Method for researching parasitic ability of noctuid black egg bees to prodenia litura

Abstract

The invention discloses a method for researching the parasitic ability of noctuid black egg bees to prodenia litura, and relates to the technical field of agricultural biological control, and the method comprises the following steps: S1, insect feeding: feeding and breeding noctuid black egg bees and prodenia litura for test; s2, testing parasitic function reactions of the noctuid black egg bees to the prodenia litura with different egg densities, namely respectively inoculating a plurality of groups of fresh prodenia litura eggs with different densities into a glass finger-shaped tube, introducing a female bee of the noctuid black egg bees which are mated within 12 hours after eclosion, dispensing honey water into the tube wall of the finger-shaped tube for the female bee to eat, and sealing with black cloth and a rubber band; and culturing in an artificial climate box. The effect of the invention can be popularized and applied to prevention and control of noctuid pests by the black ovum noctuid, the use amount of chemical pesticides can be effectively reduced, the pesticide residue and plant protection cost of tomatoes are reduced, and the safety of the tomatoes is improved.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural biological control, in particular to a method for studying the parasitic ability of Spodoptera litura black egg wasp on Spodoptera litura. Background Art

[0002] Agriculture is the primary industry, and food security in the new era is a necessary guarantee for promoting agricultural development. Soybean is an important agricultural crop in my country and one of the main cash crops in my country. It occupies an important position in my country's agricultural production. For a long time, the prevention and control of agricultural pests has mainly relied on the repeated application of chemical pesticides in large quantities. The irrational use of chemical pesticides leads to the rapid development of pest resistance in pests and the serious occurrence of secondary pests, which destroys the ecological balance in the field and increases the difficulty of pest control. To this end, the Guizhou Provincial Government issued the "Action Plan for the Integrated Development of Green Prevention and Control and Integrated Prevention and Control of Characteristic Advantageous Crops in Guizhou Province (2019-2020)" to accelerate the integrated development of green prevention and control and integrated prevention and control of pests and diseases of characteristic advantage crops. The application of natural enemies can slow down the development of resistance in vegetable pests. The development of green prevention and control technology based on the use of natural enemies is an important means to achieve zero growth of chemical pesticides in Guizhou and green prevention and control of vegetable pests throughout the process.

[0003] Spodoptera litura (Fabricius), belonging to the order Lepidoptera, family Noctuidae, is a worldwide agricultural pest, distributed in all major vegetable producing areas in my country. Spodoptera litura has strong concealment, omnivorousness, gluttony, explosiveness and strong reproductive capacity, and the main damage is caused by larvae. Young larvae feed on the middle and lower leaves of the plant, and gradually move to the upper leaves as they age, seriously affecting the quality and yield of vegetable production in our province. At present, chemical control is still the main means of control for Spodoptera litura, but the long-term use of chemical pesticides has significantly enhanced the resistance of Spodoptera litura, reduced the biodiversity of vegetable fields, polluted the environment, and increased the amount of pesticide residues in vegetables, ultimately affecting the quality and yield of vegetables.

[0004] Biological control mainly uses parasitic natural enemies, pathogenic microorganisms and predatory natural enemy insects. Parasitic natural enemies are important biological control resources for Spodoptera litura. There are 40 reported parasitic natural enemies of Spodoptera litura, including Micropliti sprodeniae, Meteorus pulchricornis, Metopius rufus and Telenomus remus. Field trials found that the average parasitism rate of Micropliti sprodeniae was 22.31%, which has a good control effect on pest populations. The parasitism rate of Telenomus remus on eggs of Spodoptera litura can reach more than 95%. Telenomus remus belongs to the family of Hymenoptera. According to reports, many studies at home and abroad have proved that the noctuid black egg wasp has a high parasitic ability on the eggs of Lepidoptera Noctuidae insects such as fall armyworm (S. frugiperda), fall armyworm (S. litura), tobacco budworm (Helicoverpa assulta (Guenée, 1852)), cotton bollworm (Helicoverpa armigera). Noctuid black egg wasp has a good application prospect because of its short generation period (average 10 days), life span of up to 20 days, strong field adaptability, high egg parasitism rate, fast propagation speed, and wide temperature and humidity adaptability.

