Trichogramma japonicum attractant and application thereof
By using the rice borer red-eyed wasp attractant, D-limonene was used to attract rice borer red-eyed wasp to parasitize the eggs of rice borer, which solved the threat of rice borer to rice and achieved efficient and green environmentally friendly prevention and control effects.
Patent Information
- Application Number
- CN202510265732.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-06-03
AI Technical Summary
Rice leaf rolling borer poses a serious threat to rice. The existing control methods have problems such as chemical pesticide residues and increased pest resistance. We need to find effective green and environmentally friendly prevention and control methods.
The rice borer red-eyed bees attractant is used, and its effective component contains D-limonene. It attracts the rice borer red-eyed bees by releasing the smell of D-limonene, so that it can parasitize the rice borer eggs and prevent its growth.
It effectively improves the efficiency of pest control, is green and environmentally friendly, easy to promote, reduces the use of chemical pesticides, and reduces the risk of pest resistance and pesticide residues.
Smart Images
Figure CN120078022A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of plant protection, relates to the control technology of Cnaphalocrocis medinalis, and specifically relates to a Trichogramma japonicum attractant and its application. Background Art
[0002] The rice leaf folder, commonly known as the leaf roller and longitudinal leaf roller, belongs to the Pyralidae of Lepidoptera, and harms rice, barnyard grass, foxtail, sugarcane, wheat, etc. It is a common migratory pest. In recent years, its harm to rice in China has been increasing, posing a serious threat to rice yield.
[0003] The occurrence degree of the rice leaf folder is affected by factors such as the number of immigrant insect sources, climate conditions after immigration, rice varieties and growth vigor. Generally, cloudy, low light and high humidity are conducive to the occurrence of this disease, while drought and high temperature are unfavorable for its development. The adults like to inhabit in dense rice fields and lay eggs on young and tender rice seedlings. The larvae have a high survival rate when feeding on rice plants from the tillering stage to the booting stage, which is conducive to their development. Once the larvae of the rice leaf folder exceed the second instar, they will quickly roll the leaves, and it is difficult for the pesticides to contact the insect bodies after leaf rolling, resulting in poor control effect.
[0004] Trichogramma japonicum belongs to the Hymenoptera and Trichogrammatidae, and is distributed in Liaoning, Hebei, Henan, Shaanxi, Jiangsu, Zhejiang, Anhui, Jiangxi and other places. The host insects include Chilo suppressalis, Cnaphalocrocis medinalis, Naranga aenescens, Parnara guttata, etc. Since the advent of synthetic organic pesticides in the 1940s, due to problems such as the increase in pest resistance, pest resurgence and pesticide residues caused by the large use of chemical pesticides, the use of natural enemy insects to control pests has become increasingly important and superior. Because Trichogramma japonicum has the advantages of fast reproduction, good effect, labor saving, pollution-free and wide range of pest control, it is deeply welcomed by scholars and producers at home and abroad. It is currently the most effective natural enemy with the largest area of pest control and the most significant economic benefits at home and abroad.
[0005] In recent years, due to problems such as pesticide residues and pest resistance to crop diseases and pests, people have paid more attention to reducing the use of chemical agents and have more chosen to apply biological control technologies. Using natural enemy organisms in nature can control agricultural pests such as the rice leaf folder and is also beneficial to the increase in the number of beneficial organisms in the field. Summary of the Invention
[0006] Based on this, the purpose of the present invention is to provide a Trichogramma japonicum attractant and its application. The effective component of the attractant contains D-limonene, and the odor of D-limonene can attract Trichogramma japonicum. Trichogramma japonicum can parasitize on the eggs of Cnaphalocrocis medinalis when the rice is damaged by Cnaphalocrocis medinalis, so that Cnaphalocrocis medinalis stops growing. The application of this attractant can effectively improve the control efficiency of pests, and is green, environmentally friendly and easy to promote.
[0007] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention provides an attractant for Trichogramma japonicum, and the effective component of the attractant contains D-limonene.
[0008] Furthermore, the effective component is a single component of D-limonene.
