Use of alpha-pinene in combination with citral in the attraction of spodoptera frugiperda

Abstract

The application discloses application of alpha-pinene and citral in combination in luring Spodoptera frugiperda, and belongs to the technical field of biological control. The application determines habitat selection and oviposition selection preference of Spodoptera frugiperda on different host plants, collects volatiles of nine kinds of host plants preferred by Spodoptera frugiperda by using a dynamic headspace method, and successfully screens out alpha-pinene and citral combination with good luring effect on female and male adult Spodoptera frugiperda by means of GC-MS technology, indoor behavior selection experiment and semi-field verification. Alpha-pinene and citral both belong to natural plant volatiles, and have the characteristics of easy acquisition, low cost, environmental friendliness and the like, and can serve as background materials or combined components of efficient luring agents of Spodoptera frugiperda. The application can effectively promote the construction and improvement of green control technology of Spodoptera frugiperda, and provides a new and effective tool for Spodoptera frugiperda control work.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biological control, and particularly relates to application of alpha-pinene and citral in combination in attracting Spodoptera frugiperda. BACKGROUND

[0002] Spodoptera frugiperda (J E Smith) belongs to Lepidoptera: Noctuidae, and is also known as autumn armyworm. It is one of the major invasive pests in China. The host of Spodoptera frugiperda is wide, and it can feed on more than 80 families and more than 350 species of plants such as corn, sorghum, rice, wheat and peanut. In the field, Spodoptera frugiperda is mainly divided into two types of subpopulations: corn type and rice type. The corn type Spodoptera frugiperda mainly damages corn, sorghum, cotton and other crops, and the rice type Spodoptera frugiperda mainly damages rice and various pastures, which causes serious threat to crop production. Spodoptera frugiperda has strong flying ability and can migrate. It can fly more than 100 km a day with the help of wind, and can fly 18-36 km a day without the help of wind.

[0003] Spodoptera frugiperda is a new type of invasive pest in China, and the state and scientific researchers pay special attention to the control of Spodoptera frugiperda. They are constantly exploring effective control methods for Spodoptera frugiperda. At present, the main method for controlling Spodoptera frugiperda is still the application of chemical pesticides. However, with the long-term and large-scale application of chemical pesticides, their negative effects are becoming more and more significant. On the one hand, environmental pollution caused by pesticide residues is aggravated; on the other hand, pest resistance is gradually formed, and at the same time, a large number of natural enemies and beneficial microorganisms are also killed. According to relevant research, due to the widespread use of chemical pesticides, the tolerance of Spodoptera frugiperda to organophosphorus, carbamate, pyrethroid and other chemical pesticides has been significantly improved, and the problem of resistance has become increasingly prominent. Compared with this, phagostimulant shows significant advantages such as high efficiency, low toxicity, no pollution and no harm to beneficial insects in the application of pest control, and plays a key role in the integrated pest management (IPM) system, which can produce good economic, social and ecological benefits. At present, many scientific researchers recognize the method of attracting pests and monitoring pest occurrence by using insect phagostimulant, and in the field of pest control practice, phagostimulant is considered as one of the efficient methods. The principle of phagostimulant is to take full advantage of the chemical communication mechanism between insects and plants to attract insects with migration characteristics, so as to interfere with the behavior of insects and trap insects, and finally achieve the goal of pest control. It is an efficient, green and environmentally friendly control approach. SUMMARY

[0004] The application aims to provide alpha-pinene and citral as a high-efficiency food attractant background material for Spodoptera frugiperda and application thereof.

[0005] The second object of the application is to provide a composition of a Spodoptera frugiperda food attractant.