[0005] Therefore, a research method for the parasitic ability of the black egg wasp of the noctuid armyworm to the cutworm is proposed, aiming to provide a reference for the large-scale promotion and application of the black egg wasp of the noctuid armyworm to control noctuid pests in the future, reduce the use of chemical pesticides, reduce tomato pesticide residues and plant protection costs, and increase tomato safety. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings in the prior art and to propose a method for studying the parasitic ability of the black egg wasp of the noctuid armyworm to the cutworm.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: The method for studying the parasitic ability of the noctuid black egg wasp to the cutworm includes the following steps: S1. Insect breeding: raising and breeding black egg wasps and Spodoptera litura for use in experiments; S2. Experimental parasitic functional response of the black egg wasp to different egg densities of Spodoptera litura: multiple groups of fresh eggs of Spodoptera litura with different densities were placed in glass finger-shaped tubes, and a female bee of the black egg wasp that had mated within 12 hours of emergence was introduced. Honey water was applied to the wall of the finger-shaped tube for the female bee to feed on, and the tube was sealed with black cloth and rubber bands; it was placed in an artificial climate chamber for cultivation; after 24 hours, the female bee was removed, and the eggs of Spodoptera litura continued to be cultured under the same conditions. If any unparasitized eggs hatched during the culture process, the newly hatched larvae were removed in time to avoid them from feeding on the parasitized eggs; after 5 days of parasitism, the number of parasitized eggs was observed under a stereo microscope. If the eggs turned black, it meant that the eggs were parasitized by the black egg wasp, and the parasitism rate was calculated; after the offspring bees emerged, they were waited for their death, and the number of emerging and female bees was counted, and the emergence rate and female ratio were calculated. Each group of treatments was repeated 10 times, and the calculation formula was: ; ; ; S3. Experiment on the interference effect of the density of the black egg wasp: Into glass finger-shaped tubes containing 60 fresh eggs of Spodoptera litura, different numbers of female bees of the black egg wasp of Spodoptera litura that had mated within 12 hours of emergence were introduced, and honey water was applied to the wall of the finger-shaped tubes for the female bees to feed on, and the tubes were sealed with black cloth and rubber bands; they were cultured in an artificial climate box; after 24 hours, the female bees were removed, and the eggs of Spodoptera litura continued to be cultured under the same conditions. If any unparasitized eggs hatched during the culture process, the newly hatched larvae were removed in time to avoid them from feeding on the parasitized eggs; after 5 days of parasitism, the number of parasitized eggs was observed under a stereo microscope. If the eggs turned black, it meant that the eggs were parasitized by the black egg wasp of Spodoptera litura, and the parasitism rate was calculated; after the offspring bees emerged, they were allowed to die, and the number of emerging and female bees was counted, and the emergence rate and female ratio were calculated. Each group of treatments was repeated 10 times, and the calculation formula was referred to S2; S4. Data statistics and analysis: Excel software was used to summarize the data, and one-way analysis of variance was used in SPSS27.0 statistical software to test the effects of different parasitism times on the parasitism rate, offspring emergence rate and offspring female ratio of Spodoptera exigua; Tukey's method was used to compare the significance of differences among the groups.

[0008] As a further improvement of the present invention, the specifications of the glass finger tube are 12 mm in diameter and 75 mm in length.

[0009] As a further improvement of the present invention, the parameters of the artificial climate box are temperature of (27±1)°C, RH of (70±5)%, and photoperiod of (14L:10D).

[0010] As a further improvement of the present invention, the fresh eggs of Spodoptera litura are eggs within 0-12 hours.

[0011] As a further improvement of the present invention, the concentration of the honey water applied on the wall of the finger-shaped tube is 10%.

