Method for expanding propagation of parasitic wasp cotesia chrysobrachiae of spodoptera frugiperda

Abstract

The invention provides a propagation method for parasitic wasp cotesia chrysobrachiae of spodoptera frugiperda, which comprises the following steps: collecting spodoptera frugiperda larvae parasitized by parasitic wasps in the field, and continuously feeding indoors; collecting parasitic wasp cocoons of the spodoptera frugiperda, and feeding until the wasp cocoons are subjected to eclosion; the adult bees after eclosion mate in an insect breeding cage, and after mating, spodoptera frugiperda or oriental armyworm larvae are provided as hosts, and potted corn seedlings are provided as host plants of host pests; after 24 h, parasitic host larvae are collected and continue to be bred till eclosion of the cocoons, and the parasitic wasp cotesia brasiliensis with the required number is obtained through the circulation in this way. In order to obtain a large amount of cotesia chrysobrachiae in one batch, the cotesia chrysobrachiae cocoons can be refrigerated and stored, and when parasitic wasps are to be used, the cotesia chrysobrachiae cocoons are placed at normal temperature to relieve diapause, so that the parasitic wasps are subjected to eclosion. The method is beneficial for improving the parasitism rate and offspring performance of cotesia chrysobrachidae, is suitable for large-scale indoor propagation of cotesia chrysobrachidae, and is beneficial for large-scale release of parasitic wasps in the field to prevent and control pests.

Description

Technical Field

[0001] The invention belongs to the technical field of propagation of a fall armyworm parasitic wasp, Cotesia fasciata, and particularly relates to a propagation method of a fall armyworm parasitic wasp, Cotesia fasciata. Background Art

[0002] The fall armyworm has many host plant species, strong reproductive capacity, long-distance migration and is difficult to control, causing great economic losses to corn production. At present, the control of fall armyworm is still mainly chemical control, but the long-term application of chemical pesticides is not only unfriendly to the environment, but has also caused the pest to develop varying degrees of resistance to most insecticides and Bacillus thuringiensis. Therefore, it is crucial to explore alternative sustainable control technologies, such as biological control methods, to effectively manage pests and reduce their impact on agricultural production. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for propagating the fall armyworm parasitic wasp, Cottonella fasciata, in view of the deficiencies in the above-mentioned prior art. The method is beneficial to improving the parasitism rate and offspring performance of Cottonella fasciata, is suitable for large-scale propagation of Cottonella fasciata indoors, and is beneficial to the large-scale release of the parasitic wasp in the field to control pests.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for propagating the fall armyworm parasitic wasp, Coleoptera:

[0005] S1. Collecting larvae of fall armyworm parasitized by parasitic wasps in the field and raising them indoors; the parasitic wasps are Coelophysis fasciatus;

[0006] S2. Collecting cocoons of parasitic bees of fall armyworm, raising them until the adults emerge, and obtaining the emerged adult bees;

[0007] S3. In an artificial climate box, the adult bees obtained in S2 are mated in an insect cage. After mating, 2-3 instar fall armyworm or 2-3 instar oriental armyworm larvae are provided as hosts to obtain parasitized host larvae, and potted corn seedlings are placed in the insect cage as host plants of the host; during the entire process from mating to parasitism, absorbent cotton soaked with 10% to 20% honey water is placed in a culture dish, and the culture dish is placed in the insect cage as supplementary nutrition for the adult bees;

[0008] S4, 24 hours later, collecting the parasitized host larvae obtained in S3, and continuing to raise them in the artificial climate box until the parasitic bee larvae drill out of the host larvae, form cocoons and eclode, and the ecloded adult bees obtained are cyclically repeated in steps S3-S4 to obtain the required number of parasitic bee Cottonella fasciata;

[0009] S5, collecting the parasitized host larvae, and continuing to raise them until the parasitic wasp larvae drill out of the host and spin cocoons to obtain bee cocoons;

[0010] S6. The bee cocoons obtained in S5 are stored in a cold environment at 4°C to 10°C, with a light cycle of L:D=0h:24h and a humidity of 65%. When the parasitic bees are to be used, the bee cocoons are released from diapause to allow the parasitic bees to emerge.

[0011] Preferably, the emerged adult bees in S3 are male and female adult bees within 2 days after emergence, and the mating time is 1 day to 2 days.

