A steinernema feltiae biological control agent for preventing and treating various pests and application thereof

Abstract

The application discloses a steinernema feltiae biological control agent for preventing and treating various pests and application thereof. The various pests include spodoptera litura, poplar leaf-feeding caterpillar, pea aphid and short horned locust. The application studies the infection activity difference of different strains of steinernema feltiae on four different agricultural pests, and understands the prevention and treatment effect of different strains of steinernema feltiae on different insects. Meanwhile, the application also studies the sensitivity difference of biological control natural enemy insects braconidae and serangium japonicum to steinernema feltiae, studies the infection activity on pests and the infection activity on natural enemy insects, and comprehensively discusses the application prospect of steinernema feltiae, which not only lays a foundation for the joint biological control of natural enemy insects and insect pathogenic nematodes, but also helps to determine the best application scene in agricultural production, and then improves the efficiency and overall effect of biological control, and better prevention and treatment effect can be produced when facing a complex harmful organism prevention and treatment environment.

Description

Technical Field

[0001] This invention relates to the field of biological control technology for pests, specifically to a biocontrol agent for controlling various pests, specifically the nematode Strychnos nudibranchii, and its application. Background Technology

[0002] Crop pests are one of the most significant disasters in my country's agricultural production, characterized by their diversity, wide impact, and frequent outbreaks. Their wide occurrence and severity often cause substantial losses to my country's national economy, especially agricultural production. The beet armyworm (Spodoptera litura) is one such pest. Spodoptera litura Armyworms, commonly known as flower worms or blackhead worms, belong to the family Noctuidae in the order Lepidoptera and are one of the major agricultural pests in my country. They have an extremely wide host range, covering 99 families and more than 290 plant species. They are intermittently occurring, voracious, and omnivorous pests. The larvae primarily feed on plant leaves, buds, flowers, and fruits. Their broad host range and voracious feeding characteristics have led to numerous devastating damages, posing a serious threat to agricultural production. Armyworms (… Mythimna separata The armyworm, also belonging to the Noctuidae family of Lepidoptera, is one of my country's major agricultural pests. It is widely distributed throughout China, except for Xinjiang. Its host plants are numerous, including cereal crops such as wheat, rice, millet, and corn, as well as cotton, beans, and various vegetables, totaling over 104 species from 16 families. The larvae primarily feed on plant leaves, and in large outbreaks, they can completely defoliate crops, causing severe damage. Armyworms are gregarious, migratory, omnivorous, and voracious, thus becoming a major agricultural pest nationwide. (The pea aphid is also mentioned.) Acyrthosiphonpisum The pea aphid, belonging to the family Aphididae in the order Hemiptera, is a major pest of peas, broad beans, alfalfa, and vetch. It can also damage legumes such as alfalfa, wild pea, and sweet clover, as well as other plants like shepherd's purse. The pea aphid is one of the largest aphids in the field, and in addition to directly damaging plants, it can also transmit various plant viruses, causing comprehensive damage. The short-horned outer-legged grasshopper (… Xenocatantops brachycerus The short-horned locust (Short-horned Locust) is a herbivorous insect that primarily feeds on plant leaves. Unlike most locusts that prefer grasses, the short-horned locust has a wide feeding range, encompassing various dicotyledonous plants such as paulownia, raspberry, peach, knotweed, ailanthus, and sumac. Its broad diet makes it a significant potential threat to agroforestry ecosystems. For a long time, numerous emergency measures have been implemented both domestically and internationally, including the use of various pyrethroids, organophosphates, Bt formulations, and various field control measures. While these measures have killed many natural enemies, they have reduced the safety of agricultural products and led to pesticide resistance in the pests, hindering the sustainable development of agricultural production in my country. Due to their wide host range, voracious feeding habits, and significant damage to agricultural production, these pests have become a critical target requiring urgent control.

[0003] Currently, the control of these pests in China mainly relies on several new chemical insecticides with strong insecticidal activity, such as emamectin benzoate, chlorantraniliprole, spinosad, and their related compound formulations, which have achieved certain control effects in production. However, long-term and large-scale application of chemical pesticides not only leads to environmental pollution but also easily promotes pesticide resistance in pests. With the advancement of science and technology, and considering long-term environmental and health benefits, biological control methods, such as the application of entomopathogenic nematodes, are becoming an important direction for sustainable pest control.