[0012] As a further improvement of the present invention, in S2, 10, 20, 40, 60 and 80 fresh eggs of Spodoptera litura of different densities are respectively introduced into the glass finger-shaped tubes.

[0013] As a further improvement of the present invention, in S3, 1, 2, 3, 4, and 5 female bees of the black egg wasp of Spodoptera litura that have mated within 12 hours of emergence are respectively introduced into the glass finger-shaped tube containing 60 fresh eggs of Spodoptera litura.

[0014] Beneficial effects of the present invention: With the increase of bee-egg ratio, the parasitism rate of Spodoptera litura on Spodoptera litura showed a trend of first increasing and then decreasing. When the bee-egg ratio was 1:40, the parasitism rate was the highest, and there was a significant difference between 1:60 and 1:80, indicating that when the single head of Spodoptera litura parasitized for 24 hours, its parasitism ability was about 86.67. The parasitism time had a significant effect on the parasitism rate of Spodoptera litura. The results showed that when the parasitism rate of Spodoptera litura was 24 hours, its parasitism ability was stronger. Similarly, the emergence rate and female ratio of the offspring of Spodoptera litura were significantly affected by the parasitism time and bee-egg ratio, and the emergence rate and female ratio of 48 hours and 72 hours were significantly higher than those of 24 hours. The parasitism of multiple Spodoptera litura on the parasitism rate, emergence rate and female ratio of Spodoptera litura had a certain effect, but there was no significant difference among the treatments. The results showed that the Spodoptera litura was not affected by its own density interference response.