[0009] Furthermore, the attractant is a solution containing the effective component, and the solvent of the solution is a volatile solvent.
[0010] Furthermore, the volatile solvent is selected from one or more of methylene chloride, n-hexane and acetone.
[0011] Furthermore, the amount ratio of D-limonene to the solvent in the solution is 100 - 1000 ng / μL.
[0012] Furthermore, the amount ratio of D-limonene to the solvent in the solution is preferably 150 - 600 ng / μL, and more preferably 200 - 500 ng / μL.
[0013] The present invention further provides an application of the attractant for Trichogramma japonicum in controlling Cnaphalocrocis medinalis.
[0014] Furthermore, the attractant for Trichogramma japonicum is directly sprayed in the rice field or made into a lure core, and then the lure core is placed in the rice field to release D-limonene to attract Trichogramma japonicum.
[0015] Furthermore, the attractant for Trichogramma japonicum is loaded on a slow-release carrier to obtain the lure core. The slow-release carrier can be made of materials with adsorption effects such as rubber, wood or sponge.
[0016] The present invention further provides a lure core used in controlling Cnaphalocrocis medinalis with the attractant for Trichogramma japonicum.
[0017] All applications of using D-limonene as the effective component of the attractant for Trichogramma japonicum, as well as the corresponding products and usage methods, are within the protection scope of the present invention.
[0018] The beneficial effects of the present invention are as follows: The present invention provides an attractant for Trichogramma japonicum. The effective component of the attractant contains D-limonene, which exists in rice itself and is green and safe. By directly spraying the attractant provided by the present invention in the rice field or making it into a lure core and then placing the lure core in the rice field to release D-limonene to attract Trichogramma japonicum, the control efficiency of pests can be effectively improved, and it is green, environmentally friendly and easy to promote. Description of the Drawings
[0019] To more clearly illustrate the technical solutions of the present invention, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0020] Appendix Figure 1 It is the analysis result diagram of the attraction ratio of the attractant in Example 1 and the solution in Comparative Example 1 to the female wasps of Trichogramma japonicum. Among them, a is the schematic diagram of the "Y" - tube, and b is the analysis result of D - limonene; Appendix Figure 2 For TPS20 It is the analysis result diagram of the gene expression level; Appendix Figure 3 It is the detection result diagram of the mutant gene. Among them, a is the agarose gel electrophoresis diagram, and b is the analysis diagram of the sequencing result; Appendix Figure 4 It is the analysis result diagram of the relative content of volatile D - limonene in wild - type and mutant plants under different egg treatments; Appendix Figure 5 It is the result diagram of observing the response of Trichogramma japonicum to wild - type and mutant plants with a Y - type olfactometer. Among them, a is the comparison diagram of wild - type and mutant plants, and b is the comparison diagram when adding lure cores without D - limonene and with D - limonene beside the mutant plants; Appendix Figure 6 It is the analysis result diagram of the behavioral selection of Trichogramma japonicum for rice plants with eggs at different developmental times; Appendix Figure 7 It is the result diagram of the collection and analysis of volatile substances from rice plants. Among them, a is the result of principal component analysis, b is the analysis result of the quantity and type of volatile substances, and c - f are the relative quantity analysis results of different types of volatile substances respectively; Appendix Figure 8 It is the analysis result diagram of the attraction ratio of volatile substances with different concentrations to female wasps of Trichogramma japonicum. Among them, a is the schematic diagram of the "Y" - tube, b is the analysis result of 3 - carene, c is the analysis result of 2,4 - dimethyl - 1 - heptene, and d is the analysis result of o - cymene. Detailed implementation manners
[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings. All the mentioned embodiments are implemented on the premise of the technical solutions of the present invention, and detailed implementation processes are given. However, it should be stated that the protection scope of the present invention is not limited to the following embodiments.