[0004] Entomopathogenic nematodes are an important biological control resource that can exclusively infect and parasitize insects. Their main species include the genus *Strombaeus* (…). Steinernema ) and Heterobalacillus ( ) Heterorhabditis These nematodes possess a wide host range and strong active searching ability, enabling them to effectively locate and parasitize target pests. They also offer advantages such as being environmentally friendly, safe for humans and animals, easy to cultivate, and low-cost. Furthermore, they can be mixed with chemical pesticides to enhance control efficacy. Although studies have reported good control effects of entomopathogenic nematodes against certain specific pests, different entomopathogenic nematodes exhibit varying infectivity against different pests, and different strains of the same entomopathogenic nematode also show differences in infectivity against different pests. Therefore, studying the infectivity of different species or strains of nematodes against different insects helps to understand their control spectrum and dominant targets, allowing for better realization of their biological control potential. Summary of the Invention

[0005] The purpose of this invention is to provide biological control methods for various pests.

[0006] To achieve the above objectives, the present invention first provides a new use for the noctuid moth nematode.

[0007] This invention provides the application of the noctuid moth nematode, Stellaria dichotoma, in pest control; the pests are beet armyworm and / or armyworm and / or pea aphid and / or short-horned grasshopper.

[0008] This invention also provides the application of the noctuid moth *Spodoptera litura* in the preparation of products for the control of pests; the pests being *Spodoptera litura* and / or armyworms and / or pea aphids and / or short-horned grasshoppers.

[0009] To achieve the above objectives, the present invention provides new uses for the noctuid moth nematode and its natural enemy insects.

[0010] This invention provides the application of the noctuid moth nematode and its natural enemy insects in pest control; the natural enemy insects include the flower beetle and / or the tube-shaped parasitic wasp.

[0011] This invention also provides the application of the noctuid moth Strømsgod nematode and its natural enemies in the preparation of products for pest control; the natural enemies include the flower beetle and / or the tube-shaped parasitic wasp.

[0012] Furthermore, the pests include the noctuid moth Stellariae nematode, which can control pests, and / or natural enemy insects, which can control pests.

[0013] Furthermore, the pests that the noctuid moth nematode can control include noctuid moths, aphids, locusts, and fruit flies.

[0014] The natural enemy insects that can control pests include the flower beetle and / or the tube-shaped parasitic wasp.

[0015] Furthermore, the noctuid pests include the beet armyworm, the armyworm, and the fall armyworm.

[0016] The aphids mentioned include the pea aphid.

[0017] The locust pests mentioned include the short-horned outer-legged locust.

[0018] The flower-like parasitic beetle can control pests including longhorn beetles, such as the Chinese arborvitae longhorn beetle, the pine longhorn beetle, the mulberry longhorn beetle, and the rusty-shouldered longhorn beetle, etc.

[0019] The *Sclerodermus guani* wasp can control pests including stem borers, such as longhorn beetles on pine, poplar, peach, apricot, plum, and various fruit trees.

[0020] To achieve the above objectives, the present invention also provides a composition for controlling pests.

[0021] The composition for pest control provided by the present invention includes the noctuid moth Strømsgodon nematode and its natural enemies; the natural enemies include the flower beetle and / or the tube-shaped parasitic wasp.

[0022] Furthermore, the composition also includes deionized water.

[0023] The application of the above composition in the prevention and control of pests or in the preparation of products for the prevention and control of pests is also within the scope of protection of this invention.

[0024] To achieve the above objectives, the present invention finally provides a method for controlling pests.

[0025] The method for controlling pests provided by this invention is as follows: 1) or 2):

[0026] 1) The method includes the following steps: applying the noctuid nematode Stellariae to the pest; the pest is the beet armyworm and / or armyworm and / or pea aphid and / or short-horned grasshopper;

[0027] 2) The method includes the following steps: applying the noctuid nematode Stellariae and its natural enemies to the pests; the natural enemies include the flower beetle and / or the tube-shaped parasitic wasp; the pests include the above-mentioned noctuid nematode Stellariae to control the pests and / or the above-mentioned natural enemies to control the pests.

