Method for regulating the growth of bombyx mor and improving cocoon yield

Abstract

The application discloses a method for regulating the growth of silkworms and improving cocoon yield, and belongs to the technical field of silkworm production. The method comprises the following steps: 24 hours after the silkworms at the third instar start to grow, natural juvenile hormone solution is added dropwise on the surface of fresh mulberry leaves, and the silkworms are fed after being naturally dried; the natural juvenile hormone is juvenile hormone I, juvenile hormone II or juvenile hormone III, and the concentration is 1.6-16 ng / mL. The method can prolong the fifth instar period of the silkworms and the time from the third instar to cocoon formation, promote the accumulation of nutrients, increase the weight of the silkworms and the cocoon weight, and is beneficial to improving the cocoon quality. The method is simple in operation, low in dosage, high in safety, and can provide a new technical approach for the development and utilization of natural juvenile hormone in silkworm production.

Description

Technical Field

[0001] This invention relates to the fields of silkworm breeding and insect endocrine regulation technology, specifically to a method for regulating silkworm growth and improving cocoon quality based on the physiological titer of natural juvenile hormone in the third instar of silkworms. Background Technology

[0002] The silkworm (Bombyx mori) is an important economic insect, and its silk is a crucial raw material for the silk industry. The growth and development of silkworms, as well as their cocoon yield and quality, directly impact the economic benefits of the sericulture and silk industries. With the development of modern sericulture, improving silkworm growth efficiency, increasing cocoon yield, and enhancing cocoon quality have become important research directions in silkworm farming.

[0003] Currently, researchers have conducted various technical studies to improve silkworm production performance, including optimizing the nutritional components of mulberry leaves, improving rearing environmental conditions, and breeding superior silkworm varieties. However, these methods often suffer from high input costs, significant susceptibility to environmental factors, unstable control effects, and long implementation cycles. Therefore, how to promote growth and development and improve cocoon yield and quality by regulating the physiological state of silkworms has become an urgent problem to be solved in the silkworm farming field.

[0004] Juvenile hormone (JH) is an important endogenous hormone in insects that regulates growth, development, molting, and metamorphosis, playing a crucial role in maintaining larval status, promoting nutrient accumulation, and regulating developmental processes. Studies have shown that appropriate levels of JH can prolong the larval stage and increase nutrient accumulation, thereby affecting individual growth, development, and production performance. Currently, the application of JH in silkworm production mainly focuses on the artificial synthesis of JH analogs, while research on the application of natural JH—JH I (JH I), JH II (JH II), and JH III (JH III)—is relatively limited. Furthermore, existing technologies have not fully utilized the physiological titers of natural JH in silkworms for precise regulation to effectively improve silkworm growth, development, and production performance. Therefore, this invention provides a method for regulating silkworm growth and development, promoting nutrient accumulation, and increasing cocoon yield by supplementing with JH I, JH II, or JH III, based on the physiological titers of natural JH in the third instar of silkworms, offering a new technical approach for regulating silkworm production performance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for regulating silkworm growth and improving cocoon quality based on the physiological titer of natural juvenile hormones in the third instar of silkworms. This method can prolong the nutrient accumulation period of silkworm larvae, promote silkworm weight gain, increase cocoon weight, and help maintain and improve cocoon quality, thereby improving silkworm production performance and the economic benefits of sericulture.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for regulating silkworm growth and improving cocoon quality based on the physiological titer of natural juvenile hormones involves adding a natural juvenile hormone solution to the surface of fresh mulberry leaves within 24 hours after the third instar of silkworms, allowing them to air dry naturally, and then feeding the silkworms with the leaves. The natural juvenile hormones are selected from juvenile hormone I, juvenile hormone II, or juvenile hormone III.

[0008] The concentration of the natural juvenile hormone solution is 1.6–16 ng / mL, and the amount added is 1–3 μL per silkworm.

[0009] The natural juvenile hormone is juvenile hormone III. The concentration of juvenile hormone III is 16 ng / mL.

[0010] The natural juvenile hormone solution uses acetonitrile as a solvent.

[0011] The amount added was 2 μL per silkworm.

[0012] The silkworm in question is the Liangguang No. 2 variety.

[0013] The application of natural juvenile hormones in the preparation of growth regulators for silkworms, wherein the natural juvenile hormones are selected from juvenile hormone I (JH I), juvenile hormone II (JH II), or juvenile hormone III (JH III), and are used to prolong the larval development period, increase the weight of silkworm cocoons, and improve the quality of silkworm silk by feeding them with mulberry leaves during the third instar of silkworms.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Promotes silkworm growth and nutrient accumulation: Juvenile hormone treatment can moderately prolong the larval stage and increase the time for nutrient accumulation, thereby promoting silkworm growth and increasing silkworm weight.

