A method for improving egg production of beet armyworm by 60Co-gamma ray irradiation

Abstract

This invention belongs to the field of agricultural and forestry biotechnology, and relates to a method utilizing... 60 A method to increase the oviposition rate of beet armyworm by Co-γ irradiation was used. Beet armyworm pupae within 12 hours of pupal instar were collected and subjected to effective accumulated temperature treatment. Then, for male beet armyworm pupae, [further methods were employed]. 60 Co-source irradiation treatment; irradiated male beet armyworm pupae and unirradiated female pupae were placed in an incubator to cultivate and emerge as adults. The adults were then transferred to adult rearing cages and supplemented with honey water for nutrition. This invention, through effective accumulated temperature treatment, selects a large number of uniformly developed male beet armyworm pupae as irradiation targets. While ensuring emergence rate and adult lifespan, it significantly increases the egg production of beet armyworms and the yield of test insects. The operation process is simple, safe, and reliable. It provides a large source of production insects for the convenient and rapid use of beet armyworms to produce the biological control agent nucleopolyhedrovirus, and for using the insect as a host to propagate natural enemy parasitic wasps.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of bio-technology in agriculture and forestry, and relates to a method for improving the egg production of Spodoptera exigua by using gamma rays. 60 The present application belongs to the field of bio-technology in agriculture and forestry, and relates to a method for improving the egg production of Spodoptera exigua by using gamma rays. BACKGROUND

[0002] Spodoptera exigua Hübner, also known as green bagworm, corn leaf moth, belongs to Lepidoptera, Noctuidae, Spodoptera, and is also an important agricultural pest, which can harm more than 170 kinds of vegetables and crops such as cabbage, cauliflower, Chinese cabbage, radish, lettuce, green onion, tomato, and green pepper. At the same time, Spodoptera exigua is also used as a production material of insect nucleopolyhedrovirus or a host insect for rearing natural enemies, so it is very important to provide a large number of insects with consistent development and physiological characteristics under indoor conditions all year round.

[0003] At present, there are many reports on the indoor breeding technology of Spodoptera exigua at home and abroad, which generally configures artificial feed according to different grain feed formulas and according to the feeding method of Noctuidae insects. However, most of the existing breeding technology researches are focused on feeding devices and feed, which can improve the survival rate of adult insects. After searching, no relevant reports on improving the egg production of female adult Spodoptera exigua, especially using Co-γ rays, have been found. 60 SUMMARY

[0004] The present application aims to provide a method for improving the egg production of Spodoptera exigua by using Co-γ rays. 60 The present application aims to provide a method for improving the egg production of Spodoptera exigua by using Co-γ rays. 60 Co-γ rays, and then pairing the hatched female and male adult insects for feeding, which can greatly improve the egg production of Spodoptera exigua under the premise of ensuring the pupa hatching rate and adult insect life span, and improve the production of test insects. The operation process is simple, safe and reliable, which provides a large number of production insect sources for conveniently and quickly producing biological control agent nucleopolyhedrovirus by using Spodoptera exigua, and expanding the natural enemy parasitic wasps by using the insect as a host.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] A method for improving the egg production of Spodoptera exigua by using Co-γ rays, comprising the following steps: 60 Co-γ rays, and then pairing the hatched female and male adult insects for feeding, which can greatly improve the egg production of Spodoptera exigua under the premise of ensuring the pupa hatching rate and adult insect life span, and improve the production of test insects. The operation process is simple, safe and reliable, which provides a large number of production insect sources for conveniently and quickly producing biological control agent nucleopolyhedrovirus by using Spodoptera exigua, and expanding the natural enemy parasitic wasps by using the insect as a host.