[0006] To achieve the above object, the application is implemented by the following technical scheme:

[0007] The application provides application of alpha-pinene and citral composition in attracting Spodoptera frugiperda. The inventors determine the habitat selection and oviposition selection preference of Spodoptera frugiperda on different host plants by field cage test, and determine high-attractive plants such as grass, castor, sudangrass, medium-attractive plants such as chickpea, calendula, and earthchenopodium, and low-attractive host plants such as agastache, syzygium aromaticum, and curcuma. The inventors first collect volatile components of nine different host plants by dynamic headspace method; elute and concentrate the collected volatile component samples, and compare and analyze the components of the samples by GC-MS; compare and obtain components with differences in volatile types and contents among the plants; and finally, through indoor behavior box behavior selection experiment and semi-field trapping experiment, it is determined that alpha-pinene and citral combination has the best attracting effect on Spodoptera frugiperda female and male insects among numerous specific components and different combinations.

[0008] Therefore, the following applications should be within the protection scope of the application:

[0009] Alpha-pinene and citral combination as a Spodoptera frugiperda food attractant background material and application thereof.

[0010] Application of alpha-pinene and citral combination in preparing a Spodoptera frugiperda food attractant.

[0011] Preferably, the composition comprises alpha-pinene, citral and an induction aid selected from one or more of aldehydes with carbon atom number of 6-9 and alcohols with carbon atom number of 6-10.

[0012] Preferably, the induction aid is selected from linalool oxide and phenylacetaldehyde.

[0013] Preferably, the food attractant comprises 40% alpha-pinene, 40% citral, 10% linalool oxide and 10% phenylacetaldehyde by weight percentage.

[0014] Preferably, the amount of alpha-pinene and citral is 10-100 mg / ml, and the amount of linalool oxide and phenylacetaldehyde is 0.1-10 mg / ml.

[0015] Further, the application of the above-mentioned Spodoptera frugiperda attractant composition in attracting Spodoptera frugiperda, or the application in preparing a Spodoptera frugiperda food or attractant should also be within the protection scope of the present application.

[0016] The present application provides the application of an alpha-pinene and citral composition in attracting Spodoptera frugiperda female and male adults, and the present application explicitly the oviposition preference of Spodoptera frugiperda on different host plants, the volatiles of 9 host plants preferred by Spodoptera frugiperda are collected by using a dynamic headspace method, and with the help of GC-MS technology, indoor behavior selection experiment and semi-field verification, an alpha-pinene and citral combination with good attraction effect on Spodoptera frugiperda female and male adults is successfully screened out. Alpha-pinene and citral are both natural plant volatiles, and have the characteristics of easy to obtain, low cost, environmental friendly, etc., and can serve as the background material or combination component of the efficient attractant of Spodoptera frugiperda. The present application can effectively promote the construction and improvement of the green prevention and control technology of Spodoptera frugiperda, and provide a new effective tool for the prevention and control of Spodoptera frugiperda. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a schematic diagram for the habitat selection and oviposition preference test of Spodoptera frugiperda on 20 different host plants. A is a schematic diagram of host plant plot planting, B is a comparison diagram of habitat selection of Spodoptera frugiperda adults on 20 different host plants in the seedling stage, and C is a comparison diagram of the number of egg masses laid by Spodoptera frugiperda adults on 20 different host plants for 7 days.

[0018] Figure 2 It is a GC-MS result diagram of the volatiles of preferred host plants of Spodoptera frugiperda.

[0019] Figure 3 It is a schematic diagram of a three-chamber olfactometer used for behavior selection test, which is designed and manufactured by the Institute of Plant Protection, Chinese Academy of Agricultural Sciences.

[0020] Figure 4 It is the result of the behavior selection test of the volatiles of different preferred host plants on Spodoptera frugiperda. A-H only show the volatiles with attraction effect on Spodoptera frugiperda female and male adults.

[0021] Figure 5 It is the selection rate of Spodoptera frugiperda on different attractant formulations.

