A natural enemy conservation transfer method for constructing a natural enemy annual cycle transfer system in southern rice fields by using perennial legumes

Abstract

The application discloses a natural enemy conservation transfer method for constructing a natural enemy annual circulation transfer system in a southern rice field by using perennial leguminous plants. In a rice field ridge or a machine plough way or other non-agricultural habitats, alfalfa is planted at a suitable time, and a multi-natural enemy storage plant system is constructed by using alfalfa and local functional weeds in the alfalfa planting area, so that the natural enemies are conserved and the natural enemy source base in the rice field is effectively increased; the alfalfa flowering period is adjusted to match the key growth period of rice pest control in the southern rice field; and the storage plants are actively cut at a specific time, so that the natural enemies are promoted to transfer between the rice field and the storage plant system. The application conserves the natural enemies by increasing the natural enemies in the rice field before the rice tillering period and before the main pest generation of the brown planthopper, and for the first time constructs a natural enemy annual circulation transfer system to conserve the natural enemies, increase the natural enemy population quantity, enhance the natural control ability of the rice field, reduce the prevention and control pressure of the main pest generation of the brown planthopper, and solve the problems of the few natural enemies in the early stage of the rice field and the slow population establishment.

Description

Technical Field

[0001] This invention relates to the field of biological control of rice paddy pests, specifically to a method for the conservation and transfer of natural enemies using a perennial leguminous plant-based system for the year-round cyclical transfer of natural enemies in southern rice paddies. Background Technology

[0002] For a long time, pesticides have been a habitual input in rice production in my country, regardless of scale (Wang Yong and He Bingjun, 2006). However, excessive pesticide use has also led to a serious deterioration of pest problems, such as pest resistance, pesticide residues, and rampant resurgence of pests (Heong KL & Hardy B., 2009; Wu Kongming, 2018).

[0003] The basic characteristics of brown planthopper outbreaks in rice-growing areas of northern Zhejiang in the Yangtze River Delta region have consistently been low initial influx numbers followed by high population growth rates in the later stages. A certain level of influx lays the foundation for brown planthopper outbreaks, while abnormally high population growth rates are key to outbreaks (Cheng Jia'an and Zhu Zengrong, 2006). Long-term frequent use of pesticides has led to increased pesticide resistance in brown planthoppers, making them difficult to control and frequently resulting in planthopper burns or even entire fields of lodging. With the expansion and development of modern agriculture, the fragmentation and homogenization of farmland habitats are increasing (Rand and Tscharntke, 2007), leading to a decrease in the number of biological species, including natural enemy insects (Kruess and Tscharntke, 1994), and reducing the effectiveness of biological control (Thies and Tscharntke, 1999).

[0004] Conserving natural enemies to reduce pesticide use is a current consensus in pest control. However, for a long time, the conservation of natural enemies for rice paddy pests has been done starting from the rice planting season. The accompanying effect of the population density of natural enemies and pests means that the development of natural enemies in farmland always lags behind that of pests. Natural enemies reach their peak before rice harvest, but most of them are killed and depleted as the crop is harvested. This is the case year-round in rice-wheat rotation areas or subtropical rice-growing areas, making pesticides indispensable for rice paddy pest control, thus creating a vicious cycle: the more pesticides used, the fewer natural enemies there are, the more difficult it is to control pests, and the more pesticides are used. The rotation of cropping systems often leads to the interruption of natural enemy conservation in farmland. To date, all inventions, papers, and other reported natural enemy conservation measures have failed to overcome the problem of the interruption of natural enemy conservation caused by crop rotation in cropping systems. The concept and method of a year-round natural enemy cycle system have not yet been reported in this field. How to break the cycle of pests and natural enemies in conventional rice production, and how to establish an annual cycle system for paddy fields under subtropical rice-wheat or rice-rapeseed double cropping systems, remains an unsolved ultimate problem.

[0005] Furthermore, besides the drawbacks of cultivating nectar-producing plants to conserve natural enemies starting from the rice planting season, relying on government subsidies and government mandates for farmers to cultivate them lacks intrinsic motivation or willingness. Without voluntary cultivation by farmers, the conservation of natural enemies is difficult to promote comprehensively and deeply. The root cause is that the cultivated nectar-producing plants have low economic value and are unrelated to the local dominant industries. This patent, based on solving the ultimate technical problem of natural enemy recycling, extends the industrial chain of conservation plant utilization from the perspective of value utilization, providing an innovative solution. Summary of the Invention

[0006] To address the problems existing in the background technology, this invention provides a method for the transfer and conservation of crop natural enemies using perennial leguminous plants to construct a year-round natural enemy cycle system in southern rice paddies. This invention addresses this challenge by introducing new conservation plants into southern rice-growing areas, constructing a conservation plant complex, and establishing a complete year-round natural enemy cycle system in rice paddies. By enhancing the natural control effect of natural enemies in the early stages, and during the establishment of populations of the brown planthopper (which cannot overwinter natively in subtropical rice-growing areas) after its migration, the invention increases the population of natural enemies through conservation, strengthens natural control capabilities, and reduces the control pressure on the dominant brown planthopper generation. Simultaneously, by utilizing the value of conservation plants, a new industrial chain for the utilization of conservation plants is established, leveraging the endogenous driving force and enthusiasm for the cultivation of conservation plants.

[0007] The technical solution adopted in this invention is: The specific method for constructing a year-round cyclical transfer system of natural enemies in southern rice paddies using perennial leguminous plants involves: planting alfalfa at the designated sowing time along rice paddy ridges, farm roads, or in non-agricultural habitats other than ridges and farm roads; constructing a multi-natural enemy reserve system with native functional weeds in the alfalfa planting area; adjusting the alfalfa flowering period to match the critical growth period for pest control in wheat or rice planted in the farmland; and artificially inducing the transfer of natural enemy populations to the farmland through active mowing of the reserve system, thus achieving pesticide-free control; during wheat or rice harvesting, the natural enemies migrate from the farmland to the reserve system, allowing for mutual transfer between the rice paddies and the reserve system, thus enabling the reserve plants to conserve natural enemies and achieve complete control of rice planthoppers without the need for chemical pesticides.

[0008] Through sowing period regulation and active mowing management, a directed and controllable cycle of natural enemies is established between the "storage plant system ↔ farmland," specifically including: (1) Timing matching layer: By controlling spring or autumn sowing, the flowering / harvest period of the storage plants is precisely aligned with the key growth periods of wheat and rice three times; alfalfa or yellow alfalfa and local functional weeds in the planting area construct a storage plant system with multiple natural enemies.

[0009] (2) Active transfer layer: Active mowing is carried out during the flowering period or specific growth period of the storage plants; the natural enemies are quickly transferred to the farmland by physical means of patting and mowing; the stubble height is controlled at 5-7cm to prepare for the next cycle.

[0010] (3) Passive receiving layer: When wheat or rice is harvested, the storage plants are in a vigorous growth period; automatically receiving the natural enemy groups that migrate out when the crops are harvested; continuously protecting them until the next crop is planted.

