Application of broccoli intercropping wheat in conservation of natural enemies of wheat pests

Abstract

The invention relates to the technical field of crop planting, in particular to application of broccoli intercropping wheat in conservation of natural enemies of wheat pests. The invention provides application of broccoli intercropping wheat in conservation of natural enemies of wheat pests. The broccoli and wheat intercropping can significantly improve the number and diversity of natural enemies in the field, and has the function of conserving the natural enemies. The main natural enemies of aphidius gifuensis and Ephilosophila melanogaster have significant response to the intercropping mode, which indicates that the intercropping system is helpful for enhancing the biological prevention and control effect on pests such as wheat aphids and the like.

Description

Technical Field

[0001] The invention relates to the technical field of crop planting, and in particular to application of broccoli intercropped with wheat in conserving natural enemies of wheat pests. Background Art

[0002] Ecological control was first proposed by Ma Shijun (1979), and later extended to pest ecological regulation by Ge Feng (2020). It is a strategy for pest management. It is based on the principles of "prevention first, ecological priority, integrated governance, and precise policy implementation", emphasizing that the two processes of regulation and control complement each other. Starting from the interaction between "crops-pests-natural enemies and their surrounding environment" in the farmland landscape ecosystem, it fully considers the biological pest control function, pollination function and decomposition function of insects. On the basis of giving full play to the pest control of natural enemies, the resistance of crops and creating an environment that is unfavorable to pests but favorable to the growth of natural enemies and crops, it integrates ecological control technology, agricultural control, biological control, physical and chemical control, modern biotechnology and reasonable chemical control, and constructs an "economic, simple and effective" ecological technology system to control pests below the ecological and economic threshold level, so as to achieve the goals of economic feasibility, ecological sustainability and social acceptability. The biological control of natural enemies is mainly achieved through predation and parasitism (Baker et al., 2020). In terms of predation, the earliest successful case of large-scale biological control in history was the introduction of Australian ladybugs (Rodolia cardinalis) in California in 1888 to control cottony scale (Icerya purchasi) (Flint et al., 1981). Recent studies have shown that a variety of small flower bugs have significant control effects on thrips, such as the control of western flower thrips by the East Asian small flower bug (Orius sauteri) (Zhu Zhengyang et al., 2022) and the predation of southern small flower bugs (O. similis) on western flower thrips and yellow thrips (Mo Lifeng et al., 2013; Sun Ying et al., 2021). In terms of parasitism, trichogrammatids are one of the most successfully used egg parasitoids, which can parasitize the eggs of more than 1,270 species of insects from 90 families and have been widely used in the prevention and control of crop pests such as corn, rice, and vegetables (Wang et al., 2014; Zang et al., 2021).

[0003] Functional plants are currently a hot topic in research, as they can increase the number of natural enemies in target fields by conserving natural enemies of pests. Studies have shown that planting sesame on ridges can significantly increase the number of parasitic natural enemies in rice fields (Zhu Pingyang, 2012). Janet et al. (2023) found that intercropping corn with functional plants such as Chenopodium album and Bidens pilosa can increase the number of predatory natural enemies by about 10% and increase the abundance of natural enemy species. These results show that functional plants have important potential in increasing the population of natural enemies and strengthening biological control. Wheat is an important food crop in my country, and its safe production is of great significance to ensuring food security (Yan Jia et al., 2020). Pests such as wheat aphids and mites can cause a 30% to 60% reduction in wheat production (Tang Pinghua et al., 2013). At present, the development of moderately large-scale agriculture and the improvement of high-standard farmland have led to a significant reduction in non-crop habitats such as ridges, and the routine use of herbicides has further aggravated the monotony of vegetation in wheat field habitats. Studies have shown that ridge vegetation, as a biological corridor, can provide important support for the biodiversity of natural enemies in wheat fields. Therefore, improving plant diversity in wheat fields is expected to enhance its biological pest control potential by affecting the diversity and richness of natural enemies.