[0022] The Trichogramma japonicum used in the embodiments of the present invention and related researches ( Trichogramma japonicum ) is in a glass tube (diameter 3.5 cm, height 20 cm) with inactivated Corcyra cephalonica (Corcyra cephalonica Rearing was carried out with eggs and a 20% aqueous honey solution was provided. To ensure mating, the newly emerged Trichogramma japonicum were placed together for at least 6 hours before using female Trichogramma japonicum for the experiment. All insects were reared in a greenhouse under a photoperiod of 16:8 (light:dark), a temperature of 27 ± 1 °C, and a relative humidity of 70 ± 5%.
[0023] The rice varieties used in the examples and related studies of the present invention Oryza sativa include Minghui 63 (MH63) and Zhonghua 11 (ZH11). The rice variety Zhonghua 11 (ZH11) includes wild type (W, Oryza sativa + / +) and a mutant (M) with impaired function of terpene synthase 20 gene TPS20 ( TPS20 - / -). Seedlings were cultured in a greenhouse under a photoperiod of 16:8, a relative humidity of 75 ± 5%, and a temperature of 27 ± 1 °C as described previously (Hu et al., 2020, eLife 2020 Vol.9 e55421). Rice plants at the tillering stage with 3 tillers and 4 leaves on the main stem were selected for the experiment. In addition, Cnaphalocrocis medinalis was reared with corn seedlings (Zhengdan 958) and placed in the same greenhouse as the rice.
[0024] Example 1 Trichogramma japonicum attractant and its application Analytical pure D-limonene (Sigma-Aldrich, St. Louis, Missouri, USA) was dissolved in n-hexane to form an attractant, and a sample solution of 200 ng / μL was prepared and stored at -80 °C for later use.
[0025] 10 μL of the attractant containing D-limonene was dropped onto a filter paper strip (1 × 2 cm), which was used as an odor source to attract Trichogramma japonicum.
[0026] Control experiment to verify the effect 10 μL of the attractant containing D-limonene and pure n-hexane (used as a blank control) were respectively dropped onto filter paper strips (1 × 2 cm), which were used as odor sources. The behavioral responses of Trichogramma japonicum were observed using a "Y"-tube olfactometer. The filter paper strip and the control in Example 1 above were used as odor sources to test 8 female Trichogramma japonicum, and new odor sources were replaced. A total of 120 female Trichogramma japonicum were tested (from 10:00 to 15:00). Individuals that did not make a choice within 5 minutes were not included in the data analysis. The verification results are as Figure 1 shown.
[0027] Comparative Example 1 and its effect Analytical pure D-limonene (Sigma-Aldrich, St. Louis, MO, USA) was dissolved in n-hexane to form a solution, and a sample solution with a concentration of 5 ng / μL was prepared and stored at -80°C for later use. 10 μL of this solution containing D-limonene and pure n-hexane were respectively dropped onto filter paper strips (1×2 cm), which were used as odor sources. The behavioral responses of Trichogramma japonicum were observed using a "Y"-tube olfactometer. The above filter paper strips were used as odor sources to test 8 female Trichogramma japonicum. After replacing the new odor source, a total of 120 female Trichogramma japonicum were tested (from 10:00 to 15:00). Individuals that did not make a choice within 5 minutes were not included in the data analysis. The verification results are as Figure 1 shown.
[0028] As Figure 1 shown, the control experiment of the attractant in Example 1 and the effect test of Comparative Example 1 showed that the attractant in Example 1 had a significant attracting effect on female Trichogramma japonicum, while the n-hexane control and the solution in Comparative Example 1 had no attracting effect on female Trichogramma japonicum.
[0029] To further prove the technical effect of the present invention, the inventors conducted in-depth research on the biological principle of the attractant of the present invention, and the following research content confirmed the attracting principle.