[0022] Figure 6The trapping experiments of Spodoptera exigua with different compositions of α-pinene and citral as the base substances. A is the trapping number chart of the combination of α-pinene and citral; B is the trapping number chart of α-pinene and citral as the base substances, supplemented with oxidized linalool and phenylacetaldehyde as the induction adjuvants; C is the comparison chart of the trapping numbers of different combinations; D is the schematic diagram of the trapping test position in the greenhouse; E is the trapping chart of oxidized linalool + phenylacetaldehyde + α-pinene + citral; F is the trapping chart of α-pinene + citral. DETAILED DESCRIPTION

[0023] The specific embodiments of the present application are described below to facilitate the understanding of the present application for those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, as long as various changes are obvious within the spirit and scope of the present application defined and determined by the appended claims, all the inventions utilizing the concept of the present application are within the scope of protection.

[0024] Example 1 Spodoptera exigua habitat selection and oviposition selection test on 20 different host plants

[0025] The test plants include 20 species, including corn Zea mays L., elephant grass Pennisetum purpureum Schum., ryegrass Lolium perenne L., ginger Zingiber officinale Roscoe, sudangrass Sorghum sudanense (Piper) Stapf, Alocasia macrorrhiza (L.) Schott, turmeric Curcuma longa L., onion Allium cepa L., sorghum Sorghum bicolor (L.) Moench, Eleusine indica (L.) Gaertn., Pelargonium hortorum Bailey, Calendula officinalis L., Tagetes erecta L., buckwheat Fagopyrum esculentum Moench., Coriandrum sativum L., Ricinus communis L., Ageratum conyzoides L., Dysphania ambrosioides (L.) Mosyakin & Clemants, chickpea Cicer arietinum L., and Ocimum gratissimum L. Corn was used as a control, and a total of 20 host plants were subjected to behavior selection tests of the fall armyworm in a field cage of 20 m x 20 m x 2.5 m. The 20 plants were randomly distributed and planted in a plot of 2 m x 2 m, with a row spacing of 40 cm and a plant spacing of 20 cm. Ten plants were planted in each row, and five rows were planted in each plot, for a total of 50 plants. The plots were spaced 2 m apart, and a 2-m protective row was set up around the 20 plots. The plants were arranged in a 5 x 4 rectangle, and each field cage was spaced 4 m apart. The specific arrangement is shown in Figure 1 The test was repeated six times, and the test was conducted at all crop stages. Four hundred adult fall armyworms (200 females:200 males) were released into each cage, and the number of fall armyworms, the number of egg masses, and the number of eggs were investigated for 50 host plants in each plot for 7 consecutive days after release.

[0026] Oviposition rate (%) = (number of eggs / total number of eggs) x 100

[0027] Plant attraction level: Oviposition rate < 0.1%, plant attraction level is low attraction; 0.1% < oviposition rate < 10%, plant attraction level is medium attraction; oviposition rate > 10%, plant attraction level is high attraction.

[0028] Results as shown in Figure 1 were found to prefer oviposition on corn, oregano, chickpea, ephedra, ageratum conyzoides, castor, marigold, turmeric, sudangrass, elephant grass, etc.

[0029] Example 2 Collection and identification analysis of nine host plant volatiles of Spodoptera frugiperda

[0030] Plants with vigorous growth and uniform total leaf area were selected from plants grown to the 4-leaf stage. The soil and flowerpots were sealed with tin paper to prevent soil odor from interfering with plant volatiles. Dynamic headspace sampling (DHS) was used to collect volatiles from nine plants, with Poirapak Q as the adsorbent. The collection time was 8 hours, and each plant was repeated three times. The adsorption column of the collected gas was eluted into a sample bottle with 300 μL of n-hexane, and decyl acetate was added as an internal standard at a concentration of 10 ng / μL. Gas chromatography-mass spectrometry (GC-MS) (Shimadu GCMS-QP2020, HB-5 chromatographic column) was used for analysis. The temperature program used was 40°C (1 min), 4°C / min to 130°C (5 min), 10°C / min to 250°C (5 min). The inlet temperature was 250°C, the mode was splitless, and the carrier gas was N2. The inlet flow rate and column flow rate were 10 mL / min and 1 mL / min, respectively. The ionization method was EI 70 eV, the scan range was 50-650 amu, and the scan speed was 2500 amu / s. After analysis, the collected volatiles were identified by comparison with the NIST 17.0 library.