[0015] The results of the present invention can be promoted and applied to the control of noctuid pests by the black egg wasp of the noctuid armyworm, which can effectively reduce the use of chemical pesticides, reduce the pesticide residues and plant protection costs of tomatoes, and increase the safety of tomatoes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the effects of different egg densities and parasitism time on the parasitism rate of Spodoptera exigua in the present invention; Figure 2 It is a schematic diagram of the effects of different egg densities and parasitism time on the emergence rate and female ratio of progeny of Noctuidae black egg wasp of the present invention; Figure 3 It is a schematic diagram of the influence of the self-density interference of the Noctuidae black egg wasp of the present invention on the parasitism rate, emergence rate and female ratio of the Noctuidae black egg wasp. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0018] The method for studying the parasitic ability of the noctuid black egg wasp to the cutworm includes the following steps: S1. Insect breeding: The black egg wasp of Spodoptera litura and Spodoptera litura were bred for the experiment. The black egg wasp of Spodoptera litura was sourced from the Institute of Plant Protection of Sichuan Academy of Agriculture and was subcultured at the Natural Enemy Propagation Center of the College of Agriculture of Guizhou University. The eggs of Spodoptera litura were used as hosts for breeding, and the adults were fed with 10% honey water and kept in an artificial climate chamber; Spodoptera litura was collected from Maling Township, Huaxi District, Guiyang City, Guizhou Province (26°16'40.4”N, 106°34'55.2”E), and was subcultured at the Natural Enemy Propagation Center of the College of Agriculture of Guizhou University. Spodoptera litura larvae were raised in 2.2L (22.5cm long × 15.5cm wide × 8cm high) fresh-keeping boxes, and fresh tobacco leaves were added daily to clean up food residues. After they pupated, they were transferred to rectangular egg-laying cages (45cm long × 30.8cm wide × 24.8cm high). 50 pupae were placed in each egg-laying cage. After the pupae emerged, a cotton ball wetted with 10% honey water was placed on the wire mesh as a nutritional supplement. At 9 am every day, check whether the female insects have laid eggs, collect the egg masses laid by the female insects every day, add honey water, and replace the egg-laying cloth. After three generations of continuous rearing, they were tested; Tobacco seeds were provided by Fenggang County Tobacco Company, and the variety was K326. The seeds were sown in plastic pots (18 cm in diameter × 19 cm in height), and a thin layer of nutrient soil was covered on the surface. Water was applied daily, and the pots were placed in a breeding room (28 ± 1 °C, 70 ± 5% RH, 14L: 10D) for cultivation. The tobacco plants were kept for later use after they grew to 15 cm and 30 cm in height, respectively. The main components of the nutrient soil are peat, perlite, vermiculite, and straw fermentation products. Insects and plants were raised separately to prevent the plants from being contaminated by insects, and the recovered substrate soil was placed outdoors for disinfection and sterilization. The breeding and experimental environmental conditions for all test insects in this experiment were (27 ± 1) °C, RH70% ± 5%, and a photoperiod of 14L: 10D; S2. Experimental response of the black egg wasp to the parasitic function of Spodoptera litura eggs of different densities: 10, 20, 40, 60, and 80 fresh eggs of Spodoptera litura (0-12h) of different densities were placed in glass finger-shaped tubes (diameter 12mm, length 75mm), and a female black egg wasp of Spodoptera litura that had mated within 12h of emergence was introduced. 10% honey water was smeared on the wall of the finger-shaped tube for the female bee to eat, and the tube was sealed with black cloth and rubber band; the tube was placed at a temperature of (27±1)℃, a RH of (70±5)%, and a photoperiod of (27±1)℃. The eggs were cultured in an artificial climate box with a temperature of (14L:10D); the female bees were removed after 24 hours, and the Spodoptera litura eggs were continued to be cultured under the same conditions. If any unparasitized eggs hatched during the culture process, the newly hatched larvae were removed in time to prevent them from eating the parasitized eggs; after 5 days of parasitism, the number of parasitized eggs was observed under a stereo microscope. If the eggs turned black, it meant that the eggs were parasitized by the black egg wasp of the Spodoptera litura, and the parasitism rate was calculated; after the offspring bees emerged, they died, and the number of emerging and female bees was counted, and the emergence rate and female ratio were calculated. Each group of treatments was repeated 10 times, and the calculation formula was: ; ; ; S3. Experiment on the interference effect of the density of Spodoptera litura: 1, 2, 3, 4, and 5 female Spodoptera litura black egg wasps that had mated within 12 hours of emergence were introduced into glass finger-shaped tubes (diameter 12 mm, length 75 mm) containing 60 fresh eggs of Spodoptera litura (0-12 hours). 10% honey water was applied to the wall of the finger-shaped tubes for the female bees to eat. The tubes were sealed with black cloth and rubber bands. The tubes were placed at a temperature of (27±1)℃, a RH of (70±5)%, and a photoperiod of (14L:10D). The female bees were removed after 24 hours, and the eggs of Spodoptera litura were cultured under the same conditions. If any unparasitized eggs hatched during the culture process, the newly hatched larvae were removed in time to prevent them from feeding on the parasitized eggs. After 5 days of parasitism, the number of parasitized eggs was observed under a stereomicroscope. If the eggs turned black, it meant that the eggs were parasitized by the black egg wasp of Spodoptera litura, and the parasitism rate was calculated. After the offspring bees emerged, they died, and the number of emerging and female bees was counted, and the emergence rate and female ratio were calculated. Each group of treatments was repeated 10 times, and the calculation formula was referred to S2. S4. Data statistics and analysis: Excel software was used to summarize the data, and one-way analysis of variance was used in SPSS27.0 statistical software to test the effects of different parasitism times on the parasitism rate, offspring emergence rate and offspring female ratio of Spodoptera exigua; Tukey's method was used to compare the significance of differences among groups, with the significance level of α=0.05.

