Method for efficiently producing Trichogramma myxomycetes, the dominant natural enemy of soybean borer, by utilizing castor silkworm eggs

Abstract

The invention provides a method for efficiently producing trichogrammatids, a dominant natural enemy of soybean borer, by utilizing castor silkworm eggs. The method comprises the following steps: obtaining trichogrammatids and fresh mature castor silkworm eggs; parasitizing castor silkworm eggs for the first time, taking fresh mature castor silkworm eggs, inoculating them with bees at a bee-egg ratio of 2:1-6:1 at a temperature of 26±1°C, a relative air humidity of 90±3%, and a 14L:10D ratio for 24-48 hours, removing bee species, placing the parasitized eggs in an environment of a temperature of 26±1°C, a relative air humidity of 90±3%, and a 14L:10D ratio for development, and obtaining offspring bees that have eclosed from parent host eggs; and continuously breeding offspring bees with the offspring bees that have eclosed from the parent host eggs and fresh mature castor silkworm eggs, wherein the bee inoculation environment is 26±1°C, a relative air humidity of 75±3%, and a 14L:10D ratio for 24-48 hours, then removing the bee species, and allowing the offspring bees to begin development in an environment of 26±1°C and a relative air humidity of 75±3%. The method of the present invention can be used to obtain mature eggs of the ricinus silkworm in an efficient and high-quality manner, and is successfully applied to the production of natural enemy insects.

Description

Technical Field

[0001] The invention belongs to the technical field of biological control of agricultural pests, and particularly relates to a method for efficiently producing Trichogramma myxomycetes, the dominant natural enemy of soybean borer, by utilizing ricinus silkworm eggs. Background Art

[0002] Trichogrammatids are the most widely used natural enemy insects in biological control in my country. They can be mass-produced in factories and are effective in controlling lepidopteran pests. Currently, the intermediate hosts for breeding Trichogrammatids mainly include large and small eggs. The eggs of Antheraea pernyi (large eggs) are used to breed Trichogrammatids ( Figure 1 ), each tussah silkworm egg is parasitized by 70-90 trichogrammatids. Since the trichogrammatid species that can be bred using tussah silkworm eggs are currently only a few strains of pine caterpillar trichogrammatids (Trichogramma dendrolimi) and yellow stem borer trichogrammatids (Trichogramma chilonis), most trichogrammatid species do not parasitize tussah silkworm eggs, or cannot successfully hatch after parasitizing tussah silkworm eggs, this has become a bottleneck problem restricting its further promotion, application and development; using artificially propagated rice moth (Corcyra cephalonica) eggs (small eggs) to breed trichogrammatids ( Figure 2 ), each rice moth egg can parasitize 1-2 trichogrammatids, which leads to the problems of high cost and low production efficiency of factory breeding.

[0003] The soybean borer (Leguminibora glyciniborella) is also known as the soybean borer. Its larvae are commonly known as small red worms. Its main way of causing harm is to bore into the bean pods. Under normal circumstances, the damage rate is 10% to 20%, and in severe cases it can reach more than 50%. It poses a serious threat to soybean yield and quality and is one of the important pod-boring pests on soybeans in the three northeastern provinces.

[0004] Developing efficient and low-cost factory-based breeding techniques for the Trichogramma leucaniae, an obligate parasitoid of the soybean borer, is crucial. Currently, domestic breeding of Trichogramma leucaniae using tussah silkworm eggs is unstable and inefficient. Previous studies have shown that when artificially breeding Trichogramma leucaniae using tussah silkworm eggs for multiple generations, parasitism is most effective only in the fourth generation, with subsequent generations experiencing decreasing effectiveness. Therefore, exploring new, advantageous intermediate hosts is crucial for breeding Trichogramma leucaniae.