[0004] Cruciferous crops such as broccoli are economic crops commonly grown in winter and spring in southern China, and their planting seasons overlap with winter and spring wheat. However, there is still a lack of systematic research on the effects of intercropping cruciferous crops with wheat on natural enemy communities. Summary of the invention

[0005] In order to solve the above problems, the present invention provides the application of broccoli intercropped with wheat in the conservation of natural enemies of wheat pests. Through the investigation and analysis of arthropod communities in broccoli-wheat intercropped fields and wheat monocropped fields, the present invention aims to: (1) explore the impact of broccoli intercropping on the diversity of natural enemy communities in wheat fields; (2) evaluate the response of major natural enemy species to intercropping patterns; (3) analyze the application potential of broccoli as a functional plant in the biological control of wheat pests. The research results will provide a theoretical basis for the construction of an ecological control system for wheat fields based on functional plants.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The invention provides application of broccoli intercropped with wheat in conserving natural enemies of wheat pests.

[0008] Preferably, the natural enemies of pests include Hymenoptera, Diptera, Coleoptera and spiders.

[0009] Preferably, the Hymenoptera insects include one or more of the following: Myrmecophaga sphenops, Aphidida fasciata and Lycopodiella fasciata.

[0010] Preferably, the Diptera insects include the black-banded syrphid fly.

[0011] Preferably, the Coleopteran insects include six-striped ladybirds and / or oligochaetes.

[0012] Preferably, the spider includes the insectivorous grooved-knotted spider and / or the eight-maculated ball-bellied spider.

[0013] The present invention also provides the use of broccoli intercropped with wheat in reducing the number of Schizaphis graminis.

[0014] Preferably, the method of intercropping broccoli with wheat includes: wheat is sown in rows with a row spacing of 30 cm; 2 rows of broccoli are planted every 20 m of wheat, with a row spacing of 50 cm.

[0015] Preferably, the plant spacing of the broccoli is 50 cm, and the length of the broccoli field is consistent with the length of the wheat field.

[0016] Beneficial effects of the present invention:

[0017] The present invention used the sweep net method, trap method and Ma's net method to investigate the arthropod populations under two different planting patterns from April to May 2024. DNA barcoding technology was used to identify the species of the samples obtained, and the community structure parameters were analyzed. A total of 25 insect species were captured, belonging to 6 orders, including 12 natural enemy species and 13 pest species. In the broccoli-wheat intercropped field, the number of arthropod individuals (539.88±16.70) and the Shannon diversity index (2.37±0.03) were significantly higher than those in the wheat monocropped field (345.61±8.33 and 1.89±0.29, respectively, p<0.05). The number of the main natural enemies, Aphidiusgifuensis and Episyrphus balteatus, was significantly higher in the intercropped field than in the monocropped field (increased by 94.4% and 151.0%, respectively, p<0.01). Intercropping broccoli with wheat can significantly increase the number and diversity of natural enemies in the field, and has the function of conserving natural enemies. The main natural enemies, Aphididae tobacco and Aphididae black-banded, responded significantly to this intercropping pattern, indicating that this intercropping system helps to enhance the biological control effect of pests such as wheat aphids. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0019] Figure 1 Field cropping pattern for intercropping broccoli and wheat

[0020] Figure 2 is the number of main natural enemies under different planting patterns, ** indicates p < 0.01; **** indicates p < 0.0001. DETAILED DESCRIPTION

[0021] The present invention provides the use of broccoli intercropped with wheat in the conservation of natural enemies of wheat pests. In the present invention, the natural enemies of pests preferably include Hymenoptera, Diptera, Coleoptera and spiders. In the present invention, the Hymenoptera preferably includes one or more of the following: Mirror Stem Ichneumonidae, Aphididae and Ridgebranchidae. In the present invention, the Diptera preferably includes Black-banded Syrphid Fly. In the present invention, the Coleoptera preferably includes Six-striped Ladybirds and / or Oligostriated Carabids. In the present invention, the spider preferably includes the Insectivorous Groove-knotted Spider and / or the Eight-spotted Orb-abdomen Spider.

[0022] The present invention also provides the use of broccoli intercropped with wheat in reducing the number of Schizaphis graminis.