[0007] Step S1: fixed effective accumulated temperature culture treatment ​

[0008] Step S11: Collecting the pupae of Spodoptera exigua of 12 hours old from the field collected population or the indoor artificially bred population, placing them in a kraft paper bag, and sealing the bag opening;

[0009] Step S12: Placing the kraft paper bag in an incubator with constant temperature of 26-28℃ and light for 8-12 hours, and culturing for 5-6 days, i.e. the effective accumulated temperature of the pupae reaches 48.5-70.2 day-degree (5 days x (26 degrees-16.3 degrees) to 6 days x (28 degrees-16.3 degrees)), and waiting for receiving irradiation;

[0010] Step S2: Irradiation treatment

[0011] Step S21: Selecting the male pupae of Spodoptera exigua treated by the effective accumulated temperature, placing them in a kraft paper bag, and irradiating them by a Co source, with an irradiation dose of 50 Gy; 60 Co source for irradiation, with an irradiation dose of 50 Gy;

[0012] Step S22: Irradiation 60 The intensity requirement of the Co source: the Co source is stored at a depth of 6-10 m underwater, and the irradiation dose rate is 0.5-4 Gy / min;

[0013] Step S3: Pupa culture and adult feeding

[0014] Step S31: Mixing the irradiated male pupae of Spodoptera exigua with the female pupae of Spodoptera exigua treated by the effective accumulated temperature but not irradiated, at a ratio of 1:1, and placing them in a kraft paper bag, and placing them in an incubator with constant temperature of 26-28℃ and light for 8-12 hours for culture;

[0015] Step S32: After the pupae are hatched into adults, the adults are moved to the adult feeding cage with nylon net, and the oviposition carrier medium is hung in the cage for attracting the adults to lay eggs, and honey water is supplemented as the supplement of the adults;

[0016] Step S33: Replacing the oviposition carrier medium every morning, and washing the egg mass with water, and placing it at room temperature, and after the eggs are hatched into larvae, using plant host leaves or artificial feed for subsequent feeding in the room.

[0017] Further, in the steps S12 and S31, the incubator is an artificial climate box or a plant and animal culture box with temperature, humidity and light control.

[0018] Further, in the step S12, the incubator is set to constant temperature of 26-28℃, which means that a certain constant temperature is set between 26 and 28℃; and the incubator is set to light for 8-12 hours, which means that the light time is set to be between 8 and 12 hours in one day (24 hours).

[0019] Further, in the step S21, a dosimeter is arranged in the irradiation process to ensure accuracy. The dosimeter is arranged with 30-40 dosimeters with an error of ±0.1 Gy.

[0020] Further, the egg-laying carrier medium is kraft paper or sulfuric acid paper.

[0021] Further, in the step S32, the concentration of the honey water is 10-20%.

[0022] Further, in the step S32, in the adult rearing cage, the adult density volume is 15-30 cm 3 / head.

[0023] Further, in the step S33, the water is physiological saline or pure water. Preferably, the physiological saline is a sodium chloride solution with a concentration of 0.9%.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The present application selects a large number of 5-6 day old pupae of the beet armyworm with consistent development as irradiation objects by controlling temperature and light, which can greatly promote the egg-laying amount of the beet armyworm and improve the production of test insects under the premise of ensuring the pupal emergence rate and adult longevity of the beet armyworm. The operation process is simple, safe and reliable, which provides a large amount of production insect source for conveniently and quickly producing biological control agent nuclear polyhedrosis virus by using the beet armyworm and expanding the host beet armyworm to breed natural enemies.

[0026] 2. Using pupae as a relatively fixed and inactive treatment insect state can ensure the average irradiation penetration effect of each test insect by γ-rays during treatment, stimulate the growth response of the insect body, and the early test insect treatment is simple and has few constraints, which is conducive to standardization of operation.

[0027] 3. Using 60 Co as an insect treatment irradiation source for low-dose irradiation can promote the growth of the beet armyworm, improve the egg-laying amount, achieve the purpose of promoting the increase and production of the beet armyworm, and is conducive to factory production and implementation of test insects. DETAILED DESCRIPTION

[0028] The specific embodiments of the present application will be further described in detail below with reference to the examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application. In the following examples, the experimental methods are conventional methods unless otherwise specified. In the following examples, the materials, reagents, etc. are commercially available unless otherwise specified, and analytical grade reagents are preferred.

[0029] Example 1

[0030] 1. Constant temperature treatment of Spodoptera exigua pupae to make the developmental effective accumulated temperature consistent

[0031] Spodoptera exigua pupae that had pupated within 12 h were selected from the indoor population, and after identification of females and males, 80 Spodoptera exigua pupae (40 females and 40 males) were selected at a female to male ratio of 1:1, placed in a cowpaper bag, and the bag opening was sealed. The bag was placed in an artificial climate chamber at a constant temperature of 27°C and under illumination for 10 h, and after 5 days, the bag was taken out and irradiated.