[0011] (4) Cyclic characteristics: Realize the annual continuous cycle of "storage plant storage and conservation → transfer 1 to crop 1 → crop 1 utilization → transfer 2 back to storage plant → storage plant storage and conservation → transfer 3 to crop 2 → crop 2 utilization → transfer back to storage plant".

[0012] The specific methods for the transfer and conservation of crop natural enemies are as follows: S1. Arrange an appropriate sowing period to plant alfalfa. The alfalfa grows together with the native functional weeds in the alfalfa planting area to construct a storage plant system of multiple natural enemies, so that the flowering period of alfalfa matches the key growth period of wheat or rice planted in the farmland for the purpose of conservation and transfer of natural enemies. S2. The first flowering period of alfalfa overlaps with the jointing and heading stage of wheat. The flowers of alfalfa provide pollen, attracting natural enemies to migrate to the storage plant system, thereby protecting the natural enemies. When wheat is heading, alfalfa is harvested for the first time, prompting the natural enemies protected in the storage plant system to transfer to the farmland, thereby controlling pests in the farmland. The alfalfa continues to grow until wheat is harvested, allowing the storage plant system to take in the natural enemies that migrate out of the farmland after wheat harvest and to protect the natural enemies. S3. Control the sowing time of rice in the field so that the second flowering period of alfalfa is before the tillering period of rice. Carry out the second harvest of alfalfa to encourage the transfer of natural enemies on alfalfa to rice fields, provide a natural enemy pool for the middle and late stages of rice growth, and promote the establishment of natural enemy populations in rice fields in the early stage. S4. When the third flowering period of alfalfa overlaps with the heading period of rice, the third harvest is carried out to encourage the transfer of newly generated natural enemies from alfalfa to the paddy field, providing a natural enemy pool for the paddy field in the later stage of rice growth and controlling the main pest, rice planthopper.

[0013] 3. The method for the conservation and transfer of natural enemies using perennial leguminous plants to construct a year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 2, is characterized in that... The farmland is a southern paddy field; the alfalfa is one or more of alfalfa purple and alfalfa yellow; the alfalfa purple is one or more of WL525, Algonquin, and Triple Play; the alfalfa yellow is large-leaved alfalfa; the native functional weeds are one or more of zoysia grass, cogongrass, foxtail grass, bermudagrass, wild oats, and purslane; the key growth periods of wheat are the jointing and booting stage and the heading stage, and the key growth periods of rice are the tillering stage and the booting stage.

[0014] Each flowering period of the alfalfa is divided into two stages: the initial flowering stage and the full flowering stage. When the alfalfa is purple alfalfa, the first harvest of alfalfa in step S2 is carried out during the initial flowering stage of purple alfalfa; the second harvest of alfalfa in step S3 is carried out during the initial flowering stage of purple alfalfa; and the third harvest in step S4 is carried out during the flowering stage of alfalfa. After harvesting, it is used as feed for lake sheep.

[0015] When the alfalfa is yellow alfalfa, the first alfalfa harvest in step S2 is carried out 35-40 days after sowing; the second alfalfa harvest in step S3 is carried out during the initial flowering stage of yellow alfalfa; and the third alfalfa harvest in step S4 is carried out during the flowering stage of yellow alfalfa.

[0016] Step S2 specifically involves: 1) When the initial flowering period of alfalfa overlaps with the heading period of wheat, the flowers of alfalfa attract natural enemies to migrate to the field ridges or farm roads where alfalfa is located. 2) When the wheat is in the jointing and heading stage, the alfalfa that has already flowered is harvested for the first time. At the same time, the harvested alfalfa is beaten to encourage the natural enemies in the alfalfa to transfer from the storage plant system to the farmland, thereby controlling the pests in the farmland. Harvesting wheat encourages the natural enemies to transfer to the alfalfa.

[0017] 3) Prepare for the transfer of natural enemies in wheat fields after wheat harvest. When cutting alfalfa for the first time, leave a stubble height of 5-7 cm (approximately 6 cm). This serves two purposes: firstly, to prevent open spaces on the field ridges that could encourage weed growth; and secondly, to promote rapid growth of new alfalfa shoots, preparing the field for the transfer of natural enemies after wheat harvest. After the first cut, apply topdressing to the storage plant system to promote alfalfa growth.

[0018] 4) After wheat harvesting, the plant reserve system continues to conserve the natural enemies of wheat aphids generated from wheat planting; when the farmland is subsequently plowed, the plant reserve system continues to conserve the natural enemies of wheat aphids; when weeding the farmland, a classified weeding method is used to prevent alfalfa from being affected by herbicides.

[0019] Step S3 specifically involves: By controlling the rice sowing time and aligning the second flowering period of alfalfa with the tillering period of rice, the alfalfa is in its second flowering stage while the rice is in its early tillering stage. This allows for a second harvest, reducing pests on the alfalfa and encouraging natural enemies on the alfalfa to migrate to the farmland. This increases the number of natural enemies in the early stages of the crop, promotes the establishment of natural enemy populations in the early stages, and controls rice planthoppers that migrate in early on, thereby reducing the base population of rice planthoppers throughout the entire growth period.

[0020] Step S4 specifically involves: When the alfalfa reaches its third flowering stage, which overlaps with the rice heading stage, the plant reserve system re-cultivates a new batch of natural enemies. When the alfalfa's third flowering stage overlaps with the rice jointing and heading stage, the third harvest is carried out to transfer the natural enemies from the alfalfa to the farmland, providing a natural enemy pool for the farmland in the middle and late stages of rice growth and controlling the main pest, the rice planthopper.

[0021] The natural enemies mentioned are one or more combinations of predatory and parasitic natural enemies. The predatory natural enemies are one or more combinations of spiders, ladybugs, hoverflies, horseflies, and ground beetles. The parasitic natural enemies are mainly composed of parasitic wasps, which are one or more combinations of black egg wasps, braconid wasps, and taeniaceae.

[0022] In step S2, 2), the alfalfa is harvested for the first time before and during the heading stage of wheat, which prompts the natural enemy storage plant system to transfer to the farmland and promotes the natural enemies to prey on pests.

[0023] The specific operation for harvesting alfalfa is as follows: the alfalfa is cut manually or mechanically, and the cutting speed is controlled at 10 meters per minute; the cutting direction is from the side of the alfalfa planting area away from the farmland to the side of the alfalfa planting area closer to the farmland; the cutting time is chosen during the peak activity period of natural enemies, between 8-10 am or 4-6 pm; immediately after cutting, the cut alfalfa is beaten 3-5 times, and the cut alfalfa is piled up at the edge of the field to dry for 2-4 hours, which encourages natural enemies to move from the cut alfalfa to the farmland.

[0024] The transfer of natural enemies to alfalfa after wheat harvesting specifically involves: after the wheat harvest is completed and the wheat straw is obtained, the wheat straw is piled up at the edge of the field to dry and beat, which encourages more natural enemies to transfer to the storage plant system.

