the juvenile hormone titer ranges of Spodoptera frugiperda female insects are JHⅠ 0.87 - 1.76 ng / g, JHⅡ 1.21 - 1.62 ng / g, JHⅢ 1.03 - 1.49 ng / g respectively;
[0042] During the Level III ovarian stage, the juvenile hormone titer ranges of Spodoptera frugiperda female insects are JHⅠ 2.13 - 2.93 ng / g, JHⅡ 2.07 - 2.21 ng / g, JHⅢ 0.95 - 1.01 ng / g respectively;
[0043] During the Level IV ovarian stage, the juvenile hormone titer ranges of Spodoptera frugiperda female insects are JHⅠ 2.38 - 2.68 ng / g, JHⅡ 1.68 - 1.98 ng / g, JHⅢ 0.47 - 0.71 ng / g respectively;
[0044] During the V stage ovarian period, the juvenile hormone titers of female Spodoptera frugiperda insects ranged from 1.44 to 1.50 ng / g for JHⅠ, 1.40 to 1.58 ng / g for JHⅡ, and 1.50 to 1.63 ng / g for JHⅢ.
[0045] C. Main level of ovarian development: Adult fall armyworms from corn fields were collected, and the titers of JHⅠ, JHⅡ, and JHⅢ were tested. The ovarian development level of each individual was determined by the titer of juvenile hormone. The percentage of females at each ovarian development level in the total number of females was counted in turn. The percentage of each level of ovaries was accumulated in order from level V to level I. When the accumulated value reached 50%, the accumulation was stopped, and the lowest ovarian development level among the accumulated ovarian development levels was determined as the main level of ovarian development, which was used to estimate the peak period of the next generation of adults.
[0046] Example 2: Practical operation of fall armyworm prediction technology based on juvenile hormone titer, the specific operation steps are as follows:
[0047] During the corn growing period (April 20, 2024), female samples of Spodoptera frugiperda were collected using a 5-point sampling method in corn fields in Xixiangtang District, Nanning, Guangxi, and the total number of females collected was no less than 100. The female samples were brought back to the laboratory to measure the titers of juvenile hormones JH I, JH II, and JH III of female Spodoptera frugiperda, and the ovarian development level of female Spodoptera frugiperda was determined according to the titer range.
[0048] The proportion of ovaries at each level to the total number of female insects was counted. Then, the percentages of ovaries at each level were accumulated in the order of V and I ovaries. When the accumulated value reached 50%, the accumulation was stopped, and the lowest ovarian development level among the ovarian levels involved in the accumulation was determined as the main ovarian development level. The peak egg-laying period of the current adult and the peak eclosion period of the next generation of adults were calculated according to the following formula.
[0049] Peak spawning period = sample collection date ± | IV level ovarian development period - main level ovarian development period |
[0050] When the main grade of ovarian development is not higher than grade IV, the addition method is used; when the main grade of ovarian development is grade V, the subtraction method is used;
[0051] Peak period of emergence of next generation adults = peak egg-laying period + egg period + larval period + pre-pupa period + pupa period
[0052] The statistical results of the ovarian development level of the collected samples are shown in Table 4. When the percentage values of grade V ovaries to grade I ovaries are accumulated and added to the percentage of grade II ovaries, the cumulative value reaches 66%. Therefore, we determine grade II ovaries as the main level of ovarian development. According to the formula and Table 1, we calculate the peak period of egg-laying and the peak period of adult emergence of the next generation. |Grade IV ovarian development period-main level of ovarian development period|=|Grade IV ovarian period-grade II ovarian period|=4.67 days-2.75 days=1.92 days, the peak period of egg-laying=April 20+1.92=April 22, that is, the peak period of egg-laying is 2 days after the survey date.
[0053] The peak period of emergence of the next generation of adults = April 22 + 6.54 days + 11.82 days + 1.85 days + 5.46 days = May 18. This method completed the survey on April 20, which is about 28 days away from the predicted suitable period for prevention and control of the next generation of adults.