[0023] In the present invention, the method of intercropping broccoli with wheat preferably includes: wheat is sown in rows with a row spacing of about 30 cm; 2 rows of broccoli are planted every 20 m of wheat planting, with a row spacing of about 50 cm. The present invention has no special limitation on the varieties of wheat and broccoli. In a specific embodiment of the present invention, the wheat variety is preferably Zhejiang Wheat No. 1, and the broccoli variety is preferably Green Treasure. The present invention has no special limitation on the planting length of wheat. In a specific embodiment of the present invention, the planting length of wheat is 40 m. In the present invention, the spacing between the broccoli is preferably 50 cm, and the length of the broccoli field is consistent with the length of the wheat field. The present invention has no special limitation on the number of repetitions of intercropping wheat and broccoli, and those skilled in the art can make conventional settings.

[0024] In order to further illustrate the present invention, the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0025] Example 1

[0026] 1 Materials and methods

[0027] 1.1 Overview of the test site

[0028] The experiment was conducted from November 2023 to May 2024 at Xingqing Family Farm, Xin'an Avenue, Xin'an Town, Deqing County, Huzhou City, Zhejiang Province (120°18.44'N, 30°57.12'E). The soil type of the experimental site is paddy soil, pH6.5-7.0, and organic matter content is 2.5%. The average temperature during the experiment was 12.5℃, relative humidity was 75%, and annual precipitation was 1200mm.

[0029] The experiment set up six 20m×40m plots, which were randomly assigned to broccoli-wheat intercropping fields (3 plots) ( Figure 1) and wheat monoculture fields (3 plots), with two treatments arranged alternately. Wheat (variety: Zhejiang Wheat No. 1) was sown on November 15, 2023, with a row spacing of 30 cm; broccoli (variety: Green Treasure) was transplanted on December 1, 2023, planted in two rows every 20 m, with a row spacing of 50 cm and a plant spacing of 50 cm. Field management was carried out in accordance with local routine methods, and no pesticides were used during the entire growth period. Irrigation was carried out by furrow irrigation, and fertilization was carried out according to the ratio of N:P:K=1:0.5:0.8 for base fertilizer and topdressing.

[0030] 1.2 Survey Methods

[0031] 1.2.1 Arthropod collection Arthropods were collected from April 1 to May 31, 2024 using the Marsh net method, yellow board method, and trap method. Sampling was conducted every 7 days from 8:00 to 11:00 in clear weather without rain. The specific settings are as follows:

[0032] (1) Mascot net: 200-mesh nylon nets were used, with three placed in each field at intervals of 10 m. The Mascot nets in the broccoli-wheat intercropped field were placed at the junction of broccoli and wheat, with a total of 18 sampling points.

[0033] (2) Yellow board: Use 25 cm × 15 cm yellow insect traps, 10 cm above the top of the crop. The placement is staggered with traps, 3 per field, for a total of 18 sampling points.

[0034] (3) Traps: Plastic cups with a diameter of 9.5 cm (top), 7.0 cm (bottom), and 25.8 cm deep were used, with 50% ethylene glycol solution inside. Three traps were set up in each field, with an interval of 10 m, for a total of 18 sampling points.

[0035] 1.2.2 Sample identification After the collected arthropod samples were fixed with 70% alcohol, they were first identified by morphology, and then the species was confirmed by DNA barcoding technology. DNA was extracted using the modified CTAB method, and the COI gene fragment was amplified using universal primers LCO1490 and HCO2198. The PCR reaction system and procedure are as follows: PCR Mix 10 μL (Bioshark), 0.5 μL of upstream and downstream primers, 1 μL of DNA template, 8 μL of sterile water, 94°C pre-denaturation for 5 min; 94°C denaturation for 30 s, 50°C annealing for 30 s, 72°C extension for 1 min, a total of 35 cycles; 72°C final extension for 10 min (Huang Weidong et al., 2022).

[0036] The sequencing results were compared and identified using NCBI BLAST and molecular systematics methods.