[0025] Step S2, 4) specifically refers to: 4.1) Harvest wheat while alfalfa continues to protect natural enemies; start harvesting from the part of the field ridges away from where alfalfa is planted to encourage natural enemies to move to the alfalfa on the ridges; 4.2) Plow the farmland, and the alfalfa continues to conserve and protect the natural enemies that have migrated from the farmland to the alfalfa planting area due to plowing; after irrigating, plowing and leveling the field, plant rice; 4.3) When weeding farmland, use a classified weeding method to prevent alfalfa from being affected by herbicides.

[0026] In step 4.3), the classified weed control method specifically involves dividing the farmland into transplanted and direct-seeded fields. For transplanted fields, before transplanting, 80-100 grams of 35% benzyl butachlor is applied per mu for pre-emergence weed control, followed by timely machine transplanting. Seven days after machine transplanting, 80-100 grams of 35% benzyl butachlor mixed with 25 kg of urea is applied per mu. The farmland is kept at a water level of 3-5 cm for 5 days. For direct-seeded fields, 10 herbicide balls containing 80-100 ml of 60% isoxaflutole butachlor are applied per mu. After the water has naturally dried for 2 days, rice can be directly sown.

[0027] The alfalfa planting method is as follows: the alfalfa is planted in a subtropical rainy environment. Before planting the alfalfa, the alfalfa planting area is leveled, the farm roads are cleared, weeds are removed but no herbicides are sprayed, the field ridges are raised, and stones with a diameter greater than 5cm are removed from the alfalfa planting area. For soil with a water volume content higher than 10%, stones with a diameter less than 5cm are scattered in to artificially increase the permeability of the soil in the alfalfa planting area, that is, the permeability of the field ridges or farm roads.

[0028] The beneficial effects of this invention are: 1. This invention innovatively constructs a year-round cycle system for natural enemies in rice paddies. By introducing new storage plants in southern rice-growing areas and constructing a storage plant complex, it provides a special solution for alfalfa cultivation in subtropical rice-wheat rotation and high-temperature, high-humidity environments. It establishes a complete year-round cycle system for natural enemies in southern rice paddies, creating a two-way transfer channel of "storage plant → farmland → storage plant," achieving peak-shaving and valley-filling of natural enemy density throughout the year. This ensures a continuous year-round cycle of natural enemies for rice paddy pests, enhancing the natural control effect of natural enemies in the early stages and enabling the complete elimination of chemical pesticides for controlling rice planthoppers in the field, resulting in significant economic and ecological benefits.

[0029] 2. The concept and method of the natural enemy year-round cycle system practiced in this invention can establish a complete year-round cycle system for paddy fields under subtropical rice-wheat or rice-rapeseed double cropping systems, spanning the continuous cycle of wheat-rice two-season crops, solving the problem of interruption of natural enemy conservation under crop rotation system, breaking the co-occurrence effect of pests and natural enemies in conventional rice production, and solving the ultimate problem in the field of natural enemy conservation that natural enemies always develop alongside pests.

[0030] 3. This invention forcibly transfers natural enemies through active intervention methods such as timing of harvesting and beating. By precisely aligning with the key growth stages of crops through three harvests, it provides natural enemies in a targeted and timely manner. By increasing the number of natural enemies in rice fields before the tillering stage and before the main generation of brown planthoppers, it is the first in China to construct a year-round natural enemy cyclical transfer system to conserve natural enemies, increase the number of natural enemy populations, enhance the natural control capacity of rice fields, reduce the control pressure of the main generation of brown planthoppers, and solve the ultimate problem of few natural enemies and slow population establishment in rice fields in the early stage. Attached Figure Description

[0031] Figure 1 A schematic diagram illustrating the annual cycle of natural enemies in southern rice paddies using perennial leguminous plants; Figure 2 The number of predators in the ground traps of the four treatments on May 21, the day of wheat harvest (A) and May 22, one day after wheat harvest (B); Figure 3 A table showing the number of predatory natural enemies (excluding water frogs) in a single ground trap on alfalfa field ridges and conventional weed field ridges after rice transplanting; Figure 4 The population changes of Braconid bee natural enemies in a two-way Markov net during the entire wheat harvesting process; Figure 5 A graph showing the net emigration of natural enemies of the ground beetle family in two-way ground traps before and after rice harvest; Figure 6 A graph showing the change in the number of parasitic natural enemies in a two-way Marshall net during the key growth stages of rice; Figure 7 A graph showing the change in the number of parasitic natural enemies in a bidirectional Marshall net before and after rice harvest; Figure 8 The net emigration value of ground-based predators of the ground beetle family in two-way ground traps before and after rice harvest. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Plant alfalfa at the designated sowing time along paddy field ridges, farm roads, or in non-agricultural habitats other than ridges and farm roads. Alfalfa, together with native functional weeds in the alfalfa planting area, forms a multi-enemy reserve plant system, namely a small-scale natural enemy reservoir (perennial alfalfa) - corridor (alfalfa and functional weeds) - rice (wheat). Pests are generated in the paddy fields from wheat or rice planting, which in turn cultivates natural enemies of the pests. Adjusting the flowering period of alfalfa to match the key growth period of wheat or rice planted in the paddy fields allows natural enemies to be transferred and conserved between the paddy fields and the reserve plant system.

[0034] Technical characteristics of the annual cycle transfer system for natural enemies in southern rice paddies: Storage of the plant storage system – conservation – transfer 1 to crop 1 – utilization of crop 1 – transfer 2 to the plant storage system – storage – conservation – transfer 3 to crop 2 – utilization of crop 2 – transfer to the plant storage system (back to the beginning).

[0035] like Figure 1 As shown, the specific methods for crop natural enemy transfer and conservation are as follows: S1. Arrange the sowing time of alfalfa. Plant alfalfa and let it grow together with local functional weeds to build a storage plant system of multiple natural enemies. This will match the flowering period of alfalfa with the key growth period of wheat or rice planted in paddy fields to protect natural enemies. S2. The first flowering period of alfalfa overlaps with the heading period of wheat. The flowers of alfalfa attract natural enemies to crawl into the storage plant system, thereby protecting the natural enemies. When wheat is in the jointing and heading stage, the first harvest of alfalfa prompts the natural enemies protected in the storage plant system to transfer to the paddy field, thereby controlling paddy field pests. When wheat is harvested, the growth of alfalfa allows the storage plant system to take over the natural enemies in the paddy field after wheat harvest and protect the natural enemies. S3. Control the sowing time of rice in the field so that the second flowering period of alfalfa or the first flowering period of yellow alfalfa overlaps with the tillering period of rice. Carry out the second harvest of purple alfalfa or yellow alfalfa to encourage the transfer of natural enemies on purple alfalfa or yellow alfalfa to rice fields, provide a natural enemy pool for rice fields in the middle and late stages of rice growth, and promote the establishment of natural enemy populations in rice fields in the early stage. S4. When the third flowering period of alfalfa or the second flowering period of yellow alfalfa overlaps with the heading period of rice, the third harvest is carried out to encourage the transfer of newly generated natural enemies on alfalfa or yellow alfalfa to the paddy field, providing a natural enemy pool for the paddy field in the later stage of rice growth and controlling the main pest, rice planthopper.