[0016] 2. Increase silkworm cocoon yield: After treatment with natural juvenile hormones, the average cocoon weight of silkworms is increased, which is conducive to improving the economic benefits of sericulture.

[0017] 3. Improved silkworm cocoon quality: The treated silkworm cocoons showed good performance in terms of quality indicators such as cocoon silk yield, unwinding silk length, unwinding rate, cocoon loading rate, and silk fineness, indicating that the natural juvenile hormone treatment has the application potential to improve the overall economic traits of silkworm cocoons.

[0018] 4. Application safety: It uses natural juvenile hormones for regulation, with low treatment doses, is environmentally friendly, and is suitable for large-scale promotion and application. Detailed Implementation

[0019] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0020] Example

[0021] This embodiment aims to study the effects of different types of natural juvenile hormones and their concentrations on the growth and development of silkworms and the quality of their cocoons.

[0022] The tested silkworm variety was Liangguang No. 2, and the tested natural juvenile hormones were JH I, JH II, and JH III, with acetonitrile as the solvent. Based on the physiological titers of natural juvenile hormones in the third instar of silkworms, treatment concentrations of 1x (1.6 ng / mL) and 10x (16 ng / mL) were set. The experiment consisted of eight treatment groups: control group, control group, JHⅠ-1 group, JHⅡ-1 group, JHⅢ-1 group, JHⅠ-10 group, JHⅡ-10 group, and JHⅢ-10 group. The control group received normal feeding without treatment. The control group was fed an equal volume of acetonitrile solvent. The treatment groups were: JHⅠ-1 group (fed at 1x physiological titer JHⅠ), JHⅡ-1 group (fed at 1x physiological titer JHⅡ), JHⅢ-1 group (fed at 1x physiological titer JHⅢ), JHⅠ-10 group (fed at 10x physiological titer JHⅠ), JHⅡ-10 group (fed at 10x physiological titer JHⅡ), and JHⅢ-10 group (fed at 10x physiological titer JHⅢ). Each treatment group had four biological replicates, with 20 silkworms per replicate.

[0023] Treatment method: The treatment should be carried out within 24 hours after the third instar of silkworms. Use a micropipette to draw 2 μL of juvenile hormone solution and drop it onto the surface of fresh mulberry leaves. After air drying, feed the silkworms immediately.

[0024] After treatment, the weight of each silkworm was measured every 3 days using an electronic balance with an accuracy of 0.01 g. The time for the fifth instar and the total time from the third instar to cocooning were recorded for each group of silkworms. After the silkworms completed pupation, abnormal individuals such as those with thin cocoons or inferior cocoons were removed. Each cocoon was then weighed using an analytical balance with an accuracy of 0.001 g, and the average cocoon weight was calculated. Mature cocoons were selected and sent to the Guangxi Zhuang Autonomous Region Product Quality Inspection and Research Institute for silk quality testing according to GB / T 15268-2024 standard. The weight of each group of silkworms was measured six times, and the results are shown in Table 1.

[0025] Table 1. Changes in average body weight of silkworms after treatment with different natural juvenile hormones.

[0026] Unit: g

[0027]

[0028] Table 1 shows that the weight of silkworms in all treatment groups gradually increased with development. At the sixth weighing, all three natural juvenile hormone treatments promoted weight gain, with the 10-fold physiological titer group showing a greater effect than the 1-fold physiological titer group. Compared with the control group, the weight of the 1-fold physiological titer treatment group increased by 3.17%–3.66%, and the weight of the 10-fold physiological titer treatment group increased by 4.39%–5.37%. These results indicate that natural juvenile hormone treatment can promote nutrient accumulation and increase the weight of silkworms.

[0029] The time from the fifth instar to cocoon formation was measured for each treatment group, and the elongation rate was calculated. The results are shown in Table 2.

[0030] Table 2. Effects of different natural juvenile hormone treatments on the developmental stages of silkworms.