[0005] The ricin silkworm (Samia cynthia ricini), a member of the Lepidoptera family, is a polymorphous, complete silk-spinning insect with no diapause in temperate and tropical regions. Its primary diet is ricin silkworms, Ailanthus altissima leaves, and cassava leaves. Compared to tussah silkworms, ricin silkworms eliminate geographical restrictions and overwintering bottlenecks, providing fresh intermediate host eggs for industrial breeding of trichogrammatids year-round. my country has successfully used ricin silkworm eggs to breed trichogrammatids (Trichogramma evanescens), pine caterpillar trichogrammatids (Trichogramma dendrolimi), and pseudo-Australian trichogrammatids (Trichogramma confusum). Using castor silkworm eggs to breed bees, each egg can produce 20 to 30 bees, and the bee breeding scale is between the "big and small eggs" mentioned above, such as tussah silkworm eggs and rice moth eggs. Although using castor silkworm eggs to breed trichogrammatids has unique development and utilization advantages, there are no reports on the development and utilization of other trichogrammatid species. The breeding habits of different species of trichogrammatids vary greatly. Different species of trichogrammatids, different parasitic objects, and different breeding conditions will significantly affect the breeding effect of trichogrammatids.

[0006] Research has found that there are currently few intermediate host species available for breeding Trichogrammatids. Traditional breeding methods include using rice moth eggs and tussah silkworm eggs. However, the high cost of breeding rice moth eggs (small eggs) makes them unsuitable for factory production. Using tussah silkworm eggs (large eggs) to breed Trichogrammatids is more widely used, but only a few strains, such as pine caterpillar Trichogrammatids and yellow stem borer Trichogrammatids, have shown good results. Other Trichogrammatid species do not parasitize tussah silkworm eggs or fail to successfully emerge after parasitizing them. The unstable parasitism rate of Trichogrammatids on tussah silkworm eggs and the cumbersome domestication process have become bottlenecks hindering their further application.

[0007] When using castor silkworm eggs to breed bees, if the eggs of newly emerged female castor silkworm moths are collected according to conventional methods in the industry, the quality of the eggs is not ideal. The proportion of immature eggs such as shriveled eggs and green eggs is high, and the utilization efficiency of the host insect raw materials is low. Therefore, it is necessary to explore new ways to efficiently obtain eggs to improve egg utilization.

[0008] Therefore, it is necessary to find an efficient breeding method for Trichogramma stickymatis. Summary of the Invention

[0009] To address the aforementioned technical issues in the prior art, the present invention utilizes a novel intermediate host, the ricinus silkworm eggs, to breed Trichogrammatis, allowing more individuals to successfully break through the ricinus silkworm egg shells, form cavities, and continue to lay offspring on the ricinus silkworm eggs. This allows the Trichogrammatis to maintain a relatively stable population, ultimately enabling independent and continuous breeding of Trichogrammatis on ricinus silkworm eggs.

[0010] A method for efficiently breeding trichogrammatids using ricinus silkworm eggs comprises the following steps:

[0011] S1. Obtain Trichogramma myxomycetes and fresh mature ricinus silkworm eggs;

[0012] S2. The first parasitization of ricinus silkworm eggs by trichogrammatids by sticky insects is carried out, wherein fresh mature ricinus silkworm eggs treated in step (1) are taken, and the eggs are inoculated with bees in a ratio of 2:1 to 6:1 at a temperature of (26±1)°C and a relative humidity of (90±3)%, a photoperiod of 14L:10D, i.e., 14 hours of light and 10 hours of darkness, for 24 to 48 hours. The bees are then removed, and the parasitized eggs are placed in an environment with a temperature of (26±1)°C and a relative humidity of (90±3)%, a photoperiod of 14L:10D, i.e., 14 hours of light and 10 hours of darkness, to develop, and obtain offspring bees that have emerged from the parent host eggs;

[0013] S3. Continuous breeding of trichogrammatid wasps: The offspring bees that have emerged from the parent host eggs in step (2) and the fresh mature ricinus silkworm eggs obtained in step (1) are used to continue breeding the bees. The bee breeding environment is: (26±1)℃, relative air humidity (75±3)%, and the photoperiod is 14L:10D. The bee breeding lasts for 24 to 48 hours, and then the bee species are removed. The offspring bees begin to develop in the development environment: (26±1)℃, relative air humidity (75±3)%.

[0014] Furthermore, the method for obtaining the fresh mature castor silkworm eggs described in S1 is to treat the newly emerged female castor silkworm moth at 45°C for 2 hours to allow the eggs in its body to develop and mature rapidly, and then perform a laparotomy and wash with water to obtain the fresh mature castor silkworm eggs.