[0036] The alfalfa varieties are heat-resistant, moisture-resistant, and have a high autumn dormancy level. Generally, one or a combination of two of WL525, Algonquin, and Triple Play can be selected for alfalfa planting. The yellow alfalfa to be planted is large-leaved yellow alfalfa. Local functional weeds include one or a combination of Zoysia japonica, Imperata cylindrica, Setaria viridis, Cynodon dactylon, Alopecurus aequalis, and Alopecurus aequalis, among others. These local functional weeds themselves have some parasitic natural enemies. The key growth periods for wheat are the jointing and booting stages and the heading stage, while the key growth periods for rice are the tillering and booting stages.

[0037] Each flowering period of alfalfa consists of two phases: the initial flowering phase and the peak flowering phase. The first harvest of alfalfa in step S2 is carried out during the initial flowering phase; the second harvest of alfalfa in step S3 is carried out during the initial flowering phase; and the third harvest of alfalfa in step S4 is carried out during the flowering period. In other words, harvesting can be carried out at either the initial flowering phase or the peak flowering phase.

[0038] The first harvest of alfalfa is during the wheat heading stage, used as a pollution-free vegetable; the second harvest is during the early tillering stage of rice, used as feed for Hu sheep; and the third harvest is during the rice heading stage, used as feed for Hu sheep.

[0039] When the alfalfa is yellow alfalfa, a differentiated harvesting and utilization strategy shall be implemented: S2: The first harvest of alfalfa is carried out 35-40 days after sowing and used as a pollution-free vegetable. At the same time, it also encourages some natural enemies to transfer to wheat fields. S3: The second harvest of alfalfa is carried out at the initial flowering stage (corresponding to the early tillering stage of rice) to serve as feed for sheep and encourage natural enemies to migrate to rice paddies; S4: The alfalfa is harvested for the third time during its second flowering stage (corresponding to the rice heading stage) to serve as feed for the lake sheep and to provide a reservoir of natural enemies for the later stages of rice growth. The differentiation strategy achieves the dual benefits of natural enemy conservation and economic crop / feed production.

[0040] Step S1 involves arranging the sowing time for alfalfa. Specifically, for the first year of sowing, spring sowing is scheduled after the Awakening of Insects (Jingzhe) and alfalfa is broadcast on paddy field ridges, farm roads, or non-agricultural habitats. Autumn sowing is scheduled after rice harvest and during winter wheat sowing, with alfalfa broadcast on paddy field ridges, farm roads, or non-agricultural habitats. Specifically, from early October to early November, after the rice harvest, alfalfa is sown simultaneously with winter wheat in the paddy field, planting it on the surrounding open spaces, specifically on the ridges and slopes of the paddy field where the winter wheat is located. This ensures that the initial flowering period of alfalfa overlaps with the heading period of wheat.

[0041] Step S2 is as follows: 1) When the initial flowering period of alfalfa overlaps with the heading period of wheat, the flowers of alfalfa attract natural enemies to crawl towards the field ridges or farm roads where alfalfa is located. In other words, alfalfa provides nutrition for natural enemies such as hoverflies, black egg wasps and parasitic wasps; alfalfa also has an attraction effect on black egg wasps.

[0042] 2) When wheat is in the jointing and booting stage (late March to mid-April in northern Zhejiang, and shifted to other areas), carry out the first harvest of flowering alfalfa. At the same time, beat the harvested alfalfa to encourage the natural enemies of wheat aphids in alfalfa to transfer from the storage plant system to the paddy field, thereby controlling pests in the paddy field. That is, the natural enemies of wheat aphids are transferred by harvesting wheat and alfalfa.

[0043] 3) Prepare for the transfer of natural enemies of aphids in the wheat field after wheat harvest: When cutting alfalfa for the first time, leave a stubble height of 5-7 cm, or about 6 cm. This is to prevent the creation of empty spaces on the field ridges that could attract weeds to sprout, and to promote the rapid growth of new alfalfa shoots, thus preparing for the transfer of natural enemies in the paddy field after wheat harvest. After the first cut, apply topdressing to the storage plant system, i.e., the area where alfalfa was planted, to promote alfalfa growth.

[0044] 4) Alfalfa natural enemy relay station carries out the transfer of natural enemies after wheat harvest: After wheat is harvested, the storage plant system continues to conserve natural enemies of wheat aphids; when the paddy field is plowed, the storage plant system continues to conserve natural enemies of wheat aphids; when weeding the paddy field, the classified weeding method is used to prevent alfalfa from being affected by herbicides.

[0045] Step S3 specifically involves the overlap of the second flowering period of alfalfa with the tillering period of rice. By controlling the rice sowing time, the second flowering period of alfalfa is made to overlap with the tillering period of rice, providing a reservoir of natural enemies for rice in the early stage of rice growth and controlling pests that migrate in early on. When alfalfa is in its second flowering period (late June to mid-July), rice is in the early tillering stage. The second harvest is carried out to reduce pests on alfalfa and encourage predatory and parasitic natural enemies such as spiders and ladybugs on alfalfa to transfer to rice fields, promoting the establishment of natural enemy populations in rice fields in the early stage, controlling pests that migrate in early on, and reducing the base number of pests throughout the year.

[0046] Step S3 specifically involves the overlap of the third flowering period of alfalfa with the heading stage of rice. When alfalfa reaches its third flowering stage, which overlaps with the rice heading stage, the plant reserve system can re-cultivate a new batch of natural enemies. The timing of the third alfalfa harvest should be controlled when the third flowering stage of alfalfa is close to or overlaps with the rice jointing and heading stage. This will encourage the transfer of natural enemies from alfalfa to the rice field, improve the control of natural enemies in the rice field, provide a natural enemy pool for the rice field in the middle and late stages of rice growth, and control the main pest, the rice planthopper.

[0047] Natural enemies are one or more combinations of predatory and parasitic natural enemies. Predatory natural enemies include one or more combinations of spiders, ladybugs, hoverflies, horseflies, and ground beetles. Parasitic natural enemies are mainly composed of parasitic wasps, which include one or more combinations of black egg wasps, braconid wasps, and taeniaceae. Pests are mainly composed of wheat aphids and rice planthoppers.

[0048] In step S2, 2), harvesting wheat and alfalfa to transfer natural enemies specifically involves harvesting alfalfa for the first time before wheat heads emerge and during the heading stage, thereby prompting the natural enemy storage plant system to transfer to the paddy field and encouraging natural enemies to feed on pests.

[0049] The specific operation for harvesting alfalfa is as follows: the alfalfa is cut manually or mechanically, and the cutting speed is controlled at 10 meters per minute; the cutting direction is from the side of the alfalfa planting area away from the farmland to the side of the alfalfa planting area closer to the farmland; the cutting time is chosen during the peak activity period of natural enemies, between 8-10 am or 4-6 pm; immediately after cutting, the cut alfalfa is beaten 3-5 times, and the cut alfalfa is piled up at the edge of the field to dry for 2-4 hours, which encourages natural enemies to move from the cut alfalfa to the farmland.

[0050] After wheat harvesting, the transfer of natural enemies to alfalfa specifically involves: after the wheat harvest is completed, the collected wheat straw is piled up at the edge of the field to dry, prompting more natural enemies to transfer to the storage plant system.