[0028] In method 1) above, the method of applying Stellaria dichotoma to pests can be to drop a suspension of Stellaria dichotoma onto the surface of the pest larvae or to drop a suspension of Stellaria dichotoma onto a container (plastic box or cup) containing the pests.

[0029] Furthermore, the suspension of *Strombus schoensis* can be a nematode suspension obtained by mixing *Strombus schoensis* with a solvent.

[0030] Furthermore, the solvent may be deionized water.

[0031] In method 1) above, when the pest is *Spodoptera litura*, the ratio of the *Spodoptera litura* SF-SN strain to the *Spodoptera litura* can be 25-400 *Spodoptera litura* SF-SN strains to 1 *Spodoptera litura* larva; preferably 44 *Spodoptera litura* SF-SN strains to 1 *Spodoptera litura* larva. The ratio of the *Spodoptera litura* IGA strain to the *Spodoptera litura* can be 25-400 *Spodoptera litura* IGA strains to 1 *Spodoptera litura* larva; preferably 43 *Spodoptera litura* IGA strains to 1 *Spodoptera litura* larva.

[0032] When the pest is an armyworm, the ratio of the *Strombus schoenleinii* SF-SN strain to the armyworm larva can be 25-400 *Strombus schoenleinii* SF-SN strain to 1 armyworm larva; preferably 395 *Strombus schoenleinii* SF-SN strain to 1 armyworm larva. The ratio of the *Strombus schoenleinii* IGA strain to the armyworm larva can be 25-400 *Strombus schoenleinii* IGA strain to 1 armyworm larva; preferably 393 *Strombus schoenleinii* IGA strain to 1 armyworm larva.

[0033] When the pest is the pea aphid, the ratio of the *Strombus schoenleinii* SF-SN strain to the pea aphid can be 25-400 *Strombus schoenleinii* SF-SN strains to 1 wingless adult pea aphid; preferably 28 *Strombus schoenleinii* SF-SN strains to 1 wingless adult pea aphid. The ratio of the *Strombus schoenleinii* IGA strain to the pea aphid can also be 25-400 *Strombus schoenleinii* IGA strains to 1 wingless adult pea aphid; preferably 20 *Strombus schoenleinii* IGA strains to 1 wingless adult pea aphid.

[0034] When the pest is *Spodoptera shorthornata*, the ratio of *Strombus spp.* SF-SN strain to *Spodoptera shorthornata* can be 25-400 *Strombus spp.* SF-SN strains to 1 adult *Spodoptera shorthornata*; preferably 56 *Strombus spp.* SF-SN strains to 1 adult *Spodoptera shorthornata*. The ratio of *Strombus spp.* IGA strain to *Spodoptera shorthornata* can also be 25-400 *Strombus spp.* IGA strains to 1 adult *Spodoptera shorthornata*; preferably 54 *Strombus spp.* IGA strains to 1 adult *Spodoptera shorthornata*.

[0035] In any of the methods or applications described above, the control of pests is manifested in increasing the mortality rate of pests.

[0036] In any of the methods or applications described above, the *Steinus spp.* is the infecting stage of *Steinus spp.*

[0037] In any of the methods or applications described above, the *Strombyx mori* nematode is the *Strombyx mori* SF-SN strain or the *Strombyx mori* IGA strain.

[0038] In any of the methods or applications described above, the beet armyworm is a beet armyworm larva, preferably a 5th instar beet armyworm larva.

[0039] In any of the methods or applications described above, the armyworm is an armyworm larva, preferably a 5th instar armyworm larva.

[0040] In any of the methods or applications described above, the pea aphid is an adult pea aphid, preferably a wingless adult pea aphid.

[0041] In any of the methods or applications described above, the short-horned outer-legged grasshopper is an adult short-horned outer-legged grasshopper.

[0042] Any of the products mentioned above may be biocontrol reagents.