[0030] Experiment for confirming the attracting principle of the attractant (including the examples of the lure core and its application of the present invention) It is reported that terpene synthase 20 ( OsTPS20 ) is responsible for the production of limonene in rice (Chen et al., 2018, Plant Biotechnol J, 16(10), 1778-1787; Qiu et al., 2024, Plant biotechnology journal 2024P1). The inventors of the present invention conducted real-time fluorescence quantitative PCR experiments to further explore the gene function. For four treated rice plants (PCE1, PCE2, PCE3, and PCE4) and rice plants without the eggs of Cnaphalocrocis medinalis (PWE), total RNA of rice leaf tissues induced by eggs of different ages was extracted using TRIzol reagent (each three rice plants were used as a sample, with a total of three replicates). Then, 1 μg of total RNA was used to synthesize cDNA. The gene expression levels were detected using the primers listed in Table S1.
[0031] The preparation process of four types of plants carrying eggs of Cnaphalocrocis medinalis (PCE) is as follows: Place a main tiller into a 500 - milliliter plastic cup, and add 5 gravid female moths of Cnaphalocrocis medinalis. Let the moths lay eggs on the leaves at night (from 8:00 p.m. to 8:00 a.m. the next day). Then select the plants with 150 - 200 eggs, and keep them in a climate chamber (27 ± 1 °C, relative humidity of 70 ± 5%, light cycle L16:D8) for 0, 1, 2, and 3 days respectively, and label them as rice plants carrying 1 - day - old eggs (PCE1), 2 - day - old eggs (PCE2), 3 - day - old eggs (PCE3), and 4 - day - old eggs (PCE4).
[0032] As Figure 2 the fluorescence quantitative results show that TPS20 the expression level of the
[0033] gene can be enhanced with the increase of egg induction time (df = 4; F = 227.34; P < 0.001), and the highest expression is in the leaves carrying 2 - day - old eggs. TPS20 To confirm the effect of D - limonene on Trichogramma japonicum, knockout mutant rice plants (LOC_Os04g27190, Figure 3 - / -) were created from the Zhonghua 11 (ZH11) variety using the CRISPR / Cas9 system. Genomic DNA was extracted using the CTAB method. Then, specific primers (Table S1) were used for PCR and DNA agarose gel electrophoresis to determine the authenticity of the mutant lines. In addition, the PCR products were sequenced and analyzed. The mutant detection results are shown in TPS20 Figure 3a and 3b, and the results show that
[0034] Compared with the wild - type rice plants (ZH11), the - / - mutant plants (ZH11) have a 550 - base deletion. Volatile substances of wild - type and mutant plants under different egg treatments were analyzed to determine the ability of mutant rice plants to produce D - limonene. Three groups of mutant odor - source plants were prepared, with three groups of wild - type odor - source plants as the control group, and the plant volatiles were collected. The plants are as follows: (i) Mutant plants without eggs (M);
[0035] (ii) Mutant plants carrying 2 - day - old eggs (M2); (iii) Mutant plants carrying 3 - day - old eggs (M3). (iv) Wild - type plants without eggs (W); The test results of the volatiles are shown in Figure 4As shown, the results showed that the relative content of D-limonene in W2 was significantly increased compared with that in W and W3 (df = 2; F = 129.73; P < 0.001). Although the content trend of D-limonene in M, M2, and M3 was similar to that in W, W2, and W3 (df = 2; F value = 2.95; P < 0.001), D-limonene was not detected in M plants, and only trace amounts of D-limonene were detected in M2 and M3 plants. This indicates that the function of producing D-limonene is missing in the gene knockout rice plants lacking D-limonene synthesis when damaged by Cnaphalocrocis medinalis Guenée.
[0036] To verify the attracting effect of the lure core containing D-limonene on Trichogramma japonicum, the present invention prepared an attractant with a ratio of D-limonene to n-hexane of 500 ng / μL. A pipette was used to aspirate 100 μL of the prepared attractant solution and inject it into a natural desulfurized rubber stopper (Keyun Biology, sex pheromone carrier) to make a lure core (the lure cores used in the specific embodiments of the present invention were all made in this way), and pure n-hexane solvent was used as a control. The following four pairs of different rice plants were prepared, and the reaction of Trichogramma japonicum was observed using a Y-tube olfactometer: (i) Wild-type plants (W2) carrying 2-day-old eggs and mutant plants (M2) carrying 2-day-old eggs; (ii) Wild-type plants (W4) carrying 4-day-old eggs and mutant plants (M4) carrying 4-day-old eggs; (iii) Wild-type plants (WH2) carrying 2-day-old eggs and having 100 μL of n-hexane in the lure core and mutant plants (ML2) carrying 2-day-old eggs and having 100 μL of D-limonene (500 ng / μL) in the lure core; (iv) Wild-type plants (WH4) carrying 4-day-old eggs and having 100 μL of n-hexane in the lure core and mutant plants (ML4) carrying 4-day-old eggs and having 100 μL of D-limonene (500 ng / μL) in the lure core.