[0054] Verification of the prediction results: On May 18, 115 female adults of Spodoptera frugiperda were collected from corn fields in Xixiangtang District, Nanning, and brought back to the laboratory for ovarian dissection. It was found that the ovaries of 94 female insects were in the II stage of development, indicating that more than 81% of the adults in the sample had emerged in the past two days, indicating that the peak emergence period predicted by this method coincides with the actual peak emergence period of adults.
[0055] Table 4: Titer determination results of juvenile hormones JH I, JH II, and JH III of female fall armyworm (survey date: April 20, 2024)
[0056]
[0057]
[0058]
[0059] Table 5 Record of ovarian development level of female fall armyworm (survey date: April 20, 2024)
[0060]
[0061] Example 3: Practical operation of fall armyworm prediction technology based on juvenile hormone titer, the specific operation steps are as follows:
[0062] During the corn growing period (June 23, 2024), female samples of Spodoptera frugiperda were collected using a 5-point sampling method in corn fields in Xixiangtang District, Nanning, Guangxi, and the total number of females collected was no less than 100. The female samples were brought back to the laboratory to measure the titers of juvenile hormones JH I, JH II, and JH III of female Spodoptera frugiperda, and the ovarian development level of female Spodoptera frugiperda was determined based on the titer range.
[0063] Statistically analyze the proportion of ovaries at each level among the total number of female insects. Then, in the order from level V ovaries to level I ovaries, successively accumulate the percentages of ovaries at each level. When the cumulative value reaches 50%, stop the accumulation, and determine the lowest ovarian development level among the accumulated ovarian levels as the main ovarian development level. Calculate the peak oviposition period of the current generation of adults and the peak emergence period of the next generation of adults according to the following formula.
[0064] Peak oviposition period = Sample collection date ± |Development duration of level IV ovaries - Development duration of the main ovarian development level|
[0065] When the main ovarian development level is not higher than level IV ovaries, addition is used; when the main ovarian development level is level V ovaries, subtraction is used.
[0066] Peak emergence period of the next generation of adults = Peak oviposition period + Egg stage + Larval stage + Pre-pupal stage + Pupal stage
[0067] The statistical results of the ovarian development levels of the collected samples are shown in Table 6. Cumulatively calculate the proportion from level V ovaries to level I ovaries. When the cumulative value reaches 57% at the proportion of level V ovaries, we determine level V ovaries as the main ovarian development level. According to the formula and Table 1, we calculate the peak oviposition period and the peak emergence period of the next generation of adults. |Development duration of level IV ovaries - Development duration of the main ovarian development level| = |Development duration of level IV ovaries - Development duration of level V ovaries| = |4.67 days - 5.53 days| = 0.86 days. Peak oviposition period = June 23 - 0.86 = June 22, that is, the peak oviposition period is 1 day before the survey date.
[0068] Peak emergence period of the next generation of adults = June 22 + 6.54 days + 11.82 days + 1.85 days + 5.46 days = July 18. The survey was completed on June 23 by this method, and there are about 25 days until the appropriate control period of the next generation of adults predicted.
[0069] Verification of the prediction results: On July 18, 109 female Spodoptera frugiperda adults were collected in the corn field in Xixiangtang District, Nanning and brought back to the laboratory for ovarian dissection. It was found that the ovaries of 93 female insects were in the II-level development stage, indicating that more than 85% of the adults in the sample emerged in the recent 2 days, suggesting that the predicted peak emergence period by this method is consistent with the actual peak emergence period of the adults.