[0037] 1.3 Data processing The following indicators were used to analyze the community structure characteristics:

[0038] (1) Shannon-Wiener diversity index: H = -∑(Pi×lnPi)

[0039] (2) Pielou uniformity index: E = H / lnS

[0040] (3) Simpson's concentration index: C = ∑Pi 2

[0041] Among them, Pi is the ratio of the number of individuals of the i-th species to the total number of individuals in the community, and S is the number of species.

[0042] SPSS 24.0 was used for statistical analysis. One-way ANOVA was used to compare the differences among different treatments. The normality of the data and the homogeneity of variance were verified by Shapiro-Wilk test and Levene test. The LSD method was used for multiple comparisons (α = 0.05). GraphPad Prism 10.1.2 was used to draw graphs.

[0043] 2 Results and analysis

[0044] 2.1 Arthropod community composition

[0045] 2.1.1 Composition of natural enemy species In the survey from April to May 2024, a total of 12 natural enemy insects were obtained, belonging to 4 orders (Table 1). Among them, Coleoptera has the most natural enemies, including Callistoides pericallus, Anoplogenius cyanescens, Menochilus sexmaculata and Harmonia axyridis. Hymenoptera natural enemies include Collyria catoptron, Aleiodes sps. and Aphidius gifuensis, accounting for 23.69% and 20.16% respectively in the two planting modes. In addition, there are also four predatory natural enemies including Episyrphus balteatus of Diptera and Araneae.

[0046] There are 11 natural enemies in both broccoli-wheat intercropping fields and wheat monocropping fields, but the species composition is slightly different: the oligotrophic ground beetle is unique to the intercropping fields, and the pseudo-beetle is unique to the monocropping fields.

[0047] Table 1 Species composition and quantity of natural enemy insects under different planting patterns

[0048]

[0049]

[0050] 2.1.2 Pest species composition During the survey, 13 pest species were found, mainly belonging to Lepidoptera, Coleoptera and Homoptera (Table 2). Lepidoptera and Coleoptera had the most pest species, with 4 and 3 species respectively. Lepidoptera pests included Chilo suppressalis, Plutellaxylostella, Pieris rapae and Macroglossum corythus; Coleoptera pests included Phyllotreta striolata, Phaedon brassicae and Anomala chamaeleon.

[0051] Although there were only three species of Homoptera pests, they were the most numerous, accounting for 19.72% and 29.22% of the total pests in intercropped and monocropped fields, respectively. Among them, Schizaphis graminum was the dominant species, and Myzus persicae was only found in intercropped fields.

[0052] Table 2 Species composition and quantity of pests under different planting patterns

[0053]

[0054] 2.2 Analysis of community structure characteristics

[0055] 2.2.1 Overall community structure The total number of arthropods in broccoli-wheat intercropping fields (539.88±16.70) was significantly higher than that in wheat monocropping fields (345.61±8.33) (F=143.1, p=0.0069). The Shannon-Wiener diversity index in intercropping fields (2.37±0.03) was also significantly higher than that in monocropping fields (1.89±0.29) (F=2.233, p=0.027). There was no significant difference in the Pielou evenness index and Simpson dominance concentration index between the two planting patterns (Table 3).

[0056] Table 3 Farmland community structure parameters under different planting patterns

[0057]

[0058] Different lowercase letters after the data in the same column in the table indicate significant differences at the 0.05 level, the same below.

[0059] 2.2.2 Characteristics of natural enemy communities Analysis of natural enemy communities showed that the total number of natural enemy individuals in intercropping fields (188.67±5.36) was significantly higher than that in monocropping fields (132.67±6.35) (F=3136, p=0.0003). There were no significant differences in the diversity index, evenness index and dominance index of natural enemy communities between the two planting patterns (Table 4).

