Carrier plant system for preventing and controlling vegetable thrips and application of carrier plant system

Abstract

The invention relates to the technical field of agricultural pest prevention and control, in particular to a carrier plant system for preventing and controlling vegetable thrips and application of the carrier plant system. The invention constructs a carrier plant system of orius similis for preventing and controlling vegetable thrips, the carrier plant is wheat, the substitute food is wheat aphid, and the beneficial organism is orius similis. The carrier plant system provided by the invention continuously maintains the population quantity of orius similis in greenhouse vegetable crops, prolongs the action time of orius similis, effectively improves the biological control efficiency of pests such as thrips on target crops, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of agricultural pest control technology, and in particular to a carrier plant system for controlling thrips in vegetables and its application. Background Technology

[0002] Thrips are significant pests of various vegetable crops, including those in the Solanaceae, Leguminosae, and Cucurbitaceae families. Varieties include western flower thrips, flower thrips, melon thrips, bean thrips, and tobacco thrips. They cause substantial economic losses to crops through direct feeding and indirect virus transmission. Vegetable thrips (western flower thrips, flower thrips, melon thrips, and bean thrips) are listed as Class A crop pests. Southern small flower bug (Symplocos spp.) Orius strigicollis The Southern Flower Bug (Small Flower Bug) is an important predatory natural enemy insect widely distributed in agricultural ecosystems. It is highly effective at preying on various small agricultural pests such as thrips, aphids, and whiteflies, and possesses efficient predation and search capabilities as well as a low diapause rate, making it a highly valuable natural enemy. Currently, significant progress has been made in the artificial breeding of the Southern Flower Bug, leading to its commercial production and application. It is widely used for the biological control of pests such as thrips and whiteflies in greenhouse vegetables, orchards, ornamental plants, and greenhouse agriculture.

[0003] However, the primary method of releasing southern flower bugs currently is broadcasting, directly scattering adult and nymphal bugs mixed with sawdust onto crops, requiring multiple re-releases. This method can damage the southern flower bugs and is susceptible to interference from water droplets, air currents, and agricultural operations, hindering their colonization and effectiveness, and significantly increasing the cost of biological control. Therefore, there is an urgent need to develop a safe and sustainable field release technology for southern flower bugs to reduce the number of releases, improve colonization efficiency, and extend the duration of action.

[0004] Carrier plant systems represent a novel approach to the rearing and release of natural enemies. This open-ended system comprises three basic elements: carrier plants, alternative food sources, and beneficial organisms. Carrier plants are typically non-target crops used to rear alternative hosts or prey, providing habitat and food for beneficial organisms. Alternative food sources, i.e., alternative hosts or prey, are generally herbivorous arthropods that do not harm the target crop. This system enables the large-scale rearing of natural enemies while providing food and habitat for released natural enemies, promoting the establishment of stable populations and playing a crucial role in achieving efficient and sustained pest control.

[0005] Carrier plant systems are widely used in the biological control of greenhouse pests, but there is currently very little research on carrier plant systems for *Symplocos serratus* and their application in thrips control in vegetables. Only a broad bean-bean aphid-*Symplocos serratus* carrier plant system has been reported for use in tea gardens to control tea thrips. However, since bean aphids damage leguminous vegetables, this system cannot be used for thrips control in vegetables. Summary of the Invention

[0006] To address the aforementioned technical challenges, this invention provides a carrier plant system for thrips control in vegetables, comprising a carrier plant, a substitute food, and a beneficial organism; the carrier plant is wheat, the substitute food is wheat aphid, and the beneficial organism is southern small flower bug.

[0007] Through extensive screening of carrier plants and alternative foods, this invention ultimately discovered that when wheat is selected as the carrier plant and wheat aphids are selected as the alternative food, the carrier plant system constructed with the southern flower bug does not harm the target crop and can sustainably maintain the population of the southern flower bug, prolonging the duration of the southern flower bug's effect and effectively achieving the goal of thrips control in vegetables.