[0032] 2. 60 Irradiation treatment of Spodoptera exigua pupae with a Co source

[0033] The 5-day-old Spodoptera exigua male pupae that had been treated at a constant temperature were placed in a cowpaper bag and sent to the Hainan Haikou Zhonghe Haoyuan Irradiation Factory for irradiation treatment. Irradiation was performed using a Co source at a depth of 8 m under water, and the irradiation dose was 50 Gy, the dose rate was set to 3 Gy / min, and 30-40 dosimeters with an error of ±0.1 Gy were provided to ensure accuracy.

[0034] 3. Treatment and subculture rearing of irradiated pupae and adults and biological observation

[0035] After the irradiated Spodoptera exigua male pupae were brought back to the laboratory, female Spodoptera exigua pupae that had been treated at a constant temperature but not irradiated were selected, mixed at a female to male ratio of 1:1, and placed in an artificial climate chamber to be cultured until eclosion, and the eclosion was recorded. 10 pairs of female and male adults were placed in a 30x30x30 cm rearing cage, and cotton balls containing 15% honey water were provided as supplementary nutrition, and the survival life of female and male adults was recorded every day. After 2 days, a piece of cowpaper with a size of about 15x15 cm was hung in the center of the top of the cage as an oviposition carrier medium to induce oviposition. The cowpaper was replaced every morning, and the oviposition was checked and the paper containing the oviposition was cut along the outer edge of the oviposition 1 cm away, the oviposition was washed with a syringe containing physiological saline to remove possible pathogens, and after drying, the oviposition was stored and the oviposition and oviposition hatching were recorded after the larvae hatched. This treatment was repeated 3 times.

[0036] Example Two

[0037] 1. Constant temperature treatment of Spodoptera exigua pupae to make the developmental effective accumulated temperature consistent

[0038] Spodoptera exigua pupae that had pupated within 12 h were selected from the indoor population, and after identification of females and males, 80 Spodoptera exigua pupae (40 females and 40 males) were selected at a female to male ratio of 1:1, placed in a cowpaper bag, and the bag opening was sealed. The bag was placed in an artificial climate chamber at a constant temperature of 28°C and under illumination for 8 h, and after 6 days, the bag was taken out and irradiated.

[0039] 2. 60 Irradiation treatment of Spodoptera exigua pupae with a Co source

[0040] The 6-day-old beet armyworm pupae treated by constant temperature were put into the cowhide paper bag, and sent to the Haikou City, Hainan Province, China Nuclear Haoyuan Irradiation Factory for irradiation treatment. The Co source was pulled out underwater to 6.5 m deep for post-irradiation, the irradiation dose was 50 Gy, the dose rate was set to 2 Gy / min, and 30-40 dose meters with an error of ±0.1 Gy were provided to ensure accuracy.

[0041] 3. Pupa, adult treatment and subculture feeding and biological observation after irradiation

[0042] After the irradiated beet armyworm pupae were brought back to the laboratory, the female beet armyworm pupae treated by constant temperature but not irradiated were selected, mixed at a ratio of 1:1, and placed in an artificial climate chamber for cultivation until eclosion. The eclosion was recorded. 10 pairs of male and female adults were put into a 30x30x30cm insect cage, and cotton balls containing 10% honey water were provided as supplementary nutrition. The survival life of male and female adults was recorded every day. After 2 days, a piece of about 15x15cm sulfuric acid paper was hung in the center of the cage as an egg laying medium for beet armyworms to induce oviposition. The sulfuric acid paper was replaced every morning, and the egg blocks were cut out along the 1cm edge of the paper, washed with physiological saline, dried, and stored. After the larvae were hatched, the oviposition and egg hatching were recorded. This treatment was repeated 3 times.

[0043] Example Three

[0044] 1. Constant temperature treatment of beet armyworm pupae to make the effective accumulated temperature consistent

[0045] Beet armyworm pupae that had pupated within 12 hours were selected from the indoor population. After identification of female and male, 80 beet armyworm pupae (40 female and 40 male) were selected at a ratio of 1:1 and placed in a cowhide paper bag with the bag opening sealed. They were placed in an artificial climate chamber with constant temperature of 26°C and light for 12 hours. After 6 days, they were taken out for irradiation.