[0051] Step S2, section 4) specifically refers to the role of alfalfa natural enemy relay stations in facilitating the transfer of natural enemies after wheat harvest: 4.1) Harvest wheat while alfalfa continues to protect natural enemies; start harvesting from the part of the field ridges away from the alfalfa planted to encourage natural enemies to move to the alfalfa on the ridges.

[0052] 4.2) Plow the paddy field, and continue to protect the natural enemies of alfalfa that have migrated from the paddy field to the alfalfa planting area due to plowing; after irrigating, plowing and leveling the field, plant rice; 4.3) When weeding rice paddies, a classified weeding method is used to prevent alfalfa from being affected by herbicides. Currently, drones are used for large-scale spraying of pesticides, and general methods are used for application. Inevitably, the nectar plants planted on the field ridges will be affected. This method will not affect the nectar plants on the field ridges.

[0053] In step 4.3), the specific method of classified weeding is as follows: the paddy field is divided into transplanted paddy field and direct-seeded paddy field. For transplanted paddy field, when the paddy field is leveled, before transplanting, apply 80-100 grams of 35% benzyl butyl per mu for sealing, and then carry out machine transplanting at the appropriate time. Seven days after machine transplanting, that is, after the seedlings have survived, apply 80-100 grams of 35% benzyl butyl per mu mixed with 25 kg of urea. The paddy field is kept at a water level of 3-5 cm for 5 days. For direct-seeded rice paddies, when leveling the paddy field, apply 80-100 ml of a pesticide solution containing 60% isoxaflutole•butachlor using spray balls, averaging 10 spray balls per acre. After the water has naturally dried for 2 days, rice can be directly sown. This avoids the impact on alfalfa during weeding. Currently, with large-scale spraying by drones, conventional methods of application inevitably affect nectar-producing plants on the field ridges. This method provides good weed control without affecting nectar-producing plants on the field ridges.

[0054] Alfalfa thrives in subtropical, rainy, hot, and humid environments. Before planting, the planting area should be leveled, farm roads cleared, and weeds removed (but without herbicides). The paddy field ridges should be raised, and stones larger than 5cm in diameter removed. For soil with a moisture content exceeding 10%, pebbles smaller than 5cm in diameter should be added to artificially increase the permeability of the ridges or farm roads, adapting to the rainy and humid climate of southern regions. Alfalfa is primarily planted on farm roads. If planted on small ridges, the ridge height should be increased. When the soil moisture content exceeds 10%, pebbles or sand should be added, and drainage channels should be dug at the lower points of the ridges to reduce humidity in the alfalfa seed area.

[0055] By aligning the growth period of alfalfa with the important growth periods of rice (wheat), a year-round natural enemy cycle system is constructed. This system consists of natural enemies of the previous season's crop - alfalfa (a natural enemy transfer bridge during seasonal transition) - the next season's crop. Specifically, alfalfa is sown in autumn or spring. When the initial flowering period of alfalfa overlaps with the jointing and booting period of wheat, the initial flowering period of alfalfa's second flowering coincides with the early tillering stage of rice after transplanting, and the third flowering period coincides with the jointing and booting period of rice. This promotes the transfer of predatory and parasitic natural enemies such as spiders between crops and alfalfa, thereby achieving the goal of controlling pests.

[0056] The natural enemy annual cycle transfer system includes, but is not limited to, storage plant systems, storage plant utilization systems (lake sheep, honey), storage plant cultivation methods in subtropical high-humidity areas, and storage plant protection systems (avoiding herbicide damage). Specific implementation includes the following aspects: I. Constructing a plant reserve system with multiple natural enemies Alfalfa is planted on the ridges of rice paddies, farm roads, or open spaces around farmland in southern regions. Alfalfa is sown together with winter wheat, and after the rice harvest, it is planted on the ridges and slopes of the rice paddies.

[0057] A multi-enemy storage plant system: using alfalfa + local functional weeds as the storage plant complex, a small-scale natural enemy reservoir (perennial alfalfa) - corridor (alfalfa and field weeds) - rice (wheat) is constructed.

[0058] Methods for cultivating alfalfa under subtropical, rainy conditions. The specific planting steps are as follows: 1. When planting wheat, plant alfalfa on the field ridges; from early October to early November.

[0059] 2. Level the area where alfalfa will be planted, and remove weeds from the area, but do not spray herbicides; raise the ridges in the middle of the paddy field to at least 30cm above the bottom of the paddy field, and widen the ridges to 70-80cm.

[0060] 3. Apply base fertilizer: Apply 100 kg of superphosphate per mu before plowing.

[0061] 4. Till the alfalfa planting area, i.e., the field ridges or shallow tillage roads: Remove stones with a diameter greater than 5cm. For soils with a high degree of clay content, scatter stones with a diameter less than 5cm to artificially increase the permeability of the field ridges or tillage roads to adapt to the rainy and humid climate of the south.

[0062] 5. Alfalfa variety selection: Choose heat-resistant, moisture-resistant, and high-dormant varieties, such as WL525 and Algonquin.

[0063] 6. The sowing rate for naked sowing is 1.5 kg / mu.

[0064] 7. Seed coating: Using coating material, the planted alfalfa seeds and the coating material are coated at a mass ratio of 1:1 to obtain coated alfalfa seeds.

[0065] 8. Inoculate with alfalfa rhizobia. When sowing in land where alfalfa has never been grown before, inoculate coated alfalfa seeds with alfalfa rhizobia to obtain inoculated alfalfa rhizobia seeds. Sow these seeds. For inoculation, use 5 grams of inoculum per kilogram of seeds, prepare a bacterial solution, sprinkle it on the seeds, mix thoroughly, and sow immediately after mixing. If no inoculum is available, mix the seeds with soil from an old alfalfa field at a minimum ratio of 1:1, meaning the soil mass must be greater than or equal to the seed mass. Inoculated alfalfa seeds must be sown promptly.

[0066] 9. Sun-dry the seeds for 2-3 days before sowing to break dormancy and improve germination rate and seedling uniformity.

[0067] 10. Sowing method: Row sowing or broadcast sowing. Rows should be 25 cm wide and 10 cm apart. Generally, 2-3 rows are sown along the field ridges. Row sowing should be done on the side of the farm road closest to the paddy field. When broadcasting, shallow tillage should be carried out before sowing. Alfalfa can be sown alone or mixed with perennial ryegrass. When mixing, the two types of seeds can be mixed before sowing, or alfalfa can be sown in rows first, and then perennial ryegrass can be broadcast between the two rows of alfalfa.

[0068] For row sowing, each alfalfa row is 25cm wide, with a spacing of 10cm between each row. Generally, 2-3 rows of alfalfa are sown on each field ridge, with the direction of the alfalfa rows parallel to the direction of the field ridges. For machine-cultivated roads, alfalfa is sown in rows on the side closest to the paddy field, with the direction of the alfalfa rows parallel to the edge of the paddy field. For broadcast sowing, shallow tillage is performed before broadcasting. Alfalfa can be sown alone or mixed with perennial ryegrass seeds. For mixed sowing, the mass ratio of alfalfa seeds to perennial ryegrass seeds is 2:1 before sowing. Alternatively, alfalfa can be sown in rows first, followed by broadcasting perennial ryegrass seeds between the two alfalfa rows.