[0070] Table 6: Determination results of the titers of juvenile hormones JH I, JH II, and JH III in female Spodoptera frugiperda (Survey date: June 23, 2024)
[0071]
[0072]
[0073]
[0074] Table 7: Record Table of Ovarian Development Levels of Female Fall Armyworms (Investigation Date: June 23, 2024)
[0075]
[0076] Example 4: Practical Operation of the Prediction and Forecast Technology of Fall Armyworms Based on Juvenile Hormone Titer. The specific operation steps are as follows:
[0077] During the maize growth period (August 11, 2024), female fall armyworm samples were collected in a maize field in Xixiangtang District, Nanning, Guangxi, using the five-point sampling method. The total number of female insects collected was not less than 100. The female insect samples were taken back to the laboratory to measure the titers of juvenile hormones JH I, JH II, and JH III in female fall armyworms, and the ovarian development levels of female fall armyworms were determined according to the titer ranges.
[0078] Statistical proportion of ovaries at each level in the total number of female insects. Then, in the order from V-level ovaries to I-level ovaries, the percentages of each level of ovaries were accumulated in turn. When the accumulated value reached 50%, the accumulation was stopped, and the lowest ovarian development level among the ovarian levels involved in the accumulation was determined as the main ovarian development level, and the peak spawning period of the current generation of adults and the peak emergence period of the next generation of adults were calculated according to the following formula.
[0079] Peak spawning period = Sample collection date ± |Duration of IV-level ovarian development - Duration of main ovarian development level|
[0080] When the main ovarian development level is not higher than IV-level ovaries, addition is used; when the main ovarian development level is V-level ovaries, subtraction is used;
[0081] Peak emergence period of the next generation of adults = Peak spawning period + Egg stage + Larval stage + Pre-pupal stage + Pupal stage
[0082] The statistical results of the ovarian development levels of the collected samples are shown in Table 8. The cumulative ratio from V-level ovaries to I-level ovaries reached 60% when the cumulative ratio of IV-level ovaries was reached. Therefore, we determined the IV-level ovaries as the main ovarian development level. According to the formula and Table 1, we calculated the peak spawning period and the peak emergence period of the next generation of adults. |Duration of IV-level ovarian development - Duration of main ovarian development level| = |Duration of IV-level ovaries - Duration of IV-level ovaries| = |4.67 days - 4.67 days| = 0 days, Peak spawning period = August 11 - 0 = August 11, that is, the peak spawning period was on the investigation date.
[0083] Peak emergence period of the next generation of adults = August 11 + 6.54 days + 11.82 days + 1.85 days + 5.46 days = September 6. The investigation was completed on August 11 by this method, and there were about 26 days until the appropriate control period of the next generation of adults predicted.
[0084] Verification of the prediction results: On September 6, 118 female adults of Spodoptera frugiperda were collected from a cornfield in Xixiangtang District, Nanning and brought back to the laboratory for ovarian dissection. It was found that the ovaries of 82 female adults were at the II-level development stage, indicating that more than 69% of the adults in the sample emerged in the past two days, suggesting that the predicted peak emergence period by this method coincides with the actual peak emergence period of adults.
[0085] Table 8: Determination results of the titers of juvenile hormones JH I, JH II, and JH III in female Spodoptera frugiperda (Investigation date: August 11, 2024)
[0086]
[0087]
[0088]
[0089] Table 9: Record table of the ovarian development levels of female Spodoptera frugiperda (Investigation date: August 11, 2024)
[0090]
[0091]
Claims
1. A method for predicting fall armyworm based on juvenile hormone titer range, characterized in that: The following steps are involved: (1) Liquid chromatography-mass spectrometry was used to detect the titers of three juvenile hormones in female Spodoptera frugiperda; (2) Determine the main level of ovarian development based on the measured titers of the three juvenile hormones: count the percentages of females at each ovarian development level to the total number of females, and add up the percentages of each level of ovaries in descending order of ovarian maturity. When the accumulated value reaches 50%, stop accumulating, and determine the lowest ovarian development level among the accumulated ovarian development levels as the main level of ovarian development; (3) The peak egg-laying period of the current generation of adults is predicted by the following formula: Peak spawning period = sample collection date ± | IV grade ovarian development period - ovarian development main level development period | When the main level of ovarian development is not higher than IV grade ovary, addition is used; when the main level of ovarian development is V grade ovary, subtraction is used; (4) The peak period of emergence of the next generation of adults is predicted by the following formula: The peak period of adult emergence of the next generation = the peak period of egg-laying + the sum of the developmental period from the egg stage to the pupal stage.