[0015] Furthermore, the method for obtaining the fresh mature castor silkworm eggs described in S1 is to treat the newly emerged female castor silkworm moths at 4°C for 3-7 days, perform a laparotomy and wash them with water to obtain the fresh mature castor silkworm eggs.

[0016] Furthermore, the fresh mature castor silkworm eggs in S1 are controlled not to be completely dried and do not contain water droplets on the surface. For example, the surface moisture content of each fresh mature castor silkworm egg in S1 is controlled to be 5.26%-11.13%.

[0017] Furthermore, the method also includes S4, evaluating the quality of the offspring trichogrammatids bred from ricinus silkworm eggs, and using rice moth eggs to breed one generation for rejuvenation when the offspring do not meet the breeding expectations.

[0018] Furthermore, the bee species quality assessment includes assessing one or more of the following: parasitism rate, emergence rate, number of bees per egg, and female-to-female ratio.

[0019] In a specific embodiment, the original population of the sticky insect trichogrammatid described in S1 is obtained by trapping and collecting in the wild, and after species identification, the population is conserved using rice moth eggs for subsequent processing steps.

[0020] The beneficial effects of the present invention are:

[0021] Compared with the use of tussah silkworm eggs, the castor silkworm eggs used in the present invention have lower costs, can increase the parasitism rate of the sticky insect trichogrammatid by 12 percentage points, and can increase the emergence rate by 24 percentage points. In the case of multi-generation reproduction, due to the improved adaptability, the above values can be further improved with each generation increasing. At the same time, the efficient parasitic characteristics reduce the loss of raw materials and save costs.

[0022] This method proposes a method for artificially processing ricinus silkworms to quickly obtain mature eggs. Compared with conventional methods, this method improves host egg quality and saves time. It also facilitates flexible arrangements for natural enemy insect breeding based on user needs. Furthermore, a safer and more efficient host egg sorting device has been designed, saving costs for factory-scale production.

[0023] Castor silkworms have no diapause period and can grow and develop year-round as long as they have sufficient castor leaves. We have achieved a year-round supply of castor leaves, ensuring the reproduction and development of castor silkworms, overcoming the technical challenge of tussah silkworms needing to break diapause. Furthermore, castor silkworms are a widely grown insect, bred in Africa, Europe, and Asia, while tussah silkworms are only bred in parts of East Asia. Therefore, castor silkworm breeding bees are more readily available.

[0024] Castor silkworm eggs can efficiently breed Trichogramma sticky wasps, and their parasitic effect increases with each generation without any decline.

[0025] Compared with the eggs of rice moth and tussah silkworm, the trichogrammatid wasp bred from ricinus silkworm eggs is more efficient in parasitizing the eggs of the target pest soybean borer.

[0026] The present invention has discovered a method for obtaining mature eggs of the ricinus silkworm with high efficiency and quality, and has been successfully applied to the production of natural enemy insects.

[0027] Currently, the suitability of Trichogrammatus mykiss to parasitize ricinus silkworm eggs is unknown, and there are no reports on the use of ricinus silkworm eggs to control Trichogrammatus mykiss, the dominant natural enemy of soybean borer. Our preliminary testing has shown that Trichogrammatus mykiss can successfully parasitize ricinus silkworm eggs and produce bees from them. This provides technical support for the future large-scale breeding of Trichogrammatus to control agricultural pests and is of great significance for guiding the development and utilization of Trichogrammatus for biological control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the existing technology of the production process of tussah eggs (large eggs) breeding bees;

[0029] Figure 2 This is the existing process for producing bees from rice moth eggs (small eggs);

[0030] Figure 3 This is a flow chart of an embodiment of this patent. DETAILED DESCRIPTION

[0031] The present invention is further explained below with reference to the following examples, but the examples do not limit the present invention in any form.

[0032] Example 1: High Humidity Ricinus Coconut Silkworm Eggs Breeding Trichogramma Mythimna

[0033] 1. Experimental Materials

[0034] Bee species: Trichogramma stickyii bred from rice moth eggs.