[0069] II. Constructing a yearly cycle system of natural enemies Appropriately arrange the sowing period and adjust it so that the flowering period of alfalfa matches the key growth period of wheat or rice, and construct a year-round natural enemy cycle system.

[0070] (a) For the first time, the flowering period of alfalfa overlapped with the jointing-heading period of wheat. 11. To overlap alfalfa flowering with wheat heading: In the first year of sowing, spring sowing should be scheduled after the Awakening of Insects (Jingzhe) and broadcast immediately; autumn sowing should be scheduled after rice harvest and during winter wheat sowing, with alfalfa broadcasted along paddy field ridges or farm roads. This will allow the initial flowering period of alfalfa to overlap with the heading period of wheat.

[0071] 12. When the flowering period of alfalfa overlaps with that of wheat heading, the flowers of alfalfa provide nutrition for hoverflies, black egg wasps, and parasitic wasps; alfalfa also attracts black egg wasps.

[0072] 13. First harvest of alfalfa to encourage the transfer of natural enemies from alfalfa to farmland: Harvest alfalfa when it has flowered and wheat is in the jointing and heading stage (late March to mid-April in northern Zhejiang, shifting to other areas). Simultaneously, beat the harvested alfalfa to encourage natural enemies such as spiders, ladybugs, hoverflies, and parasitic wasps to migrate from the alfalfa along field ridges or farm roads to the wheat field, controlling aphids in the wheat. After harvesting, pile the alfalfa at the edge of the field to dry, helping spiders, ladybugs, and parasitic wasps migrate to the main field. Harvest alfalfa for the first time before and during wheat heading to encourage natural enemies to migrate from alfalfa to the wheat field, promoting their feeding on wheat aphids and other pests.

[0073] 14. Prepare for the transfer of natural enemies such as field spiders and ladybugs after wheat harvest: Leave a stubble height of about 6 cm after the first cut. This serves two purposes: firstly, to prevent open spaces on the field ridges from attracting weeds, and secondly, to promote the rapid growth of new alfalfa shoots, preparing for the transfer of natural enemies such as field spiders after wheat harvest. Apply appropriate topdressing after the first cut to promote alfalfa growth.

[0074] (ii) For the first time, alfalfa natural enemy relay stations served as a means for the transfer of natural enemies after wheat harvest. 15. Harvest wheat while alfalfa continues to protect natural enemies in the wheat field. Start harvesting from the part of the field away from the alfalfa-planted ridges to encourage spider predators to migrate to the alfalfa ridges.

[0075] 16. Till the farmland, and use alfalfa to continue protecting spider predators that have migrated from the farmland due to tilling. After irrigating, tilling, and leveling the fields, plant rice.

[0076] 17. When weeding rice paddies, a new method is used to prevent alfalfa from being affected by herbicides (currently, large-scale spraying by drones and general application methods inevitably affect nectar-producing plants planted on the paddy ridges; this method will not affect nectar-producing plants on the ridges). For transplanted rice paddies, apply 80-100 grams of 35% benzyl butachlor mixed with urea per mu (667 square meters) 7 days after machine transplanting (after the seedlings have established themselves), and maintain a 3-5 cm water layer in the field for 5 days; for direct-seeded rice paddies, when leveling the paddy field, apply 80-100 ml of 60% isoxaflutole butachlor (using herbicide pellets) (an average of 10 pellets per mu), and after the water has naturally dried for 2 days, begin direct-seeding rice; this avoids the impact of weeding on alfalfa.

[0077] (ii) Second overlap: The second flowering period of alfalfa overlaps with the tillering period of rice, providing a natural enemy pool for rice fields in the early stage of rice growth and controlling pests that migrate in during the early stage.

[0078] 18. Control the timing of the second alfalfa harvest: During the second flowering period of alfalfa (late June to mid-July), when rice is in the early tillering stage, the second harvest should be carried out. This will reduce pests on alfalfa and encourage predatory and parasitic natural enemies such as spiders and ladybugs on alfalfa to migrate to the rice field, thus promoting the establishment of natural enemy populations in the rice field in the early stage and controlling pests that migrate in early on.

[0079] (iii) Third overlap: The third flowering period of alfalfa overlaps with the heading period of rice, providing a natural enemy pool for rice fields in the middle and late stages of rice growth and controlling the rice planthopper, the main pest generation.

[0080] 19. Control the timing of the third harvest of alfalfa. When the third flowering period of alfalfa is close to or overlaps with the jointing and booting period of rice, carry out the third harvest to encourage natural enemies to transfer from alfalfa to rice fields and improve the control of natural enemies in rice fields.

[0081] III. Saving Plants - Downstream High-Value Application System 20. Alfalfa is fed to sheep in combination with wheat and rice straw. Taking into account the protection of natural enemies of rice and the high biomass of alfalfa, the optimal harvest time ensures good overall benefits. The first harvest of alfalfa is at the initial flowering stage; the second harvest is at the initial flowering stage; and the third harvest is at the flowering stage.

[0082] 21. Alfalfa is fed in combination with Chinese honeybees to produce alfalfa honey.

[0083] 22. Yellow alfalfa, also known as golden flower vegetable or yellow flower grass head, can be used as a green and pollution-free vegetable in addition to protecting natural enemies. It can be harvested 35 days after sowing to promote the transfer of natural enemies.

[0084] IV. Coordinate pesticide safety for both plant storage systems and emergency control, ensuring compatibility of plant storage systems with other control methods. 23. When using herbicides in rice paddies or wheat fields, avoid or minimize the impact on alfalfa. When weeding rice paddies, adopt new methods to prevent alfalfa from being affected by herbicides (currently, large-scale spraying by drones and conventional methods inevitably affect nectar-producing plants planted on the field ridges; this method has good weed control and will not affect nectar-producing plants on the ridges). For transplanted rice paddies, apply 80-100 grams of 35% benzyl butachlor mixed with urea per mu (approximately 0.067 hectares) 7 days after machine transplanting (after the seedlings have established themselves), maintaining a 3-5 cm water layer in the field for 5 days. For direct-seeded rice paddies, when leveling the paddy field, apply 80-100 ml of 60% isoxaflutole butachlor (using spray balls) (an average of 10 spray balls per mu). After the water has naturally dried for 2 days, begin direct-seeding rice. This avoids the impact of weeding on alfalfa.

[0085] 24. For emergency control of pesticides in paddy fields, start applying the pesticides from the edge of the field away from alfalfa to encourage natural enemies to move from the paddy field to alfalfa.

[0086] like Figure 2 As shown, the main predators in the two-way ground traps were ground spiders and horseflies. On May 22, the day after the first harvest, the number of predatory predators migrating from the wheat field to the alfalfa ridge was significantly higher than the number migrating from the wheat field to the weed ridge. F (1, 6) = 9.800 P =0.02), where the significance difference analysis was based on the Tukey method of multiple comparisons, and different letters on the bars represent significant differences at the P < 0.05 level.