[0012] Preferably, the conditions of the artificial climate box in S3 and S4 are: a temperature of 25° C. to 27° C., a photoperiod of L:D=14h:10h, and a humidity of 70% to 85%.

[0013] Preferably, the bee cocoons in S5 are 1 to 3 day old bee cocoons.

[0014] Preferably, the conditions for releasing diapause in S6 are: in an artificial climate box with a temperature of 25°C to 27°C, a photoperiod of L:D=14h:10h, and a humidity of 70% to 85%.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The invention has low cost and simple operation, is beneficial to improving the parasitism rate and offspring performance of Cottonella taeniae, is suitable for mass propagation of Cottonella taeniae indoors, and is beneficial to mass release of the parasitic wasps in the field to control pests.

[0017] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Graph showing the parasitism rate of Cottonella serrata after different cold storage treatments in Example 1 of the present invention.

[0019] Figure 2 This is a graph showing the life span of female Coleoptera: Trichoderma after different cold storage treatments according to Example 1 of the present invention.

[0020] Figure 3 This is a graph showing the life span of the drone of the borer parasite after different cold storage treatments in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] Example 1

[0022] The method for propagating the fall armyworm parasitic wasp Coleoptera:

[0023] S1. Collecting larvae of fall armyworm parasitized by parasitic wasps in the field and raising them indoors; the parasitic wasps are Coelophysis fasciatus;

[0024] S2. Collecting cocoons of parasitic bees of fall armyworm, raising them until the adults emerge, and obtaining the emerged adult bees;

[0025] S3. In an artificial climate box, the adult bees obtained in S2 are mated in an insect cage. After mating for 1 to 2 days, 2 to 3 instar fall armyworms are provided as hosts to obtain parasitized host larvae, and potted corn seedlings are placed in the insect cage as host plants of the host; during the entire process from mating to parasitism, absorbent cotton soaked with 10% to 20% honey water is placed in a culture dish, and the culture dish is placed in the insect cage as supplementary nutrition for the adult bees; the adult bees after emergence are male and female adult bees within 2 days after emergence;

[0026] The host in this embodiment can also be a 2-3 instar larvae of the oriental armyworm as a host;

[0027] S4, 24 hours later, collecting the parasitized host larvae obtained in S3, and continuing to raise them in the artificial climate box until the parasitoid larvae drill out of the host larvae, form cocoons and eclode, and the ecloded adult bees obtained are cyclically repeated in steps S3-S4 to obtain the required number (100) of parasitic bee Cottonella fasciata;

[0028] The conditions of the artificial climate box in S3 and S4 are: a temperature of 25°C to 27°C, a photoperiod of L:D=14h:10h, and a humidity of 70% to 85%;

[0029] S5, collecting the parasitized host larvae, and continuing to raise them until the parasitoid larvae drill out of the host and spin cocoons, obtaining 1- to 3-day-old cocoons;

[0030] S6. To obtain a large number of Cottonella taeniae in a batch, the cocoons obtained in S5 are refrigerated and stored in an environment of 4°C to 10°C, a photoperiod of L:D=0h:24h, and a humidity of 65%. When the parasitic bees are to be used, the cocoons are released from diapause to allow the parasitic bees to emerge. The conditions for releasing diapause are as follows: the temperature is 25°C to 27°C, the photoperiod is L:D=14h:10h, and the humidity is 70% to 85%.

[0031] In order to further verify the beneficial effects of the present invention, the following comparative verification tests were also conducted in this embodiment:

[0032] 1. Effects of temperature on parasitism and offspring performance of Coleus sphaerocephalus

[0033] Experimental setup: The temperature was set at 20±1, 23±1, 26±1, 29±1 and 32±1°C (70±5%RH, L14:D10) for a total of 5 temperature treatments.

[0034] Twenty second-instar larvae of Spodoptera frugiperda were selected and placed in a plastic box (2000 mL) with a gauze mesh. Artificial feed was added for them to eat. A mated female bee was connected and a cotton ball dipped in 10% honey water was placed in it as supplementary nutrition for the parasitic bee. The plastic box was placed in an artificial climate chamber under the above-mentioned different temperature conditions. After 24 hours of parasitism, the box was dissected under a stereomicroscope, the number of parasitized Spodoptera frugiperda larvae was observed, and the parasitism rate was calculated.