[0046] 2. 60 Irradiation treatment of beet armyworm pupae with Co source

[0047] The 6-day-old beet armyworm pupae treated by constant temperature were put into the cowhide paper bag, and sent to the Haikou City, Hainan Province, China Nuclear Haoyuan Irradiation Factory for irradiation treatment. The Co source was pulled out underwater to 6.5 m deep for post-irradiation, the irradiation dose was 50 Gy, the dose rate was set to 2 Gy / min, and 30-40 dose meters with an error of ±0.1 Gy were provided to ensure accuracy.

[0048] 3. Pupa, adult treatment and subculture feeding and biological observation after irradiation

[0049] After the irradiated Spodoptera exigua pupae were brought back to the laboratory, female pupae that had been treated at constant temperature but not irradiated were selected, mixed at a ratio of 1:1, and placed in an artificial climate chamber to cultivate until eclosion. Ten pairs of male and female adults were placed in a 30x30x30 cm insect cage, and cotton balls containing 20% honey water were provided as supplementary nutrition. The survival life of male and female adults was recorded every day. Two days later, a piece of about 15x15 cm cowhide paper was hung in the center of the cage as an oviposition carrier medium to attract oviposition. The cowhide paper was replaced every morning, and the oviposition was checked and cut out from the paper 1 cm from the edge of the oviposition mass. The oviposition mass was washed with a syringe containing physiological saline to remove possible pathogens, and then dried and stored. After the larvae were hatched, the oviposition and hatching were recorded. This treatment was repeated three times.

[0050] Comparative test:

[0051] The process was the same as in Example 1, and the irradiation dose of the Spodoptera exigua pupae was adjusted. Control 1: 10 Gy irradiation of male pupae + 10 Gy irradiation of female pupae; control 2: 100 Gy irradiation of male pupae + non-irradiated female pupae; control 3: 300 Gy irradiation of male pupae + non-irradiated female pupae; control 4: non-irradiated male pupae + non-irradiated female pupae. The eclosion, adult survival life, oviposition amount, and hatching were recorded.

[0052] Pupa eclosion rate = (number of eclosed pupae / total number of pupae) x 100%

[0053] Oviposition rate = (number of hatched larvae / number of observed oviposition masses) x 100%

[0054] Single female oviposition amount = total oviposition amount / number of ovipositing females

[0055] According to the recorded data, the eclosion rate, adult life span, single female oviposition amount, and hatching rate were calculated, and the results are shown in Tables 1, 2, and 3.

[0056] Table 1 Eclosion of Spodoptera exigua pupae after irradiation at different doses

[0057] Item Dose S. exigua females S. exigua males Example I 50 Gy 90.0％±5.8％a 100.0％a Example II 50 Gy 87.2％±6.2％a 100.0％a Example III 50 Gy 88.6％±3.9％a 100.0％a Control I 10 Gy 81.7％±4.4％a 100.0％a Control II 100 Gy 89.0％±1.2％a 100.0％a Control III 300 Gy 85.7％±3.1％a 90.0％±5.8％a Control IV 0 Gy 86.7％±3.3％a 100.0％a

[0058] As can be seen from Table 1, the use of a 50 Gy dose 60 The eclosion rate of the Spodoptera exigua pupae irradiated with a Co source was 100%, which was not significantly different from the eclosion rates of the other dose control groups (10 Gy, 100 Gy, 300 Gy, and 0 Gy), which were between 90% and 100%. The eclosion rate of the Spodoptera exigua pupae irradiated with 10 Gy (control 1) was 81.7%, which was slightly lower than that of the example (non-irradiated) and the other control groups (non-irradiated). This indicates that irradiation of Spodoptera exigua pupae with 10 Gy has a certain effect on the eclosion rate.