[0031]

[0032] Table 2 shows that the time from the fifth instar to cocooning in the control group was 6 days and 15 hours, and the time from the third instar to cocooning was 15 days and 8 hours; there was no significant difference between the control group and the CK group. The extension rate of the fifth instar to cocooning time in the 1x physiological titer treatment group was 6.92%–22.64%, and the extension rate from the third instar to cocooning time was 4.08%–5.43%. The effect was more significant in the 10x physiological titer treatment group, with the extension rate of the fifth instar to cocooning time reaching 50.31%–54.09%, and the extension rate from the third instar to cocooning time reaching 24.46%–27.17%. This indicates that natural juvenile hormone treatment can effectively delay the metamorphosis of silkworms and prolong the feeding and nutrient accumulation time of larvae.

[0033] After the silkworms completed pupation, abnormal individuals such as thin cocoons and inferior cocoons were removed. Each cocoon in each group was weighed using an analytical balance with an accuracy of 0.001 g. The average cocoon weight of each group was calculated, and the cocoon weight gain rate was calculated with the blank group as a control. The results are shown in Table 3.

[0034] Table 3. Effects of different natural juvenile hormone treatments on the average cocoon weight of silkworms.

[0035]

[0036] Table 3 shows that the average cocoon weight of each JH treatment group was higher than that of the blank control group and the CK group. The weight gain rate of the 1x concentration treatment group was 2.24%-8.63%, and the cocoon weight of the 10x concentration treatment group was all above 1.87g, with a weight gain rate of 12.28%-13.01%.

[0037] The above results indicate that the natural juvenile hormone treatment method described in this invention can significantly increase the average cocoon weight of silkworms and has a significant effect on increasing cocoon production.

[0038] To evaluate the quality level of silkworm cocoons treated according to the present invention, quality indicators were tested on each group of silkworm cocoons. The test items included cleanliness, cocoon silk yield, unwinding silk length, unwinding rate, cocoon loading rate, and cocoon silk fineness. The test results were compared with the quality indicators of conventionally raised silkworm cocoons of the same variety reported in published literature. The results are shown in Table 4.

[0039] Table 4. Results of silkworm cocoon quality testing after treatment with natural juvenile hormones

[0040]

[0041] As shown in Table 4, compared with the conventional feeding control area reported in published literature, all silkworm cocoon quality indicators in the experimental area treated with the natural juvenile hormone of this invention were improved. Regarding cocoon quality, the experimental area achieved or exceeded the levels reported in published literature in terms of cleanliness score, cocoon silk yield, unwound silk length, unwound rate, cocoon loading rate, and silk fineness. Specifically, the unwound rate increased by 16.48%, and the silk fineness increased by 15.03%. This indicates that JH treatment can effectively improve silkworm cocoon quality.

[0042] In summary, this invention, based on the physiological titer of natural juvenile hormones in silkworms, regulates the growth and development of silkworms during the third instar by feeding them natural juvenile hormones JH I, JH II, or JH III. Experimental results show that this method can prolong the time from the third instar to cocooning and the fifth instar, increase the time for nutrient accumulation, promote silkworm weight gain, increase cocoon weight, and help maintain and improve cocoon quality. This method is simple to operate, requires small dosages, and is easy to implement, providing a new technical approach for the application of natural juvenile hormones in silkworm production, and has good prospects for widespread application.

Claims

1. A method for regulating silkworm growth and increasing cocoon yield, characterized in that: Within 24 hours after the silkworms reach the third instar, a natural juvenile hormone solution is dripped onto the surface of fresh mulberry leaves, which are then allowed to air dry before being fed to the silkworms. The natural juvenile hormone is selected from juvenile hormone I, juvenile hormone II, or juvenile hormone III.

2. The method according to claim 1, characterized in that: The concentration of the natural juvenile hormone solution is 1.6–16 ng / mL, and the amount added is 1–3 μL per silkworm.

3. The method according to claim 1, characterized in that: The natural juvenile hormone mentioned is juvenile hormone III.

4. The method according to claim 3, characterized in that: The concentration of juvenile hormone III was 16 ng / mL.

5. The method according to claim 3, characterized in that: The natural juvenile hormone solution uses acetonitrile as a solvent.

6. The method according to any one of claims 1-5, characterized in that, The amount added was 2 μL per silkworm.

7. The method according to any one of claims 1-5, characterized in that, The silkworm in question is the Liangguang No. 2 variety.

8. The application of natural juvenile hormone in the preparation of growth regulators for silkworms, characterized in that, The natural juvenile hormones are selected from juvenile hormone I, juvenile hormone II, or juvenile hormone III, and are used to prolong the larval development period, increase the weight of silkworm cocoons, and improve the quality of silk by feeding silkworms with mulberry leaves during the third instar.

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