[0035] A 2-year-old fall armyworm larva was placed in a test tube, and then a mated 2-day-old female Coleoptera sphaerocephala was introduced. After observing that the host was parasitized, the host was removed and placed in an artificial climate box at different temperatures and fed with corn leaves until the host cocooned. The number of cocoons produced by each host, the emergence rate, the female ratio, and the development period were counted. 20 male and female bees were collected and placed in an insect tank for feeding. Honey water was added as nutrition at 10 am and pm every day. The number of deaths was observed every day to calculate the lifespan of male and female bees.

[0036] Table 1 Effects of temperature on parasitism and offspring performance of Coleoptera: Coleoptera:

[0037]

[0038] Note: Different letters in the same column in the table indicate significant differences among different temperatures (P<0.05).

[0039] As shown in Table 1, the parasitism rate of the wasp was not affected by temperature at 20-32℃; the female ratio was highest at 23℃±1℃; the higher the temperature, the faster the development period; the lower the temperature, the longer the life span of the adult bee; the number of cocoons and the emergence rate were the highest at 26℃±1℃, indicating that 26℃ is close to or in the optimal temperature range for the growth and reproduction of the wasp, which can breed more parasitic offspring and is conducive to the expansion of the bee. 2. Effect of humidity on the parasitism and offspring performance of the wasp.

[0040] Experimental setup: Humidity was set to 4 humidity treatments: 40±5, 55±5, 70±5, 85±5% (26±1℃, L14:D10).

[0041] Twenty second-instar larvae of Spodoptera frugiperda were selected and placed in a plastic box (2000 mL) with a gauze mesh, artificial feed was added for them to eat, a mated female bee was connected, and a cotton ball dipped in 10% honey water was placed in it as supplementary nutrition for the parasitic bee. The plastic box was placed in the above-mentioned artificial climate chamber under different humidity levels. After 24 hours of parasitism, the box was dissected under a stereomicroscope, the number of parasitized Spodoptera frugiperda larvae was observed, and the parasitism rate was calculated.

[0042] A 2-year-old fall armyworm larva was placed in a test tube, and then a mated 2-day-old female Coleoptera ceratinae was introduced. After observing that the host was parasitized, the host was removed and placed in an artificial climate box with different humidity levels. The host was fed with corn leaves until cocoons were produced. The number of cocoons produced by each host, the emergence rate, the female-female ratio, and the development period were counted. 20 male and female bees were collected and placed in an insect tank for feeding. Honey water was added as nutrition at 10 am and pm every day. The number of deaths was observed every day to calculate the lifespan of male and female bees.

[0043] Table 2 Effects of humidity on parasitism and offspring performance of Coleoptera: Coleoptera:

[0044]

[0045] Note: Different letters in the same column in the table indicate significant differences among different temperatures (P<0.05).

[0046] As shown in Table 2, within the range of 40% to 85% humidity, the parasitism rate of the wasp had no significant difference; when the humidity was 70%, the number of cocoons and the emergence rate were the highest; when the humidity was 85%, the female ratio was the highest; when the humidity was 70% to 85%, the life span of the adult bees was longer. Therefore, choosing a humidity of 70% to 85% is conducive to the expansion of the bee. Under this condition, the parasitic bee has a large number of offspring, a high female ratio, and a long life span.

[0047] 3. Effects of photoperiod on parasitism and offspring performance of Coleus sphaerocephalus

[0048] Experimental setup: The photoperiod was set to L16:D8, L14:D10, L12:D12, L10:D14, L8:D16 (26±1°C, 85±5% RH) for a total of 5 photoperiod treatments.

[0049] Twenty second-instar larvae of Spodoptera frugiperda were selected and placed in a plastic box (2000 mL) with a gauze mesh. Artificial feed was added for them to eat. A mated female bee was connected and a cotton ball dipped in 10% honey water was placed in it as supplementary nutrition for the parasitic bee. The plastic box was placed in the artificial climate chamber under the above-mentioned different light cycles. After 24 hours of parasitism, the box was dissected under a stereomicroscope, the number of parasitized Spodoptera frugiperda larvae was observed, and the parasitism rate was calculated.