[0031] The results showed that 62 chemical substances were identified in the volatiles of the nine plants, including 22 alkenes, 2 alkanes, 8 aldehydes, 7 ketones, 9 alcohols, 12 esters, and 2 aromatic compounds. Among them, 32 substances were unique to one plant, 1 unique to castor, 2 unique to sudangrass, 5 unique to elephant grass, 2 unique to ephedra, 5 unique to marigold, 3 unique to chickpea, 8 unique to turmeric, 4 unique to ageratum conyzoides, and 2 unique to oregano. See Table 1 and Figure 2 Figure 2 are the gas chromatograms of volatiles from different host plants, and Table 1 shows the unique chemical substances of individual plants.

[0032] Table 1 Unique chemical substances of individual plants​

[0033]

[0034] Screening of C. partell behavioral modulating compounds

[0035] According to the analysis results of the volatile collection of 9 kinds of host plants, 28 kinds of main common compounds and differential compounds in host plant volatiles were selected (Table 2, all purchased from Tokyo Chemical Industry Co., Ltd., Japan) for the attraction and repellent effect test of female and male C. partell. The concentration of test compounds was set to 0.1 mg / mL, 1 mg / mL, 10 mg / mL, 100 mg / mL, and n-hexane was used as a solvent to dilute the 28 kinds of compounds. The test was carried out using a three-chamber olfactometer (as shown in Figure 3 The specific operation steps are as follows: first, 100 μL of the test solution was dropped on the central part of the rubber lure core, and then 100 μL of n-hexane was added to the rubber lure core as a control. After the rubber lure core was completely absorbed, it was placed in the T box of the three-chamber olfactometer. At the same time, 10% honey water was placed in the T box and the C box as a food source for C. partell. Then, fresh air with a flow rate of 0.5 L / min was introduced from the AFP air inlet pipe of the T box and the R box, which had been dried by an activated carbon drying tower, and the exhaust fan at EF was turned on to exhaust the gas in the R box. The 1-day-old C. partell was released into the R box after 12 hours of starvation. The number of C. partell in the T box, C box and R box was observed and recorded every 2 hours, and the observation lasted for 12 hours. The whole test was carried out in a dark room with a temperature of 26°C±1°C and a humidity of 70%±5% RH. The test was repeated three times under the same conditions, and after each test, the three-chamber olfactometer was cleaned with 75% alcohol and pure water to remove the residual odor volatiles. The data obtained in the test were statistically analyzed using Excel 2016, and then analyzed using IBM SPSS Statistics 26 to calculate the selection rate, non-selection rate and BIV (Behavioral Index Value) of C. partell to the 28 kinds of compounds. Specifically, the selection rate = [C (or T) / (C+T+R)] * 100; the non-selection rate = [R / (C+T+R)] * 100; the BIV = [(C-T) / (C+T)] * 100%, and the BIV grade is shown in Table 2.

[0036] The results are shown in Table 3.Figure 4 As shown in Table 2, the test only shows 8 compounds that have attractive effect on both female and male adult of Spodoptera exigua, the strongest attractive effect is (+)-limonene, and the rest in order are: citral, a-pinene, butyl propionate, 2,4-dimethylacetophenone, L-linalool, butyl acrylate, butyl acetate.

[0037] Table 2BIV grade division

[0038]

[0039] Example 4 Different proportions of Spodoptera exigua attractant and screening thereof

[0040] Further, in order to strengthen the influence of single chemical substance on Spodoptera exigua, in this embodiment, 4 compounds with better attractive effect on Spodoptera exigua in Example 3 are compounded, specifically, different combinations of citral, a-pinene, butyl propionate and D-limonene are used to configure 11 attractant formulations (Mixture 1-11), and the specific test method is as shown in Example 3, and the details of each attractant formulation are shown in Table 3.