[0019] Results and Analysis: The parasitic functional response of the black egg wasp of Spodoptera litura to different egg densities of Spodoptera litura: The effects of host egg density and parasitism time on the parasitism rate of Spodoptera exigua; Host egg density and parasitism time significantly affect the parasitism rate of Spodoptera exigua. With the increase of egg density and parasitism time, the parasitism rate shows a trend of first increasing and then decreasing. Figure 1 ), Note: Capital letters indicate significant differences between different host egg treatments, and lowercase letters indicate significant differences between different parasitism time treatments (P<0.05), the same below. At 24h of parasitism, the parasitism rate was the highest at 88.75% when the bee egg ratio was 1:40, which was not significantly different from 1:20 (81.50) and 1:60 (86.67), but significantly higher than 1:10 and 1:80 treatments (P<0.05); at 48h of parasitism, the parasitism rate was the highest at 93.00% when the bee egg ratio was 1:10, which was significantly higher than 1:60 and 1:80 treatments (P<0.05); at 72h of parasitism, the parasitism rates of bee egg ratios of 1:10, 1:40 and 1:60 were significantly higher than 1:80 treatment (P<0.05). When the bee-egg ratio was 1:10 and 1:60, the parasitism rate after 72h was significantly higher than that after 24h and 48h (P<0.05).

[0020] The effects of host egg density and parasitism time on the emergence rate and female ratio of offspring of Spodoptera exigua; Host egg density and parasitism time significantly affect the emergence rate and female ratio of offspring of Spodoptera exigua ( Figure 2 ). At 24h of parasitism, the emergence rate of the bee-egg ratio of 1:40 was the highest (92.04%), which was significantly higher than that of the 1:10 and 1:20 treatments (P<0.05), and the female ratio was not significantly different among the treatments; at 48h of parasitism, the emergence rate of the bee-egg ratio of 1:10 was significantly higher than that of 1:60 and 1:80 (P<0.05), and the female ratio of the bee-egg ratio of 1:10 (73.11%) was significantly lower than that of the other treatments (P<0.05); at 72h of parasitism, there was no significant difference in the emergence rate and female ratio of the offspring bees. At the bee-egg ratio of 1:20, 1:40 and 1:60, the emergence rate and female ratio of the offspring parasitized for 48h and 72h were significantly higher than those of the 24h treatment (P<0.05).

[0021] The black egg wasp's own density interference response: Under the influence of the density of the noctuid black egg wasp, the parasitism rate of the noctuid black egg wasp on the eggs of Spodoptera litura was above 86.67%, with the highest reaching 93.67% ( Figure 3 ). With the increase in the number of female noctuid black egg wasps, the parasitism rate showed a trend of first increasing and then decreasing, but the difference between treatments was not significant. Similarly, under the interference response of its own density, there was no significant effect on the offspring emergence rate and offspring female ratio of noctuid black egg wasps.

[0022] in conclusion: The results showed that with the increase of the bee-egg ratio, the parasitism rate of the noctuid black egg wasp on the Spodoptera litura showed a trend of first increasing and then decreasing. When the bee-egg ratio was 1:40, the parasitism rate was the highest, and there was a significant difference between 1:60 and 1:80, indicating that when the noctuid black egg wasp parasitized on a single head for 24 hours, its parasitism ability was about 86.67. The parasitism time had a significant effect on the parasitism rate of the noctuid black egg wasp. The results showed that when the parasitism rate of the noctuid black egg wasp was 24 hours, its parasitism ability was stronger. Similarly, the emergence rate and female ratio of the offspring of the noctuid black egg wasp were significantly affected by the parasitism time and the bee-egg ratio. The emergence rate and female ratio of 48 hours and 72 hours were significantly higher than those of 24 hours. The parasitism of multiple noctuid black egg wasps had a certain effect on the parasitism rate, emergence rate and female ratio of Spodoptera litura, but there was no significant difference among the treatments. The results showed that the noctuid black egg wasp was not affected by its own density interference response.