[0050] A 2-year-old fall armyworm larva was placed in a test tube, and then a mated 2-day-old female Coleoptera sphaerocephala was introduced. After observing that the host was parasitized, the host was removed and then placed in an artificial climate box under different photoperiods and fed with corn leaves until the host cocooned. The number of cocoons produced by each host, the emergence rate, the female ratio, and the development period were counted. 20 male and female bees were collected and placed in an insect tank for feeding. Honey water was added at 10 am and pm every day as a supplementary nutrition. The number of deaths was observed every day to calculate the lifespan of male and female bees.

[0051] Table 3 Effects of photoperiod on parasitism and offspring performance of Coleoptera: Coleoptera:

[0052]

[0053] Note: Different letters in the same column in the table indicate significant differences among different temperatures (P<0.05).

[0054] As shown in Table 3, under the photoperiod of L14:D10, the parasitism rate, emergence rate, and female ratio of the wasp were the highest, and the female wasp lifespan was the longest; when the photoperiod was L10:D14, the number of cocoons was the highest; the longer the light, the faster the parasitic wasp developed. Overall, the photoperiod L14:D10 is a better condition for expansion and propagation. Under this condition, the parasitism rate of the parasitic wasp is much higher than that of other photoperiods, which means that under this condition, the parasitic wasp can reproduce more offspring in the same time.

[0055] 4. Cold storage conditions of Cottonella oleracea

[0056] Experimental settings: (1) Storage temperature: 4, 7, 10℃ (65±5% RH, photoperiod L0:D24), controlled by an artificial climate chamber; (2) Storage age: 1-day-old, 2-day-old, 3-day-old cocoons; (3) Storage time: 7, 14, 21, 28, 35 days. Unrefrigerated cocoons of the wasp were used as controls.

[0057] 100 1-day-old, 2-day-old or 3-day-old cocoons of the full-bodied Corythuja serrata were selected and placed in centrifuge tubes (1.5 mL) respectively, with one cocoon in each tube, and placed in an artificial climate box with corresponding settings. After reaching the set storage time, they were taken out and placed in an artificial climate box with 26°C ± 1°C, 70%-85% RH, and L14:D10. The emergence of the cocoons of the Corythuja serrata wasp was counted daily until no more emergence occurred, the emergence number was recorded, and the emergence rate was calculated. The experiment was repeated 5 times. The results are shown in Table 4.

[0058] Table 4 The emergence rate of cocoons of Acanthidae serrata after low temperature storage

[0059]

[0060] Note: Data are mean ± standard error. Different lowercase letters indicate significant differences between treatments with different storage times under the same temperature and age; different uppercase letters indicate significant differences between treatments with different storage temperatures under the same time and age. E indicates that the ceratosporinus has emerged during this low temperature treatment; - indicates that the ceratosporinus has not emerged after this low temperature treatment.

[0061] In order to screen out the best low-temperature storage conditions, the above treatments with an emergence rate greater than 50% were selected for further biological research. The newly emerged adult bees in each of the above treatments were paired at a ratio of drones: female bees = 1:1, and after pairing, they were placed in an artificial climate box at 26℃±1℃, 70%~85%RH, L14:D10 for mating for 24 hours, and cotton balls dipped in 10% honey water were used to provide nutrition. 20 second-instar larvae of fall armyworm were placed in a plastic box with gauze (2000mL), and artificial feed was placed in it, and one of the mated female bees was introduced for parasitism. After 24 hours, they were taken out, and all fall armyworm larvae were dissected under a stereo microscope, the number of parasitized fall armyworms was counted, and the parasitism rate was calculated. The experiment was repeated 10 times.

[0062] The control group (CK) consisted of cocoons that were not refrigerated but directly placed in an artificial climate box at 26°C ± 1°C, 70% to 85% RH, L14:D10. After they emerged, they were treated in the same way as the treatment group.

[0063] Depend on Figure 1 It can be seen that the parasitism rate of parasitoids was the highest when the one-day-old cocoons were stored at 7℃ for 7 days and then released from diapause, which was not significantly different from that of the control group; the parasitism rate of parasitoids was the highest when the two-day-old cocoons were stored at 10℃ for 14 days and then released from diapause, which was not significantly different from that of the control group; there was no significant difference between the parasitoids and the control group when the three-day-old cocoons were stored at 7℃ for 7 or 14 days, and at 10℃ for 7 days and then released from diapause.