[0043] This invention, through the cultivation and reproduction of the nematode *S. spp.*, and the application of different doses and strains of *S. spp.* suspension to *S. beet armyworm*, *Armorworm*, *Pediatric aphid*, and *Exotropis shorthorn* locust, investigated the infectivity of *S. spp.* nematode against these pests. This study is the first to demonstrate that *S. spp.* nematode can effectively control these pests, demonstrating its broad application value in the field of biological control of field pests. Furthermore, this invention investigated the sensitivity differences between the biocontrol natural enemies *S. spp.* nematode and *Parasitic spp.* nematode. It found that these two biocontrol natural enemies were insensitive to both the SN and IGA strains of *S. spp.* nematode. The lack of infectivity of *S. spp.* nematode against these natural enemies suggests that the combined use of natural enemies and entomopathogenic nematodes for biological control of pests has promising application prospects.

[0044] Beneficial effects of this invention:

[0045] 1. This invention investigated the differences in infectivity of different strains of *Skesneferi noctuida* against four different agricultural pests, revealing the control effects of different strains on various insects. This helps to uncover its advantages and control spectrum in specific pest control, optimize nematode screening and application strategies, and achieve more precise biological control of pests. It has significant practical implications for reducing reliance on chemical pesticides, developing more effective integrated pest management strategies, and protecting the ecological environment.

[0046] 2. This invention studies the infectivity of pests and the infectivity of natural enemy insects, and comprehensively discusses the application prospects of the noctuid moth Strømsgoddess. This not only lays the foundation for the combined biological control of natural enemy insects and entomopathogenic nematodes, but also helps to clarify its optimal application scenarios in agricultural production, thereby improving the efficiency and overall effect of biological control, especially in the face of complex pest control environments, where it will produce better control effects. Attached Figure Description

[0047] Figure 1 The infection activity of different doses of *Spodoptera litura* nematode against *Spodoptera litura*. Note: Left: SF-SN strain; Right: IGA strain.

[0048] Figure 2 The infectivity of different doses of *Strombus schoenleinii* to armyworms is shown. Note: Left: SF-SN strain; Right: IGA strain.

[0049] Figure 3 The infectivity of different doses of *Strombus skeletoni* nematode against pea aphids. Note: Left: SF-SN strain; Right: IGA strain.

[0050] Figure 4 The infection activity of different doses of *Strombus steggii* nematode against *Exotrichum septemlobus*. Note: Left: SF-SN strain; Right: IGA strain.

[0051] Figure 5 The infection activity of different strains of *Strombus squarrosa* against *Hypericum fasciatus* and *Symplocos guanis* wasp. Note: *Hypericum fasciatus* is on the left, and *Symplocos guanis* is on the right. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0053] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0054] The following examples of the noctuid moth nematode S.feltiae The IGA strain is described in the literature “Li Chunjie, Wang Xinpeng, Huang Minghui, et al. Molecular identification of entomopathogenic nematodes [J]. Soil and Crops, 2020, 9(4): 380-387”.

[0055] The following examples of the noctuid moth nematode S.feltiae The SF-SN strain is a product of Weifang Hongrun Agricultural Technology Co., Ltd.

[0056] The 5th instar larvae of the beet armyworm and the 5th instar larvae of the armyworm in the following examples are products of Henan Jiyuan Baiyun Industrial Co., Ltd.

[0057] The wingless adult pea aphid and the adult short-horned grasshopper in the following examples were obtained by identification after being collected in the wild (Nanyang, Henan).

[0058] The tube-shaped swollen leg bee in the following embodiments Scleroderma guani Xiao et Wu and Huarongjijia Dastarcus helophoroides All are products of Henan Jiyuan Baiyun Industrial Co., Ltd.

[0059] Example 1: Study on the infectivity of *Spodoptera litura* against *Spodoptera litura*, armyworm, pea aphid, and *Exodontidae spicata*.