[0008] Preferably, the wheat aphid is the wheat bifida.

[0009] In specific implementation, the thrips include at least one of the following: western flower thrips, flower thrips, melon thrips, bean thrips, and tobacco thrips.

[0010] In practice, the vegetables mentioned include at least one of the following: solanaceous vegetables, legumes, and cucurbitaceous vegetables.

[0011] In specific implementation, the solanaceous vegetables include at least one of the following: capsicum (preferably chili), solanum, tobacco, and wolfberry.

[0012] In specific implementation, the legume vegetables include at least one of the following: common bean, pea, cowpea, soybean, lentil, broad bean, alfalfa, and lupin.

[0013] In the specific implementation process, the Cucurbitaceae vegetables include at least one of the following: Cucurbita, Pumpkin, Watermelon, Winter Melon, Loofah, Bitter Melon, Chayote, and Trichosanthes.

[0014] In the specific implementation process, the inoculation ratio of wheat aphid and southern small flower bug in the carrier plant system is (35~45):2; preferably 40:2.

[0015] This invention also found that when the proportion of wheat aphids in the carrier plant system is too low, the population propagation of *Symplocos spp.* in the system cannot be maintained; when the proportion of wheat aphids is too high, it leads to an overabundance of aphids, a rapid population explosion, and serious damage to the carrier plant, which is detrimental to the maintenance of the carrier plant system. Choosing the above inoculation ratio effectively achieves the stable propagation of *Symplocos spp.* in southern China without causing serious damage to the carrier plant.

[0016] Furthermore, this invention provides the application of the aforementioned carrier plant system in the control of thrips in vegetables.

[0017] More specifically, the present invention provides a method for controlling vegetable thrips, including using the aforementioned carrier plant system for control.

[0018] Preferably, after the vegetables are transplanted, the carrier plant system is released preventively, with one carrier plant system released per 75-85 square meters. When thrips appear on the vegetables, the release density is increased to one carrier plant system per 35-45 square meters.

[0019] Preferably, after increasing the release density, the product is released once every two weeks, for a total of 3 to 4 releases.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention constructs a carrier plant system for the control of the southern flower bug (Thrips spp.) in vegetables. The carrier plant is wheat, the substitute food is wheat aphids, and the beneficial organism is the southern flower bug. This carrier plant system sustainably maintains the population size of the southern flower bug in greenhouse vegetable crops, prolongs its effective period, and effectively improves the biocontrol efficiency of thrips and other pests on target crops, demonstrating broad application prospects. Attached Figure Description

[0021] Figure 1 This describes the egg-laying situation of the Southern Flower Bug on different crops.

[0022] Figure 2 This is the result of selective aphid production by adult wheat aphids on chili peppers and wheat.

[0023] Figure 3 The results show the predation rate of adult Southern Flower Bugs on third-instar nymphs of the wheat aphid.

[0024] Figure 4 It refers to the aphid population size in the plant system with different inoculation ratios.

[0025] Figure 5 The population size of *Smallflower Bug* in different inoculation ratios is recorded in the plant system.

[0026] Figure 6 This is the result of the influence of the carrier plant system on the field population of small flower bugs.

[0027] Figure 7 This is the result of the influence of the carrier plant system on the field thrips population. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. In the embodiments provided in this specification, where specific techniques or conditions are not specified, they are performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0029] Example 1: Screening of Southern Small Flowering Bug Carrier Plants for Thrips Control in Vegetables Carrier plants are the most important element in the carrier plant system. The following factors need to be considered when selecting carrier plants: (1) Carrier plants are generally non-target cultivated crops that can be used to feed alternative prey or hosts, providing habitats, oviposition sites and food for beneficial organisms; (2) They do not share pests with cultivated crops and will not introduce pests to cultivated crops; (3) Carrier plants are easy to plant, grow quickly, and can be planted in large quantities in a short period of time.