[0064] Randomly select 8 newly emerged female bees and 8 drones, put them into a homemade insect jar (diameter = 5.5 cm, height = 6.5 cm), put cotton balls soaked in 10% honey water in advance in the jar to provide nutrition, and put them into an artificial climate box at 26℃±1℃, 70%~85%RH, L14:D10 for breeding. Observe and count the survival of all adult bees every 24 hours. Supplement 10% honey water every day until the adult bees die. Repeat the experiment 5 times.

[0065] The control group (CK) consisted of cocoons that were not refrigerated but placed directly in an artificial climate box at 26°C ± 1°C, 70% to 85% RH, L14:D10. After they emerged, the survival statistics were performed in the same way as the treatment group.

[0066] Depend on Figure 2 It can be seen that when one-day-old cocoons are stored at 7 or 10℃ for 7 days, the lifespan of female bees is higher, second only to the control; when two-day-old cocoons are stored at 4 or 7℃ for 7 days, and at 10℃ for 7 days or 14 days, there is no significant difference in the lifespan of female bees, both of which are second only to the control group; the lifespan of female bees is not affected by the storage of 3-day-old cocoons under various treatments, and there is no significant difference.

[0067] Depend on Figure 3It can be seen that when one-day-old cocoons are stored at 7 or 10℃ for 7 days, the lifespan of male bees is higher, second only to the control; when two-day-old cocoons are stored at 7℃ for 7 days, and at 10℃ for 7 days or 14 days, there is no significant difference in the lifespan of male bees, both of which are second only to the lifespan of the control group; when three-day-old cocoons are stored at 4, 7, and 10℃ for 7 days, and at 7℃ for 14 days, there is no significant difference in the lifespan of female bees, both of which are second only to the lifespan of the control group.

[0068] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for propagating the parasitic wasp Coleoptera: ... The method is: S1. Collecting larvae of fall armyworm parasitized by parasitic wasps in the field and raising them indoors; the parasitic wasps are Coelophysis fasciatus; S2. Collecting cocoons of parasitic bees of fall armyworm, raising them until the adults emerge, and obtaining the emerged adult bees; S3, in an artificial climate box, mating the emerged adult bees obtained in S2 in an insect cage, providing 2-3 instar fall armyworm or 2-3 instar oriental armyworm larvae as hosts to obtain parasitized host larvae, and placing potted corn seedlings as host plants of the hosts in the insect cage; During the whole process from mating to parasitism, a cotton ball soaked with 10% to 20% honey water is placed in a culture dish, and the culture dish is placed in the insect cage as supplementary nutrition for the adult bees; S4, 24 hours later, collect the parasitized host larvae obtained in S3, continue to raise them in the artificial climate box until the parasitoid larvae drill out of the host larvae and form cocoons, and the cocoons are ecloded, and the ecloded adult bees are obtained, and the operations of steps S3-S4 are repeated in a cycle to obtain the required number of parasitic bees; S5, collecting the parasitized host larvae, and continuing to raise them until the parasitic wasp larvae drill out of the host and spin cocoons to obtain bee cocoons; S6. The bee cocoons obtained in S5 are stored in a cold environment at 4°C to 10°C, with a light cycle of L:D=0h:24h and a humidity of 65%. When the parasitic bees are to be used, the bee cocoons are released from diapause to allow the parasitic bees to emerge.

2. A method for propagating the fall armyworm parasitic wasp Coleoptera: ... The emerged adult bees described in S3 are male and female adult bees within 2 days after emergence, and the mating time is 1 day to 2 days.

3. A method for propagating the fall armyworm parasitic wasp Coleoptera: ... The conditions of the artificial climate box in S3 and S4 are: a temperature of 25° C. to 27° C., a photoperiod of L:D=14h:10h, and a humidity of 70% to 85%.

4. A method for propagating the fall armyworm parasitic wasp Coleoptera: ... The cocoons described in S5 are 1 to 3 days old cocoons.

5. A method for propagating the fall armyworm parasitic wasp Coleoptera: ... The conditions for releasing diapause in S6 are: in an artificial climate chamber with a temperature of 25°C to 27°C, a photoperiod of L:D=14h:10h, and a humidity of 70% to 85%.

Images