[0060] Table 4 Parameters of farmland natural enemy community structure under different planting patterns

[0061]

[0062] 2.2.3 Changes in the number of major natural enemies Under the two planting patterns, the tobacco aphid wasp, the insectivorous groove spider (Ummeliatainsecticeps) and the black-banded syrphid fly were all dominant natural enemy species. Among them, the number of tobacco aphid wasp in the intercropping field (103.67±3.93) was significantly higher than that in the monocropping field (53.33±2.60) (p<0.01); the number of black-banded syrphid flies in the intercropping field (42.67±4.63) was also significantly higher than that in the monocropping field (17.00±2.65) (p<0.0001). Although the number of insectivorous groove spiders in the intercropping field (81.33±3.93) was higher than that in the monocropping field (68.00±6.66), the difference was not significant (p>0.05) ( Figure 2 ).

[0063] 3 Discussions

[0064] The present invention found that broccoli-wheat intercropping significantly increased the diversity of arthropods and the number of natural enemies in the field. This is consistent with previous research results on the increase of biodiversity by crop intercropping (Janet et al., 2023). Compared with traditional functional plants such as pickerelweed and mimosa (Xiang et al, 2021; Hei et al, 2022), broccoli has higher practical value as an economic crop. The results of the present invention show that broccoli-wheat intercropping not only provides additional economic benefits, but also enriches the farmland ecosystem by increasing plant diversity. It is particularly noteworthy that the number of tobacco aphid wasps and black-banded aphid flies increased significantly in intercropped fields. This may be attributed to the following aspects: first, broccoli provides additional nectar and pollen resources for these natural enemies, which is conducive to the survival and reproduction of adults; second, peach aphids on broccoli provide alternative hosts or prey for natural enemies, and can still maintain the natural enemy population during periods when wheat aphids occur less frequently; third, the intercropping pattern increases the complexity of plant structure and provides more habitats and refuges for natural enemies. These results support the view that farmland landscape heterogeneity is conducive to the maintenance of natural enemy populations (Ouyang Fang et al., 2016).

[0065] The results of the present invention show that the number of Schizaphis gramineus in monocropping fields is slightly higher than that in intercropping fields, which is similar to the results of previous studies (Xie et al, 2012). However, the significant increase in the number of natural enemies in intercropping fields may have an inhibitory effect on pest populations over a longer time scale. The tobacco aphid wasp has been shown to effectively parasitize Schizaphis gramineus (Song Xiuchao, 2012), and its increase in number in intercropping fields (increased by 94.4%) indicates a stronger potential for biological control. At the same time, the significant increase in the number of black-banded aphid flies (increased by 151.0%) also provides favorable conditions for the biological control of aphids. As an economic crop, broccoli has good ecological and economic benefits when intercropped with wheat. This study confirmed its conservation effect on natural enemies and provided new ideas for building an ecological control system based on functional plants. In practical application, the following aspects need to be done well: (1) select appropriate intercropping density according to local planting habits; (2) combine with other ecological control measures, such as the artificial release of natural enemies; (3) optimize field management measures, such as timely irrigation and fertilization, to create a favorable environment for natural enemies; (4) establish demonstration areas to promote the ecological control model of broccoli-wheat intercropping.

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[0083] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. The application of broccoli intercropping with wheat in conserving natural enemies of wheat pests.

2. The use according to claim 1, characterized in that: The natural enemies of pests include Hymenoptera, Diptera, Coleoptera and spiders.

3. The use according to claim 2, characterized in that: The hymenoptera insects include one or more of the following: mirror stem wasp, tobacco aphid wasp and spiny wasp.

4. The use according to claim 2, characterized in that: The Diptera insects include black-banded hoverfly.

5. The use according to claim 2, characterized in that: The coleopteran insects include six-striped ladybirds and / or oligochaetes.

6. The use according to claim 2, characterized in that: The spiders include the spider Aglaonema spp. and / or the spider Aglaonema spp.

7. Intercropping broccoli with wheat is used to reduce the number of wheat aphids.

8. The use according to claim 1 or 7, characterized in that: The method of intercropping broccoli with wheat includes: wheat is sown in rows with a row spacing of 30 cm; 2 rows of broccoli are planted every 20 m of wheat, with a row spacing of 50 cm.

9. The use according to claim 8, characterized in that: The plant spacing of the broccoli is 50 cm, and the length of the broccoli field is consistent with the length of the wheat field.

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