[0035] Host eggs: fresh mature eggs of ricinus silkworms (on the day of eclosion), which were cut open and washed with water but not completely dried and without water droplets on the surface. The surface moisture content of each egg was 5.26%-11.13%.

[0036] 2. Experimental Environment

[0037] Experimental group: relative humidity (90±3)%, temperature (26±1)℃, photoperiod 14L:10D.

[0038] Control group 1: relative humidity (80±3)%, temperature (26±1)℃, photoperiod 14L:10D.

[0039] Control group 2: relative humidity (75±3)%, temperature (26±1)℃, photoperiod 14L:10D.

[0040] 3. Experimental Methods

[0041] 300 Trichogrammatids within 8 hours of their initial emergence from rice moth eggs were introduced into a test tube containing 100 highly humidified ricinus silkworm eggs (bee-egg ratio 3:1), and were treated with bees separately under the experimental environment described in "2.". After 24 hours, the female bees were removed, and the parasitized eggs were placed in an incubator and bred separately under the experimental environment described in "2." The quality of the bee species was evaluated by statistically analyzing indicators such as the parasitism rate and emergence rate of the offspring.

[0042] <![CDATA[90±3% 湿度 ]]> <![CDATA[80±3% 湿度 ]]> <![CDATA[75±3% 湿度 <!-- 3 -->]]> Parasitism rate (%) 69.5 56.2 52 Emergence rate (%) 70.6 55.1 50.3 Number of feathering holes 2.13 1.58 1.08

[0043] The results showed that the conventional bee-receiving and development humidity was about 75%, and when the sticky-nematode trichogrammatid parasitized the ricinus silkworm eggs, the parasitism rate, emergence rate, and number of emergence holes at a humidity of 75% could not meet the requirements for efficient reproduction. Even if the bee-receiving and development humidity was increased to about 80%, the parasitism rate, emergence rate, and number of emergence holes did not show a significant improvement compared with the 75% humidity state. However, under the relative humidity of (90±3)% specified in the present invention, combined with the temperature, photoperiod, bee-egg ratio, and inoculation time described in the present invention, the parasitism rate, emergence rate, and number of emergence holes were significantly improved, which is conducive to the efficient breeding of the sticky-nematode trichogrammatid.

[0044] Example 2: Continuously breeding Trichogramma separata populations using ricin silkworm eggs

[0045] 1. Experimental Materials

[0046] Bee species: Trichogramma stickyii bred from rice moth eggs.

[0047] Experimental group: Host eggs: fresh mature eggs of ricinus silkworms (on the day of eclosion) that were cut open and washed but not completely dried and without water droplets on the surface, with the surface moisture content of each egg being 5.26%-11.13%.

[0048] Comparative Group 1: Host eggs: fresh mature tussah eggs (on the day of eclosion) that were cut open and washed but not completely dried and had no water droplets on the surface. The surface moisture content of each egg was 6.15%-9.06%.

[0049] 2. Experimental environment and methods

[0050] Fifteen fully mated female trichogrammatids within 8 hours of eclosion from oryzae eggs were introduced into a test tube containing five ricinus silkworm eggs or five tussah silkworm eggs described in Example "1" (both at a bee-to-egg ratio of 3:1). The tubes were then placed in a climate chamber at a temperature of 26°C, a relative humidity of 90%, and a light intensity ratio of 14:10. After 24 hours, the female bees were removed, and the parasitized eggs were placed in an environment at a temperature of (26±1)°C, a relative humidity of (90±3)%, and a photoperiod of 14:10. The resulting progeny, which eclosed from the parental host eggs, were designated the F1 generation. The quality of the bee species was assessed by statistically analyzing the parasitism rate and eclosion rate of the progeny.

[0051] For subsequent breeding, F1-generation bees are used to provide castor silkworm eggs at a bee-egg ratio of 3:1. The bee-inoculation environment is (26±1)°C, relative humidity (75±3)%, and a photoperiod of 14 L / 10 D. This inoculation lasts for 24 hours, after which the bees are removed and the offspring begins to develop. The development environment is (26±1)°C, relative humidity (75±3)%, and a photoperiod of 14 L / 10 D. Generations are then bred.