[0023] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for studying the parasitic ability of the noctuid black egg wasp to the cutworm, characterized in that: The following steps are involved: S1. Insect breeding: raising and breeding black egg wasps and Spodoptera litura for use in experiments; S2. Experimental parasitic functional response of the black egg wasp to different egg densities of Spodoptera litura: multiple groups of fresh eggs of Spodoptera litura with different densities were placed in glass finger-shaped tubes, and a female bee of the black egg wasp that had mated within 12 hours of emergence was introduced. Honey water was applied to the wall of the finger-shaped tube for the female bee to feed on, and the tube was sealed with black cloth and rubber bands; it was placed in an artificial climate chamber for cultivation; after 24 hours, the female bee was removed, and the eggs of Spodoptera litura continued to be cultured under the same conditions. If any unparasitized eggs hatched during the culture process, the newly hatched larvae were removed in time to avoid them from feeding on the parasitized eggs; after 5 days of parasitism, the number of parasitized eggs was observed under a stereo microscope. If the eggs turned black, it meant that the eggs were parasitized by the black egg wasp, and the parasitism rate was calculated; after the offspring bees emerged, they were waited for their death, and the number of emerging and female bees was counted, and the emergence rate and female ratio were calculated. Each group of treatments was repeated 10 times, and the calculation formula was: ； ； ； S3. Experiment on the interference effect of the density of the black egg wasp: Into glass finger-shaped tubes containing 60 fresh eggs of Spodoptera litura, different numbers of female bees of the black egg wasp of Spodoptera litura that had mated within 12 hours of emergence were introduced, and honey water was applied to the wall of the finger-shaped tubes for the female bees to feed on, and the tubes were sealed with black cloth and rubber bands; they were cultured in an artificial climate box; after 24 hours, the female bees were removed, and the eggs of Spodoptera litura continued to be cultured under the same conditions. If any unparasitized eggs hatched during the culture process, the newly hatched larvae were removed in time to avoid them from feeding on the parasitized eggs; after 5 days of parasitism, the number of parasitized eggs was observed under a stereo microscope. If the eggs turned black, it meant that the eggs were parasitized by the black egg wasp of Spodoptera litura, and the parasitism rate was calculated; after the offspring bees emerged, they were allowed to die, and the number of emerging and female bees was counted, and the emergence rate and female ratio were calculated. Each group of treatments was repeated 10 times, and the calculation formula was referred to S2; S4. Data statistics and analysis: Excel software was used to summarize the data, and one-way analysis of variance was used in SPSS27.0 statistical software to test the effects of different parasitism times on the parasitism rate, offspring emergence rate and offspring female ratio of Spodoptera exigua; Tukey's method was used to compare the significance of differences among the groups.

2. The method for studying the parasitic ability of the noctuid black egg wasp to the Spodoptera litura according to claim 1, characterized in that: The specifications of the glass finger tube are 12 mm in diameter and 75 mm in length.

3. The method for studying the parasitic ability of the noctuid black egg wasp to the Spodoptera litura according to claim 1, characterized in that: The parameters of the artificial climate box are temperature of (27±1)°C, RH of (70±5)%, and photoperiod of (14L:10D).

4. The method for studying the parasitic ability of the noctuid black egg wasp to the Spodoptera litura according to claim 1, characterized in that: The fresh eggs of Spodoptera litura are eggs within 0-12 hours.

5. The method for studying the parasitic ability of the noctuid black egg wasp to the Spodoptera litura according to claim 1, characterized in that: The concentration of honey water dotted on the wall of the finger-shaped tube is 10%.

6. The method for studying the parasitic ability of the noctuid black egg wasp to the Spodoptera litura according to claim 1, characterized in that: In the S2, 10, 20, 40, 60 and 80 fresh eggs of Spodoptera litura of different densities were respectively introduced into the glass finger tubes.

7. The method for studying the parasitic ability of the noctuid black egg wasp to the Spodoptera litura according to claim 1, characterized in that: In the S3, 1, 2, 3, 4, and 5 female bees of the black egg wasp of Spodoptera litura that had mated within 12 hours of emergence were respectively introduced into a glass finger-shaped tube containing 60 fresh eggs of Spodoptera litura.

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