[0059] Table 2 Life span of adult of Heliothis armigera irradiated by different doses

[0060] Item Dose S. exigua females S. exigua males Example I 50 Gy 11.0±1.7a 12.3±0.3a Example II 50 Gy 11.7±3.4a 11.8±1.5a Example III 50 Gy 10.2±0.6a 12.0±0.8a Control I 10 Gy 8.5±2.0a 9.5 ± 1.3 ab Control II 100 Gy 10.4±1.0a 9.5 ± 1.7 ab Control III 300 Gy 10.0±1.0a 10.0 ± 0.5 ab Control IV 0 Gy 10.0±0.7a 6.5±0.3b

[0061] As shown in Table 2, the life span of male adult of Heliothis armigera irradiated by different doses of male pupae varies greatly, in which the life span of male adult of Heliothis armigera irradiated by 50 Gy is the highest, which is 12.3 days, significantly higher than that of the control four (non-irradiated) male adult (6.5 days). The life span of female adult of Heliothis armigera irradiated by 10 Gy (control one) is 8.5 days, lower than that of the example (non-irradiated) and other control groups (non-irradiated). It is shown that the present application can effectively improve the life span of male adult of Heliothis armigera, but irradiation of female pupae of Heliothis armigera has a certain influence on the life span of female adult.

[0062] Table 3 Oviposition and hatching rate of Heliothis armigera irradiated by different doses

[0063]

[0064] As shown in Table 3, the oviposition and hatching rate of Heliothis armigera irradiated by 50 Gy of male pupae are significantly improved, which are 893.5 and 90.86% respectively, higher than those of the control four (non-irradiated) and other doses of irradiation. It is shown that the present application can effectively improve the oviposition and hatching rate of Heliothis armigera irradiated by 50 Gy of male pupae, and obtain the effect of beneficial population breeding in artificial breeding and propagation of Heliothis armigera.

[0065] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, some improvements and refinements can be made without departing from the technical principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method of utilizing 60 A method for increasing the egg-laying rate of the beet armyworm by Co-γ ray irradiation, characterized in that... Includes the following steps: Step S1: Fixed effective accumulated temperature incubation treatment Step S11: Collect beet armyworm pupae within 12 hours of pupal instar from wild-collected populations or indoor artificially reared populations, place them in kraft paper bags, and seal the bag opening. Step S12: Place the kraft paper bag in an incubator with a constant temperature of 26-28℃ and a light exposure of 8-12 hours for 5-6 days, until the effective accumulated temperature of the pupae reaches 48.5-70.2 h·°C, ready for irradiation; the constant temperature of 26-28℃ in the incubator means setting a constant temperature between 26 and 28℃; the light exposure time of 8-12 hours in the incubator means setting the light exposure time between 8 and 12 hours per day. Step S2: Irradiation treatment Step S21: Select male beet armyworm pupae that have undergone effective accumulated temperature treatment, place them in a kraft paper bag, and use... 60 Irradiation was performed using a Co source at a dose of 50 Gy. Step S22: Irradiation 60 The intensity requirements for the Co source are as follows: the Co source is stored at a depth of 6 to 10 m underwater, and the irradiation dose rate is 0.5 to 4 Gy / min. Step S3: Pupae culture and adult rearing Step S31: Mix the irradiated male beet armyworm pupae with the beet armyworm female pupae that have undergone effective accumulated temperature treatment but have not been irradiated at a female-to-male ratio of 1:1, then place them in a kraft paper bag and incubate them in an incubator with a constant temperature of 26-28℃ and light for 8-12 hours. Step S32: After the pupae emerge as adults, the adults are transferred to nylon mesh rearing cages. An egg-laying medium is suspended in the cages, and honey water is added as supplementary nutrition for the adults. The adult rearing cages maintain a density of 15–30 cm³ of adult insects per cubic centimeter. 3 / head; the concentration of the honey water is 10-20%; Step S33: Change the oviposition medium every morning, rinse the egg mass with physiological saline, place it at room temperature, and after the eggs hatch into larvae, continue to raise them indoors using plant host leaves or artificial feed; the physiological saline is a 0.9% sodium chloride solution.

2. The method according to claim 1, characterized in that: In steps S12 and S31, the incubator is an artificial climate chamber or a plant and animal incubator with temperature, humidity and light control.

3. The method according to claim 1, characterized in that: In step S21, a dosimeter is used during the irradiation process.

4. The method according to claim 3, characterized in that: The dosimeter is equipped with 30 to 40 dosimeters with an error of ±0.1 Gy.

5. The method according to claim 1, characterized in that: In step S32, the oviposition carrier medium is kraft paper or sulfuric acid paper.

Images