[0041] Table 3 Each attractant formulation

[0042]

[0043] As shown in Table 2, the test only shows 8 compounds that have attractive effect on both female and male adult of Spodoptera exigua, the strongest attractive effect is (+)-limonene, and the rest in order are: citral, a-pinene, butyl propionate, 2,4-dimethylacetophenone, L-linalool, butyl acrylate, butyl acetate. Figure 5 As shown in Table 2, the test only shows 8 compounds that have attractive effect on both female and male adult of Spodoptera exigua, the strongest attractive effect is (+)-limonene, and the rest in order are: citral, a-pinene, butyl propionate, 2,4-dimethylacetophenone, L-linalool, butyl acrylate, butyl acetate.

[0044] Table 4 BIV value of Spodoptera exigua to different attractant formulations

[0045]

[0046] Note: The table shows the average ± standard error, different lowercase letters represent significant difference (P <0.05), NR (no response, no significant difference in selection rate or BIV <10%), W (weak, 0 <BIV <30%), M (moderate, 30% <BIV <70%), S (strong, BIV >70%).

[0047] Example 4: Semifield trapping test of Spodoptera frugiperda attractant combination

[0048] To test the trapping effect of Mixtue 4, we conducted a semifield cage trapping test. This experiment evaluated and compared the trapping effects of two formulations, Formulation One: 50% a-pinene + 50% citral; Formulation Two: 40% a-pinene + 40% citral + 10% oxolide + 10% phenylacetaldehyde, which added the induction adjuvants phenylacetaldehyde and oxolide. The experiment was conducted in a net house (5m x 5m x 2.5m) at the experimental base of the Chinese Academy of Agricultural Sciences in Xinxiang County, Xinxiang City, Henan Province. Twenty-eight small trumpet stage corns were placed in the net house, and Figure 6 D was placed, 6 boat-shaped traps were placed around the center of the net house, 3 treatments and 3 controls, randomly interchanged, and 100 heads of S. frugiperda were released at the center of each treatment. The number of S. frugiperda in the traps was investigated daily, and the cumulative investigation was conducted for 7 days, with 3 repetitions.

[0049] As shown in Figure 6 A, the average number of S. frugiperda trapped in each net house treatment trap was 4.67±0.54, and the average number of S. frugiperda trapped in the control trap was 0.33±0.27, with a significant difference between the treatment and the control (t=5.814, df=4, P=0.004). Figure 6 B, the average number of S. frugiperda trapped in each net house treatment trap was 10.33±0.67, and the average number of S. frugiperda trapped in the control trap was 1±0.57, with a significant difference between the treatment and the control (t=10.580, df=4, P=0.001). Figure 6 C, the difference between the two formulations was significant (t=6.010, df=4, P=0.004), and the trapping effect was improved by about 54.89% after adding the induction adjuvants oxolide and phenylacetaldehyde based on a-pinene and citral as the base material. These results show that the attractant combination with a-pinene and citral as the base material has excellent effect in trapping S. frugiperda, and has important application potential in improving the efficient and specific food attractant of S. frugiperda and the prediction and control of S. frugiperda, which is expected to provide an efficient, environmentally friendly and targeted solution for the prevention and control of S. frugiperda in agricultural production.

[0050] The above disclosed are only specific embodiments of the present application, but the present application is not limited thereto, and any changes that can be thought of by those skilled in the art shall fall within the protection scope of the present application.

Claims

1. Use of an alpha-pinene and citral composition in the preparation of a Spodoptera frugiperda feeding lure, characterized in that, The composition is Formulation One or Formulation Two: The Formulation One is 50% alpha-pinene and 50% citral; The Formulation Two is 40% alpha-pinene, 40% citral, 10% oxolane and 10% phenylacetaldehyde.

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