[0030] To screen for carrier plants that can be used in vegetable crops and support the population of Southern Flower Bug, we selected two easy-to-grow and fast-growing non-target crops (corn and wheat). Taking the target crop, pepper, as an example, we compared the Southern Flower Bug's oviposition selection on the target crop and the two gramineous crops (corn and wheat) to screen for carrier plants that can provide oviposition sites for the Southern Flower Bug.

[0031] An oviposition selection experiment was conducted using insect rearing cages. Corn, wheat, and peppers were randomly placed in 30×30×30cm insect rearing cages, and five pairs of male and female Southern Flower Bugs (3 days old) were released into each cage to lay eggs. After 3 days, the male and female Southern Flower Bugs were removed, and the corn, wheat, and peppers were placed in separate insect rearing cages. After the Southern Flower Bug eggs hatched, the number of eggs laid on different plants was recorded. Each treatment was repeated five times.

[0032] The egg-laying situation of the southern small flower bug on three kinds of plants (corn, wheat, and pepper) is shown in [the original text]. Figure 1 The results showed that the southern flower bug laid the most eggs on the target crop, pepper, with an average of 22.6 eggs per plant; followed by wheat, with an average of 3.4 eggs per plant; and the fewest eggs were laid on corn, with an average of 0.8 eggs per plant. Therefore, compared to corn, wheat can provide a better oviposition site for the southern flower bug, and thus wheat was chosen as the carrier plant.

[0033] Example 2: Alternative Food Screening The selection of alternative food sources is also crucial when constructing a carrier plant system. Alternative food sources are generally phytophagous insects on the carrier plant that share common natural enemies with the target pest and typically do not harm the cultivated crop. In this example, the wheat aphid (using the wheat aphid as an example) was selected as an alternative prey to verify whether it harms the target crop, pepper.

[0034] This study evaluated the growth, development, and reproduction of the wheat aphid on the target crop, pepper, and the carrier plant, wheat. Pepper and wheat leaves were placed in 6cm diameter petri dishes (the base of the leaves was wrapped with damp cotton to retain moisture). One newly hatched first-instar aphid was placed in each dish, and the edges of the dishes were sealed with sealing film. The dishes were then placed in an artificial climate chamber (temperature 26±1℃, photoperiod L14:D10, relative humidity 60%). The survival and developmental stages of the nymphs were observed and recorded every 12 hours.

[0035] Table 1 shows the developmental period and population growth parameters of the wheat aphid on chili peppers and wheat. The results indicate that the wheat aphid can complete its growth and development on wheat, but it is difficult to survive on chili peppers.

[0036] Table 1. Developmental duration (days) of the alternative food aphid, *Aphis oryzae*, on the target crop, pepper, and the carrier plant, wheat.

[0037] Next, the selectivity of adult wheat aphids for producing aphids on the target crop pepper and the carrier plant wheat was determined.

[0038] Chili leaves, wheat leaves (with the base wrapped in damp cotton to retain moisture), and 20 adult wheat aphids were placed in 15×30 cm insect rearing boxes, with each treatment repeated 6 times. The treated insect rearing boxes were placed in an artificial climate chamber, and the number of aphids laid on wheat and chili leaves was checked and recorded after 24 hours.

[0039] The selective aphid production of adult wheat aphids on wheat and chili peppers is shown in the figure. Figure 2 The results showed that adult wheat aphids laid the most aphids on wheat, with an average of 12 aphids per day; they did not lay eggs on chili peppers. In conclusion, the wheat aphid does not harm the target crop, chili peppers, and as an alternative food source, it will not introduce new pests to the target crop.

[0040] Example 3: Predation rate of adult Southern Small Flower Bugs on Wheat Aphids To further verify that the selected alternative food (prey) could feed the southern flower bug, we measured the predation rate of the southern flower bug on the wheat aphid.