2. The fall armyworm prediction method based on juvenile hormone titer range according to claim 1, characterized in that: The mass spectrometry conditions of the liquid chromatography-mass spectrometer are as follows: the mass spectrometer used is a triple quadrupole tandem mass spectrometer, an electrospray ion source, multiple reaction monitoring, a positive ion mode, a spray voltage of 5500 eV, a temperature of 550°C, a curtain gas pressure of 0.24 MPa; a collision gas pressure of 0.02 MPa; a collision chamber inlet voltage of 10 V; a collision gas outlet voltage of 15 V; an ion source Gas1: 50 psi; and a Gas2: 50 psi.
3. The fall armyworm prediction method based on juvenile hormone titer range according to claim 1, characterized in that: The separation conditions of the liquid chromatography are as follows: C18 chromatographic column: 100 mm×2.1 mm, 1.8 μm; chromatographic column temperature 30° C., injection volume 15 μL; mobile phase: A is 0.1% formic acid water, B is 0.1% formic acid acetonitrile.
4. The fall armyworm prediction method based on juvenile hormone titer range according to claim 1, characterized in that: The ovarian development level is divided into 5 levels, namely, milky white and transparent stage, yolk deposition stage, mature and ready-to-lay stage, peak egg-laying stage and final egg-laying stage; among them, in the milky white and transparent stage, the juvenile hormone titer ranges of female fall armyworms are JHⅠ0.55-0.78 ng / g, JHⅡ0.81-1.00 ng / g, and JHⅢ0.54-0.64 ng / g, respectively; in the yolk deposition stage, the juvenile hormone titer ranges of female fall armyworms are JHⅠ0.87-1.76 ng / g, JHⅡ1.21-1.62 ng / g, and JHⅢ1.03-1.49 ng / g, respectively; in the mature and ready-to-lay stage, the juvenile hormone titer ranges of female fall armyworms are JHⅠ0.87-1.76 ng / g, JHⅡ1.21-1.62 ng / g, and JHⅢ1.03-1.49 ng / g, respectively The juvenile hormone titers ranged from JHⅠ2.13 to 2.93 ng / g, JHⅡ2.07 to 2.21 ng / g, and JHⅢ0.95 to 1.01 ng / g, respectively; during the peak egg-laying period, the juvenile hormone titers of female fall armyworms ranged from JHⅠ2.38 to 2.68 ng / g, JHⅡ1.68 to 1.98 ng / g, and JHⅢ0.47 to 0.71 ng / g, respectively; during the late egg-laying period, the juvenile hormone titers of female fall armyworms ranged from JHⅠ1.44 to 1.50 ng / g, JHⅡ1.40 to 1.58 ng / g, and JHⅢ1.50 to 1.63 ng / g, respectively.
5. The fall armyworm prediction method based on juvenile hormone titer range according to claim 1, characterized in that: The detailed values of the developmental periods of each level of ovaries are: 1.52 days for the milky white and transparent stage, 2.75 days for the yolk deposition stage, 3.25 days for the mature and ready-to-lay stage, 4.67 days for the peak spawning stage, and 5.53 days for the late spawning stage.
6. The fall armyworm prediction method based on juvenile hormone titer range according to claim 1, characterized in that: The developmental period from the egg stage to the pupal stage is specifically as follows: 6.54 days for the egg stage, 11.82 days for the larvae, 1.85 days for the prepupae, and 5.46 days for the pupae.