[0060] I. Rearing of the Noctuid Nematode and Other Pests

[0061] 1. Rearing of the Noctuid nematode Stellariae

[0062] The *Strombus skeletalus* nematode was artificially cultured and propagated indoors using the *Strombus skeletalus* as the insect host. The specific method is as follows: Twenty mature *Strombus skeletalus* larvae were placed in a sterilized nematode infection box lined with double layers of gauze. A nematode suspension of a certain concentration, prepared by mixing the infecting stage *Strombus skeletalus* nematodes with deionized water, was dripped onto the surface of the mature *Strombus skeletalus* larvae, causing continuous infection. After 3 days, the dead *Strombus skeletalus* nematodes were transferred to 6cm petri dishes lined with double layers of filter paper, with 2-3 dead nematodes in each dish. These smaller petri dishes containing dead nematodes were then placed in a 9cm petri dish containing deionized water and placed in a dark nematode incubator at 25℃ and 65±5% humidity. After 7 days, the progeny infecting *Strombus skeletalus* nematodes crawled from the dead *Strombus skeletalus* nematodes into the water in the larger petri dish. The water in the larger petri dish was collected into 50ml centrifuge tubes, and the nematodes were collected after repeated sedimentation three times. The collected nematodes were placed in cell culture flasks for future use.

[0063] II. Effects of different doses and strains of *Spodoptera litura* on the infectivity of *Spodoptera litura*, armyworm, pea aphid, and *Spodoptera litura*.

[0064] 1. Experimental Methods

[0065] 1) Preparation of suspension of *Strombus skeletalus* (a type of nematode)

[0066] The SF-SN strain of the noctuid moth skeletal nematode was mixed with deionized water to prepare SF-SN nematode suspensions with concentrations of 250 IJs / mL, 500 IJs / mL, 1000 IJs / mL, 2000 IJs / mL, 3000 IJs / mL, and 4000 IJs / mL.

[0067] The IGA strain of the infecting moth nematode was mixed with deionized water to prepare IGA nematode suspensions with concentrations of 250 IJs / mL, 500 IJs / mL, 1000 IJs / mL, 2000 IJs / mL, 3000 IJs / mL, and 4000 IJs / mL.

[0068] 2) Infection methods of the beet armyworm

[0069] In a 12-well plate lined with 2.5cm of moistened filter paper, add 0.5cm×0.5cm samples of *Spodoptera litura* feed (composed of 8.1g soybean flour, 3.8g wheat germ flour, 3.3g yeast powder, 1.3g agar, 0.5g preservative, 0.3g antifungal agent, and 82.7g water) to each well. Select relatively uniform 5th instar *Spodoptera litura* larvae and place one larva in each well to create a *Spodoptera litura* infection system. Then, add 100μL of SF-SN nematode suspension or IGA nematode suspension of different concentrations to each well, so that the ratio of *Spodoptera litura* nematodes to *Spodoptera litura* larvae is 25:1, 50:1, 100:1, 200:1, 300:1, and 400:1, respectively.

[0070] 3) Methods of infection by armyworms

[0071] In a 12-well plate lined with 2.5cm of moistened filter paper, add 0.5cm×0.5cm×0.5cm portions of armyworm feed (composed of 8g soybean flour, 4g yeast powder, 4.5g wheat flour, 6.5g corn flour, 0.35g acetic acid, 0.35g ascorbic acid, 0.075g benzoic acid, 0.25g sodium benzoate, 0.062g cholesterol, 1.8g agar, and 77g water). Select relatively uniform 5th instar armyworm larvae and place them into different 12-well plates, one larva per well, to create an armyworm infection system. Then, add 100μL of SF-SN nematode suspension or IGA nematode suspension of different concentrations to each well, so that the ratio of *Strombyx mori* nematode to armyworm larvae is 25:1, 50:1, 100:1, 200:1, 300:1, and 400:1, respectively.

[0072] 4) Methods of infection by pea aphids

[0073] Fresh broad bean stems and leaves were added to a 5cm sauce cup lined with moistened filter paper. Wingless adult pea aphids of relatively uniform size were selected and placed into the cup, with 10 aphids per cup, to create a pea aphid infection system. Then, 1000μL of different concentrations of SF-SN nematode suspension or IGA nematode suspension were added to each well, so that the ratio of Stellaria dichotoma nematode to wingless adult pea aphids was 25:1, 50:1, 100:1, 200:1, 300:1, and 400:1, respectively.