[0087] like Figure 3As shown, on July 3, the number of predatory enemies in the alfalfa field ridges reached a peak of 3.4±0.4, which was higher than the 1.8±1.11 in the weed field ridges on the same day, and significantly higher than the 0.8±0.37 predatory enemies in the alfalfa field ridges on July 29 (F(1,8)=22.533, P=0.0014). In the following months, the number of predatory enemies in the alfalfa field ridges remained low until the harvest in November, when the number of predatory enemies increased to 2.67±0.33. The number of predatory enemies on November 13 was significantly higher than that on October 22 (F(1,6)=30.964, P=0.0015). This indicates that when rice is first transplanted, there are many predatory natural enemies in the alfalfa field ridges, and they have the potential to provide ground natural enemies for the rice field. They gradually migrate into the rice field until the rice is harvested. The alfalfa field ridges can serve as a sanctuary for natural enemies, prompting the ground natural enemies in the rice field to return to the vicinity of the field ridges.

[0088] like Figure 4 As shown, the main parasitic wasp groups in the annual enemy cycle system include black egg wasps, braconid wasps, and tassel wasps. The peak number of parasitic natural enemies occurred on May 19th, the peak number of black egg wasps occurred on May 24th, the peak number of braconid wasps occurred on May 18th, and the peak number of tassel wasps occurred on May 19th. Furthermore, on May 23rd, it was observed that the number of black egg wasps migrating from alfalfa field ridges to wheat fields was significantly higher than the number migrating from weed field ridges to wheat fields, indicating that alfalfa has an attractive effect on black egg wasps. On May 23, the number of braconid wasps migrating from wheat fields to alfalfa field ridges and from alfalfa to wheat fields was significantly higher than that migrating from wheat fields to weed field ridges and from weed field ridges to wheat fields. On May 24, the number of braconid wasps migrating from wheat fields to alfalfa field ridges was also significantly higher than that in the other three treatments. This indicates that alfalfa field ridges have a strong attraction for braconid wasps, and that the attraction to natural enemies is time-dependent.

[0089] like Figure 5 As shown, the net migration value of natural enemies of the family Aegilops along the edges of alfalfa fields before harvest was the highest among the four groups, significantly higher than the net migration value along the edges of alfalfa fields after harvest (F(1,22)=4.468, P=0.046), while the net migration value along the edges of alfalfa fields after harvest was the lowest.

[0090] During the wheat harvest, alfalfa demonstrated a time-dependent attraction to both predatory and parasitic natural enemies. During another rice harvest, alfalfa also exhibited a good attraction and retention effect on ground-based predatory natural enemies. Spiders remained the primary predatory natural enemy in ground traps. On the first day after the first harvest, the number of predatory natural enemies migrating from wheat fields to alfalfa ridges was significantly higher than the number migrating from wheat fields to weed ridges, indicating that alfalfa has an attractive effect on predatory natural enemies.

[0091] like Figure 6 As shown, this further verifies that the top three parasitic wasps in the annual cycle system of natural enemies, ranked from highest to lowest number, are black egg wasps, braconid wasps, and tassel wasps; on the second day after the first harvest, alfalfa on the field ridges has a significant attraction effect on parasitic natural enemies; on the second and third days after the first harvest, alfalfa on the field ridges has a significant attraction effect on braconid wasps, and the attraction effect is time-dependent.

[0092] like Figure 7 and Figure 8 As shown, at the beginning of rice transplanting, the dense alfalfa on the paddy field ridges, resembling a "fence," can store natural enemies migrating during wheat harvest. The alfalfa contains a large number of natural enemies, providing them for the rice paddies after transplanting. After rice transplanting, natural enemies gradually migrate into the paddy fields, and by harvest time, the "fence"-like alfalfa ridges can still protect them, encouraging ground-based natural enemies to return to the vicinity of the ridges. Furthermore, actual observations during the experimental period from May to November showed that the alfalfa grew well, effectively protecting natural enemies. In the two-way ground trap, on November 13th, the day of rice harvest, the number of predatory natural enemies migrating from the paddy field to the alfalfa ridges was significantly higher than the number migrating from the alfalfa ridges to the paddy field and from the paddy field to the grass ridges. This also verifies the feasibility of using perennial leguminous plants to construct a year-round natural enemy cycle system in southern rice paddies.

[0093] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for the conservation and transfer of natural enemies using a perennial leguminous plant-based system for the year-round cyclical transfer of natural enemies in southern rice paddies, characterized in that... Alfalfa is planted at appropriate sowing times along paddy field ridges, farm roads, or in non-agricultural habitats other than ridges and farm roads. The alfalfa, together with native functional weeds in the alfalfa planting area, forms a storage plant system for various natural enemies. This storage plant system stores and conserves natural enemies of pests. The alfalfa flowering period is adjusted to match the critical growth period for paddy field pest control. By actively cutting the storage plant system, the natural enemy population is artificially encouraged to move to the farmland. When the crops planted in the farmland are harvested, the natural enemies migrate out of the farmland and into the storage plant system, thus enabling the natural enemies to move and conserve between the farmland and the storage plant system.

2. The method for the conservation and transfer of natural enemies using a perennial leguminous plant-based year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 1, is characterized in that... The specific methods for the transfer and conservation of crop natural enemies are as follows: S1. Arrange an appropriate sowing period to plant alfalfa. The alfalfa grows together with the native functional weeds in the alfalfa planting area to construct a storage plant system of multiple natural enemies, so that the flowering period of alfalfa matches the key growth period of wheat or rice planted in the farmland for the purpose of conservation and transfer of natural enemies. S2. The first flowering period of alfalfa overlaps with the jointing and heading period of wheat. When wheat is heading, alfalfa is harvested for the first time to encourage the natural enemies protected in the storage plant system to transfer to the farmland and thus control pests in the farmland. The alfalfa continues to grow until wheat is harvested, so that the storage plant system can take over the natural enemies that migrate out of the farmland after wheat is harvested and protect the natural enemies. S3. Control the sowing time of rice in the field so that the second flowering period of alfalfa is before the tillering period of rice. Carry out the second harvest of alfalfa to encourage the transfer of natural enemies on alfalfa to rice fields, provide a natural enemy pool for the middle and late stages of rice growth, and promote the establishment of natural enemy populations in rice fields in the early stage. S4. When the third flowering period of alfalfa overlaps with the heading period of rice, the third harvest is carried out to encourage the transfer of newly generated natural enemies from alfalfa to the paddy field, providing a natural enemy pool for the paddy field in the later stage of rice growth and controlling the main pest, rice planthopper.