[0041] One-day-old Southern Flower Bug adults were placed individually in 6cm diameter petri dishes, with 1.5cm segments of kidney beans added for moisture. The Southern Flower Bugs were starved for 24 hours before being used as natural enemies. 10, 20, and 30 third-instar nymphs of the wheat aphid per dish, along with one of the natural enemies, were introduced into each dish. The edges of the petri dishes were sealed with Parafilm, and the treated dishes were placed in an artificial climate chamber. Each treatment was repeated 20 times. The number of viable wheat aphids was recorded after 24 hours.

[0042] The predation rate of adult Southern Flower Bugs on third-instar nymphs of the wheat aphid is shown in [reference needed]. Figure 3 The results showed that the predation rate of adult *Symplocos septemlobus* on third-instar nymphs of the wheat aphid increased with increasing prey density. At a prey density of 10 nymphs / plate, both male and female adults of *Symplocos septemlobus* had equal predation capacity, with a predation rate of 10 nymphs / day. At a prey density of 20 nymphs / plate, female adults of *Symplocos septemlobus* showed the strongest predation capacity, with an average predation rate of 18.6 nymphs / day, followed by male adults with an average predation rate of 17.6 nymphs / day. At a prey density of 30 nymphs / plate, female adults of *Symplocos septemlobus* showed the strongest predation capacity, with an average predation rate of 26 nymphs / day, followed by male adults with an average predation rate of 25.5 nymphs / day.

[0043] This shows that the Southern Flower Bug has a strong predatory ability against the wheat aphid and can be used for the rearing of the Southern Flower Bug.

[0044] Example 4: The effect of the carrier plant system on the population propagation of *Symplocos septemlobus*. To determine the optimal inoculation ratio of wheat aphid / southern small flower bug, we measured the effects of five inoculation ratios (wheat aphid / southern small flower bug 10:2, 20:2, 30:2, 40:2, and 50:2), namely, the aphid / small flower bug ratios of 10:2, 20:2, 30:2, 40:2, and 50:2, on the population expansion and maintenance of southern small flower bugs.

[0045] When the wheat seedlings grew to about 10-15cm, each pot of seedlings was inoculated with 10, 20, 30, 40, or 50 aphids. Then, two mated female Southern Flower Bugs (3-5 days old) were introduced. The five treatments were placed in separate 30×30×30cm insect rearing cages. The number of aphids on the wheat seedlings and the number of Southern Flower Bugs were observed and recorded daily for a total of 17 days. Each treatment was repeated four times.

[0046] The research results are as follows: Figure 4 and Figure 5The results showed that when the inoculation ratio of *Aphidius oryzae* to *Smallflower floridulus* was 10:2, the aphids in the carrier plant system were completely preyed upon by the *Smallflower floridulus* by day 9, and all the *Smallflower floridulus* died by day 10, making it impossible to maintain the *Smallflower floridulus* population in the system. When the inoculation ratio was 20:2, the number of aphids in the carrier plant system gradually decreased, and all aphids were preyed upon by day 17, while the *Smallflower floridulus* population did not increase by day 17. When the inoculation ratios were 30:2 and 40:2, the number of aphids in the carrier plant system remained stable throughout the 17-day observation period. However, at the 30:2 ratio, the *Smallflower floridulus* population increased more slowly over time, while at the 40:2 ratio, the population gradually increased over time, demonstrating that this release density effectively achieved stable propagation of *Smallflower floridulus*. When the inoculation ratio of wheat aphid / southern small flower bug is 50:2, although the population of southern small flower bug shows an increasing trend, the population of aphids explodes rapidly due to the overabundance of aphids, causing serious damage to the carrier plant and hindering the maintenance of the carrier plant system.

[0047] In summary, a wheat aphid / southern flower bug inoculation ratio of 40:2 is the optimal release ratio, which can maintain a stable wheat-wheat aphid-southern flower bug carrier plant system. Based on the above results, this invention establishes a wheat-wheat aphid-southern flower bug carrier plant system. Potted wheat seedlings 10-20cm tall are used as carrier plants. Wheat aphids / southern flower bugs are inoculated into the carrier plants at a ratio of 40:2. There are 200 potted wheat seedlings, 400 wheat aphids, and 20 flower bugs.