[0074] 5) Infection methods of the short-horned outer-legged locust

[0075] Add an appropriate amount of fresh alfalfa to a 9 cm plastic box lined with moistened filter paper. Select relatively uniform-sized adult short-horned grasshoppers and place them into the plastic box, with 10 grasshoppers in each box, to create a short-horned grasshopper infection system. Then, add 1000 μL of different volumes of SF-SN nematode suspension or IGA nematode suspension to each box, so that the ratio of *Strombus styrax* nematode to adult short-horned grasshoppers is 25:1, 50:1, 100:1, 200:1, 300:1, and 400:1, respectively.

[0076] Ten insects constituted one replicate, with three replicates per treatment dose. For *Spodoptera litura*, armyworm, and *Spodoptera exigua*, death was defined as no response to needle pricks; for *Pediatric aphid*, death was defined as no response to brush touch. Mortality was observed and recorded every 12 hours for a total of 7 days. A control group containing the same dose of deionized water was used. After 7 days, the corrected mortality rate and LC50 (median lethal concentration) were calculated. The culture environment was an RXZ-500B intelligent artificial climate chamber with a photoperiod of 14L:10D, a temperature of 25℃, and a humidity of 65±5%. Corrected mortality rate = [(treatment mortality rate - control mortality rate) / (1 - control mortality rate)] × 100%.

[0077] 2. Experimental Results

[0078] 1) Mortality rate

[0079] By statistically analyzing the mortality rates of four insect species after different infestation times with different doses of *Strombyx mori*, it was found that the mortality rate of *Strombyx mori* against *Spodoptera litura*, armyworm, pea aphid, and short-horned grasshopper increased with increasing nematode dosage. Figures 1-4 Among them, the corrected mortality rate of the beet armyworm infected with nematodes can reach 100% at a medium concentration (100 IJs / insect), and the corrected mortality rate can also approach 20% at a low concentration (25 IJs / insect). Figure 1 The corrected mortality rate of armyworms infected with high concentrations (300 IJs / head) of *Strombiella stearothermiae* nematodes reached a maximum of 53.33% after 7 days, while the corrected mortality rate under low concentrations (25 IJs / head) of nematodes was less than 5%. Figure 2 The corrected mortality rate of pea aphids can reach 100% in medium-concentration (100 IJs / aphid) nematode infestation, and the corrected mortality rate is around 50% in low-concentration (25 IJs / aphid) nematode infestation. Figure 3 The corrected mortality rate of *Spodoptera litura* infected with different concentrations of *Strombus skeletoni* ranged from 20% (25 IJs / head) to 100% (100 IJs / head and above). Figure 4 The above results indicate that the noctuid nematode *Spodoptera litura* has a good control effect on beet armyworm, armyworm, pea aphid, and short-horned grasshopper, among which the SF-IGA strain has a relatively better control effect than the SN strain.

[0080] 2) LC50 value

[0081] Statistical analysis of the LC50 values ​​of *Strombus spp.* (a type of nematode) against four insect species revealed the following: The SF-SN strain of *Strombus spp.* had a median lethal concentration (LC50) of 44:1 against *Spodoptera litura*; 56:1 against *Exodontidae spp.*; 395:1 against *Armoriae spp.*; and 28:1 against pea sprouts. The IGA strain of *Strombus spp.* had a LC50 of 43:1 against *Spodoptera litura*; 54:1 against *Exodontidae spp.*; 393:1 against *Armoriae spp.*; and 20:1 against pea sprouts.

[0082] Table 1. LC50 values ​​of *Strombus skeletoni* against four insects.

[0083]

[0084] Note: Different superscript letters in the same column indicate significant differences between the two treatments (SN and IGA) (p < 0.05).

[0085] Example 2: Study on the infection activity of *Strombus steggii* nematode against *S. tuberculosis* and *S. truncatula*.

[0086] Flower-shaped nail Dastarcus helophoroides Guan's swollen leg bee Scleroderma guani Xiao et Wu are both natural enemy insects and are commonly used biological control materials. These biological materials each have their own characteristics in biological control. For example, the flower-like parasitic beetle can be used to control longhorn beetles such as the Chinese arborvitae longhorn beetle, the pine sawyer beetle (a carrier of pine wood nematodes), the mulberry longhorn beetle, and the rust-colored grain-shouldered longhorn beetle. The tube-like parasitic wasp can be used to control stem-boring pests such as longhorn beetles on pine, poplar, peach, apricot, plum, and various fruit trees. The noctuid moth nematode (Stokes bovis) differs significantly from these biological control pests. To investigate the difference in sensitivity between the tube-like parasitic wasp and the flower-like parasitic beetle to the noctuid moth nematode, a natural infection experiment was conducted on adult tube-like parasitic wasps and flower-like parasitic beetles using the SN and IGA strains of the noctuid moth nematode under laboratory conditions. The specific steps are as follows:

[0087] I. Experimental Methods

[0088] 1. Preparation of nematode suspension

[0089] Nematode suspensions with a concentration of 10,000 IJs / mL were prepared by mixing the SN and IGA strains of the infecting nematode Strychnine with deionized water.

[0090] 2. Infection by the noctuid moth nematode.

[0091] (1) Natural infection of the flower velvet parasite

[0092] Moistened filter paper was placed in breathable sauce cups, and 10 relatively uniform-sized parasitic nematodes were placed inside. 100 μL of nematode suspension at a concentration of 10000 IJs / mL was added to each sauce cup. The control group received the same amount of deionized water. Three replicates were set up. The sauce cups were placed in an artificial climate chamber (L:D=0:24, 25℃, RH=60±5%). Mortality was observed every 24 hours, with no reaction upon touch with tweezers as the criterion for death. The observation period lasted for 4 days.

[0093] (2) Natural infection of *Scleroderma kusnezoffii*

[0094] Line 1.5 ml centrifuge tubes with moistened filter paper, and place 10 relatively uniform-sized *S. tuberoideae* nematodes into each tube. Add 100 μL of nematode suspension at a concentration of 10000 IJs / mL to each tube. The control group was treated with the same amount of deionized water. Three replicates were set up. The centrifuge tubes were placed in an artificial climate chamber (L:D=0:24, 25℃, RH=60±5%), and mortality was observed every 24 hours. Death was defined as no reaction when touched by a brush. The observation period was 4 days.

[0095] II. Experimental Results

[0096] The results are as follows Figure 5 As shown, the results indicate that with increasing infection time, the corrected mortality rates of both the flower-like parasitic beetle and the tube-shaped swollen leg wasp infected with the nematode were zero, indicating that these two insects are insensitive to both the SN and IGA strains of *Strombus skeletoni*. Therefore, in complex pest control environments, a combined biological control approach can be adopted, leveraging the advantages of natural enemy insects and entomopathogenic nematodes. The fact that *Strombus skeletoni* lacks infectivity against these natural enemy insects makes this combined control strategy promising and likely to produce better control effects.

[0097] The present invention has been described in detail above. For those skilled in the art, the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. Although specific embodiments have been given, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein. Some of the essential features can be applied within the scope of the following appended claims.

Claims

1. Application of the noctuid moth Strømsgoddess in pest control or in the preparation of pest control products; The pests are pea aphids and / or short-horned grasshoppers; The *Strombus schoensis* strain is either the SF-SN strain or the IGA strain.

2. The application according to claim 1, characterized in that: The control of pests is reflected in increasing the mortality rate of pests.

3. Application of the noctuid moth nematode and its natural enemies in the control of pests or the preparation of pest control products; The pests are pea aphids and / or short-horned grasshoppers; The natural enemy insects include the flower-like parasitic beetle and / or the tube-shaped parasitic wasp; The *Strombus schoensis* strain is either the SF-SN strain or the IGA strain.

4. Application of the composition in the control of pests or in the preparation of products for the control of pests; The composition includes the noctuid moth Stöhrne nematode and its natural enemy insects; The natural enemy insects include the flower-like parasitic beetle and / or the tube-shaped parasitic wasp; The *Strombyx mori* strain is either the *Strombyx mori* SF-SN strain or the *Strombyx mori* IGA strain. The pests mentioned are pea aphids and / or short-horned grasshoppers.

5. A method for controlling pests, comprising: 1) or 2): 1) The method includes the following steps: applying the noctuid nematode Stellariae to the pest; 2) The method includes the following steps: applying the noctuid moth nematode and its natural enemy insects to the pest; The pests are pea aphids and / or short-horned grasshoppers; The *Strombus schoensis* strain is either the SF-SN strain or the IGA strain.

Images