3. The method for the conservation and transfer of natural enemies using a perennial leguminous plant-based year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 2, is characterized in that... The farmland is a southern paddy field; the alfalfa is one or more of alfalfa purple and alfalfa yellow; the alfalfa purple is one or more of WL525, Algonquin, and Tribulus terrestris; the alfalfa yellow is large-leaved alfalfa; the native functional weeds are one or more of zoysia grass, cogongrass, foxtail grass, bermudagrass, barnyardgrass, and purslane; the key growth periods of wheat are the jointing and booting stage and the heading stage, and the key growth periods of rice are the tillering stage and the booting stage. Each flowering period of the alfalfa is divided into two stages: the initial flowering stage and the full flowering stage. When the alfalfa is purple alfalfa, the first cutting of alfalfa in step S2 is carried out during the initial flowering stage of purple alfalfa; the second cutting of alfalfa in step S3 is carried out during the initial flowering stage of purple alfalfa; and the third cutting of alfalfa in step S4 is carried out during the flowering stage of alfalfa. When the alfalfa is yellow alfalfa, the first alfalfa harvest in step S2 is carried out 35-40 days after sowing; the second alfalfa harvest in step S3 is carried out during the initial flowering stage of yellow alfalfa; and the third alfalfa harvest in step S4 is carried out during the flowering stage of yellow alfalfa.

4. The method for the conservation and transfer of natural enemies using a perennial leguminous plant-based year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 2, is characterized in that... In step S1, the appropriate sowing time for planting alfalfa is arranged as follows: In the first year of sowing, the spring sowing time is arranged after the Awakening of Insects, and alfalfa is broadcast on the ridges of rice paddies, farm roads, or non-agricultural habitats; the autumn sowing time is after the rice harvest and when winter wheat is sown, and alfalfa is broadcast on the ridges of rice paddies, farm roads, or non-agricultural habitats.

5. The method for the conservation and transfer of natural enemies using a perennial leguminous plant-based year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 2, is characterized in that... Step S2 specifically involves: 1) During the wheat heading stage, the alfalfa that has already flowered is harvested for the first time. At the same time, the harvested alfalfa is beaten to encourage the natural enemies in the alfalfa to transfer from the storage plant system to the farmland, thereby controlling the pests in the farmland. The natural enemies are transferred to the alfalfa by harvesting wheat. 2) When cutting alfalfa for the first time, the stubble height should be 5-7 cm to prepare for natural enemies in the field after wheat harvest; after the first cut, the storage plant system should be fertilized to promote alfalfa growth. 3) After wheat harvest, the plant reserve system continues to conserve the natural enemies of the early-stage agricultural pests caused by wheat planting; when the farmland is subsequently plowed, the plant reserve system continues to conserve the natural enemies of agricultural pests; when weeding the paddy fields, a classified weeding method is used to prevent alfalfa from being affected by herbicides.

6. The method for the conservation and transfer of natural enemies using a perennial leguminous plant-based year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 2, is characterized in that... Step S3 specifically involves: Controlling the rice sowing time to overlap the second flowering period of alfalfa with the tillering period of rice: When alfalfa is in its second flowering period, rice is in the early tillering stage. Carrying out the second harvest reduces pests on alfalfa and encourages natural enemies on alfalfa to transfer to rice fields, increasing the number of natural enemies in the early stage of rice fields, promoting the establishment of natural enemy populations in the early stage of rice fields, and controlling rice planthoppers that migrate in the early stage, thereby reducing the base number of rice planthoppers throughout the entire growth period. Step S4 specifically involves: When the alfalfa reaches its third flowering stage, which overlaps with the rice heading stage, the plant reserve system re-cultivates a new batch of natural enemies. When the alfalfa's third flowering stage overlaps with the rice jointing and heading stage, the third harvest is carried out to transfer the natural enemies from the alfalfa to the rice field, providing a natural enemy reservoir for the rice field in the middle and late stages of rice growth, thereby controlling rice planthoppers.

7. A method for the conservation and transfer of natural enemies using a perennial leguminous plant-based year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 2, is characterized in that... The natural enemies mentioned are one or more combinations of predatory and parasitic natural enemies. The predatory natural enemies are one or more combinations of spiders, ladybugs, hoverflies, horseflies, and ground beetles. The parasitic natural enemies are mainly composed of parasitic wasps, which are one or more combinations of black egg wasps, braconid wasps, and taeniaceae.

8. A method for the conservation and transfer of natural enemies using a perennial leguminous plant-based year-round cyclical transfer system for natural enemies in southern rice paddies, as described in claim 5, is characterized in that... In step S2, 1), the alfalfa is harvested for the first time before the wheat heads begin to emerge, which prompts the natural enemy storage plant system to transfer to the paddy field and encourages the natural enemies to feed on pests. The specific operation for harvesting alfalfa is as follows: the alfalfa is cut manually or mechanically, and the cutting speed is controlled at 10 meters per minute; the cutting direction is from the side of the alfalfa planting area away from the farmland to the side of the alfalfa planting area closer to the farmland; the cutting time is chosen during the peak activity period of natural enemies, between 8-10 am or 4-6 pm; immediately after cutting, the cut alfalfa is beaten 3-5 times, and the cut alfalfa is piled up at the edge of the field to dry for 2-4 hours, which encourages natural enemies to move from the cut alfalfa to the farmland; The specific method of transferring natural enemies to alfalfa after wheat harvest is as follows: After the wheat harvest is completed and the wheat straw is obtained, the wheat straw is piled up at the edge of the field to dry and beat, which encourages more natural enemies to transfer to the storage plant system. Specifically, step S2, 3) is as follows: 3.1) Harvest wheat while alfalfa continues to protect natural enemies; start harvesting from the part of the field ridges away from where alfalfa is planted to encourage natural enemies to move to the alfalfa on the ridges; 3.2) After tilling the farmland, alfalfa continues to conserve and protect natural enemies that have migrated from the farmland to the alfalfa planting area due to tilling; after irrigating, tilling and leveling the field, rice is planted. 3.3) When weeding rice paddies, use a classified weeding method to prevent alfalfa from being affected by herbicides.

9. The natural enemy conservation and transfer system for constructing a year-round cyclical transfer system for natural enemies in southern rice paddies using perennial leguminous plants, as described in claim 8, is characterized in that... In step 3.3), the classified weed control method is as follows: the paddy field is divided into transplanted paddy field and direct-seeded paddy field. For transplanted paddy field, before transplanting, 80-100 grams of 35% benzyl butachlor is applied per mu and then machine transplanting is carried out. Seven days after machine transplanting, 80-100 grams of 35% benzyl butachlor mixed with 25 kg of urea is applied per mu. The paddy field is kept at a water level of 3-5 cm for 5 days. For direct-seeded paddy field, 80-100 ml of 60% isoxaflutole butachlor solution balls are applied. Ten solution balls are applied per mu. After the water has naturally dried up for 2 days, rice can be directly sown.

10. A method for the conservation and transfer of natural enemies using a perennial leguminous plant-based annual cycle transfer system for natural enemies in southern rice paddies, as described in claim 2, is characterized in that... The alfalfa planting method is as follows: the alfalfa is planted in a subtropical rainy environment. Before planting the alfalfa, the alfalfa planting area is leveled and the weeds are removed, but no herbicides are sprayed. The paddy field ridges in the alfalfa planting area are raised, and stones with a diameter greater than 5 cm in the alfalfa planting area are removed. For soils with a water volume content higher than 10% in the alfalfa planting area, stones with a diameter less than 5 cm are scattered in to artificially increase the permeability of the soil in the alfalfa planting area.

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