[0048] Example 5: Effects of a carrier plant system on the population dynamics of *Symplocos serratus* and *Thrips* in the field. To clarify the impact of the wheat-wheat aphid-southern small flower bug carrier plant system on the population dynamics of southern small flower bugs and thrips in the field, we conducted a field release experiment of the wheat-wheat aphid-southern small flower bug carrier plant system.

[0049] The experiment was conducted in spring in a chili pepper greenhouse at the Yangdu Research Base of the Zhejiang Academy of Agricultural Sciences in Haining City, Zhejiang Province. Two treatments were set up: a control and a carrier plant system. In the carrier plant system treatment, after the chili peppers were transplanted, the carrier plant system was placed in the greenhouse for preventative release, with a release density of 5 carrier plant systems per greenhouse (400 square meters). When thrips appeared on the chili peppers (2-3 thrips / flower), the release density was increased to 10 carrier plant systems. During release, the carrier plant systems were evenly placed next to the chili pepper crops, and release was repeated every 2 weeks for a total of 3-4 times.

[0050] The population dynamics of southern flower bugs and thrips in the field were investigated from the time the peppers were planted. A five-point sampling method was used, with 10 flowers randomly sampled at each point. The number of flower bugs and thrips in each flower was recorded. The survey was conducted every two weeks for the entire growing season (approximately 6 months).

[0051] See field population dynamics of Southern Flower Bug and Thrips Figure 6 and Figure 7 The results showed that, compared with the control greenhouse, the population of *Symplocos spp.* in the greenhouse with the carrier plant system increased and could be maintained for at least 6 months. Figure 6 ), and can effectively suppress thrips populations in the field ( Figure 7 ).

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carrier plant system for thrips control in vegetables, comprising a carrier plant, alternative foods, and beneficial organisms; characterized in that, The carrier plant is wheat, the alternative food is wheat aphid, and the beneficial organism is southern small flower bug.

2. The carrier plant system according to claim 1, characterized in that, The wheat aphid mentioned is the wheat bifida aphid.

3. The carrier plant system according to claim 1 or 2, characterized in that, The thrips include at least one of the following: western flower thrips, flower thrips, melon thrips, bean thrips, and tobacco thrips.

4. The carrier plant system according to claim 1 or 2, characterized in that, The vegetables include at least one of the following: Solanaceae vegetables, Leguminosae vegetables, and Cucurbitaceae vegetables.

5. The carrier plant system according to claim 4, characterized in that, The Solanaceae vegetables include at least one of the following: Capsicum, Solanum, Tobacco, and Lycium. And / or, the legumes include at least one of the following: common bean, pea, cowpea, soybean, lentil, broad bean, alfalfa, and lupin. And / or, the Cucurbitaceae vegetables include at least one of the following: Cucurbita, Cucurbita, Watermelon, Winter Melon, Loofah, Bitter Melon, Chayote, and Trichosanthes.

6. The carrier plant system according to claim 1, characterized in that, In the aforementioned carrier plant system, the inoculation ratio of wheat aphid and southern small flower bug is (35~45):

2.

7. The application of the carrier plant system according to any one of claims 1 to 6 in the control of thrips in vegetables.

8. A method for controlling thrips in vegetables, characterized in that, This includes using the vector plant system according to any one of claims 1 to 6 for control.

9. The prevention and control method according to claim 8, characterized in that, After the vegetables are transplanted, the carrier plant system according to any one of claims 1 to 6 is released preventively, with one carrier plant system released per 75 to 85 square meters. When thrips appear on the vegetables, the release density is increased to one carrier plant system per 35 to 45 square meters.

10. The prevention and control method according to claim 9, characterized in that, After increasing the release density, release once every 2 weeks, for a total of 3 to 4 releases.

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