[0052] The offspring of Trichogrammatids (Trichogrammatids) bred from ricinus silkworm eggs are randomly inspected generation by generation, and the quality of the bee species is assessed based on indicators such as parasitism rate, emergence rate, number of bees per egg, and female-to-female ratio. If the quality of the offspring declines, they should be promptly rejuvenated by breeding a new generation with eggs from the rice moth.

[0053] 4. Experimental Results

[0054]

[0055] 5. Results Analysis

[0056] Our experimental results show that Trichogrammatis bred from castor silkworm eggs has a stronger parasitic ability than Trichogrammatis bred from tussah silkworm eggs. We bred Trichogrammatis bred on two intermediate hosts for three generations and found that the parasitism rate of Trichogrammatis bred from castor silkworm eggs was about 10% higher than that of Trichogrammatis bred from tussah silkworm eggs in each generation. The advantage in emergence rate was even more significant, and the emergence rate advantage increased with each generation. Therefore, Trichogrammatis bred from castor silkworm eggs has a greater advantage than Trichogrammatis bred from tussah silkworm eggs.

[0057] Example 3 Efficiently Obtaining Host Ricinus Silkworm Eggs

[0058] 1. Experimental Materials

[0059] Indoor propagation of newly emerged female moths of castor silkworm.

[0060] 2. Experimental Environment

[0061] The temperature was (26±1)℃, the relative humidity was (70±3)%, and the photoperiod was 14L:10D.

[0062] 3. Experimental Methods

[0063] Experimental group 1: Heating treatment: newly emerged female ricinus silkworm moths were placed in a 45°C oven for 2 h, then dissected and washed with water to obtain fresh mature ricinus silkworm eggs;

[0064] Experimental group 2: Refrigeration treatment: newly emerged female moths were refrigerated at 4°C for 3-7 days, then dissected and washed with water to obtain fresh mature ricinus silkworm eggs;

[0065] Comparative group 1: conventional treatment: female moths were collected at room temperature at 0 and 2 hours, and their abdomens were cut open and washed with water to obtain fresh mature ricinus silkworm eggs.

[0066] Finally, the percentage of green eggs, deflated eggs, etc. in the total number of eggs in the laparotomy water-washed eggs after different treatments was investigated.

[0067] 4. Experimental Results

[0068]

[0069] 5. Results Analysis

[0070] Mature eggs from female castor silkworm moths collected at room temperature for 0 hours represent the baseline level of mature castor silkworm eggs, and are also the standard method for collecting castor silkworm eggs in this field. Under this treatment, the mature egg ratio and number of mature eggs are the lowest. After 2 hours at room temperature, the mature egg ratio and number of mature eggs do not increase significantly. Eggs in the refrigerated development group gradually mature after 72 to 168 hours, but the mature egg ratio and number of mature eggs after 2 hours of refrigeration are no better than those obtained after 2 hours at room temperature. In the warmed development group, over 90% of mature eggs were obtained in just 2 hours, and the number of mature eggs was greater, indicating that warmed development is more effective and efficient. However, after 4 hours of warmed development, the mature egg ratio and number of mature eggs decreased. In summary, warmed development allows for efficient collection of castor silkworm host eggs, saving production time and increasing the maturation rate and number of host eggs.

[0071] Example 4: Parasitism of soybean borer eggs by trichogrammatids bred from castor silkworm eggs

[0072] 1. Experimental Materials

[0073] Bee species: Trichogramma stickyii bred from ricin silkworm eggs.

[0074] Host eggs: soybean borer eggs.

[0075] 2. Experimental Environment

[0076] Temperature (26±1)℃, relative humidity (75±3)%, photoperiod 14L:10D.

[0077] 3. Experimental Methods

[0078] Experimental group: F1 generation of trichogrammatids bred from castor silkworm eggs, obtained as in Example 1.

[0079] Comparative Group 1: The F1 generation (obtained by the same method as in Example 2 and Comparative Group 1) progeny bees were obtained by acclimating Trichogramma myxomycetes on tussah eggs for testing.

[0080] Comparative group 2: The F1 generation of Trichogramma stickyma bred from rice moth eggs was obtained by inoculating bees on rice moth eggs at a bee-egg ratio of 1:1.

[0081] Every afternoon, adult soybean borers were collected from the soybean experimental field. After they laid eggs in the inoculation cups, Trichogrammatids bred from ricinus silkworm eggs were introduced for parasitism.

[0082] The inoculated cups were placed under the environmental conditions of 26±1°C, 75±3% RH, L:D=14:10 and cultured. The parasitic status of the eggs was investigated after 6 days.

[0083] 4. Experimental Results

[0084]

[0085] 5. Results Analysis

[0086] From the experimental results, we can see that the number of parasitic eggs of the target pest soybean borer parasitized by the trichogrammatids bred by castor silkworm eggs is significantly higher than that of the trichogrammatids bred by rice moth eggs and tussah silkworm eggs. The number of parasitic eggs of the trichogrammatids bred by castor silkworm eggs is significantly higher than that of the trichogrammatids bred by rice moth eggs and tussah silkworm eggs. This indicates that castor silkworm eggs can be used as the best intermediate host for the control of soybean borer.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for efficiently breeding Trichogramma separata using ricinus silkworm eggs, characterized in that: The method comprises the following steps: S1. Obtain Trichogramma myxomycetes and fresh mature ricinus silkworm eggs; S2. The first parasitization of ricinus silkworm eggs by trichogrammatids is performed, wherein fresh mature ricinus silkworm eggs treated in step (1) are taken, and the eggs are inoculated with bees at a bee-egg ratio of 2:1 to 6:1 under the conditions of (26±1)°C, relative humidity of (90±3)%, and photoperiod of 14L:10D for 24 to 48 hours, and then the bees are removed, and the parasitized eggs are placed in an environment with a temperature of (26±1)°C, relative humidity of (90±3)%, and photoperiod of 14L:10D for development to obtain offspring bees that have emerged from the parent host eggs; S3. Continuous breeding of trichogrammatid wasps: The offspring bees that have emerged from the parent host eggs in step (2) and the fresh mature ricinus silkworm eggs obtained in step (1) are used to continue breeding the bees. The bee breeding environment is: (26±1)℃, relative air humidity (75±3)%, and the photoperiod is 14L:10D. The bee breeding lasts for 24 to 48 hours, and then the bee species are removed. The offspring bees begin to develop in the development environment: (26±1)℃, relative air humidity (75±3)%.

2. The method for efficiently breeding Trichogramma separata using ricinus silkworm eggs according to claim 1, wherein The method for obtaining the fresh mature castor silkworm eggs described in S1 is to treat the newly emerged female castor silkworm moths at 45° C. for 2 hours, cut open the abdomen and wash with water to obtain the fresh mature castor silkworm eggs.

3. The method for efficiently breeding Trichogramma separata using ricinus silkworm eggs according to claim 1, wherein The method for obtaining the fresh mature castor silkworm eggs in S1 is to treat the newly emerged female castor silkworm moths at 4° C. for 3-7 days, cut open the abdomen and wash with water to obtain the fresh mature castor silkworm eggs.

4. The method for efficiently breeding Trichogramma separata using ricinus silkworm eggs according to claim 1, wherein The fresh mature ricinus silkworm eggs in control S1 were not completely dried and did not contain water droplets on the surface.

5. The method for efficiently breeding Trichogramma separata using ricinus silkworm eggs according to claim 1, wherein The surface moisture content of each fresh mature ricinus silkworm egg in S1 is controlled to be 5.26%-11.13%.

6. The method for efficiently breeding Trichogramma separata using ricinus silkworm eggs according to claim 1, wherein The method further includes S4, evaluating the quality of the offspring trichogrammatids bred from ricinus silkworm eggs, and using rice moth eggs to breed one generation for rejuvenation if the offspring do not meet the breeding expectations.

7. The method for efficiently breeding Trichogramma separata using ricinus silkworm eggs according to claim 6, wherein The bee species quality assessment includes assessing one or more of the following: parasitism rate, emergence rate, number of single-egg bees, and female-to-female ratio.

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