[0037] As Figure 5 shown, the olfactory results of Trichogramma japonicum showed that they had a significant preference for W2 (Binomial test, P = 0.005); while when choosing between the odors of W4 and M4 plants, they did not show a preference (P = 0.207) ( Figure 5 a). Compared with WH4, Trichogramma japonicum could be significantly attracted by the rice plants treated with ML4 (P < 0.001); however, this preference was no longer observed between WH2 and ML2 (P = 0.897) ( Figure 5 b).
[0038] The above results indicate that the gene knockout rice plants lacking D-limonene synthesis lose their attractiveness to Trichogramma chilonis, but the attractiveness can be restored by adding a lure releasing D-limonene beside the gene knockout plants.
[0039] The above results also indicate that wild-type plants carrying 2-day-old eggs have a strong attraction to Trichogramma chilonis. The following research by the inventors also serves as the same proof.
[0040] Prepare five rice plants (Minghui 63): plants without eggs (PWE) and four plants carrying eggs of Cnaphalocrocis medinalis (PCE). To obtain plants carrying eggs of Cnaphalocrocis medinalis, place a main tiller in a 500-ml plastic cup and add 5 gravid female moths of Cnaphalocrocis medinalis, allowing the moths to lay eggs on the leaves at night (from 8:00 p.m. to 8:00 a.m. the next day). Then select plants with 150 - 200 eggs and keep them in a climate chamber (27 ± 1°C, 70 ± 5% relative humidity, light period L16:D8) for 0, 1, 2, and 3 days respectively, and label them as rice plants carrying 1-day-old eggs (PCE1), 2-day-old eggs (PCE2), 3-day-old eggs (PCE3), and 4-day-old eggs (PCE4).
[0041] To determine the preference of female Trichogramma chilonis for rice plants with eggs of different ages, prepare the following paired odor sources: (i) PWE and PCE1; (ii) PWE and PCE2; (iii) PWE and PCE3; (iv) PWE and PCE4.
[0042] Use a dual-choice (Y-tube) olfactometer to observe the behavioral responses of Trichogramma chilonis as described previously (Hu et al., 2020, eLife 2020 Vol.9 e55421; Yao et al., 2022, New Phytol, 237,2375–2387). Specifically, place four rice plants treated in the same way in a glass bottle as an odor source. Test 8 female Trichogramma chilonis for each source combination separately every day, and use new odor sources every day. A total of 60 - 120 female Trichogramma chilonis (from 10:00 to 15:00) are tested for each odor source combination. Individuals that do not make a choice within 5 minutes are not included in the data analysis.
[0043] The results of the "Y"-type olfactometer are as Figure 6 shown, and the results show the behavioral choices of Trichogramma chilonis for rice plants with eggs of different developmental times. It is found that compared with healthy rice plants, Trichogramma chilonis significantly tends to choose the rice plants 2 days after Cnaphalocrocis medinalis lays eggs, and has no significant selective response to the rice plants with eggs 1, 3, and 4 days after oviposition.
[0044] Based on the conclusive confirmation of the above two experiments by the inventors, wild-type plants carrying 2-day-old eggs have a strong attraction to Trichogramma japonicum. Based on this, other volatiles of wild-type plants carrying 2-day-old eggs can be used as a comparative example for D-limonene in the application of Trichogramma japonicum attractant to highlight the remarkable effects and creativity of the present invention.
[0045] The method for collecting and analyzing the volatiles of wild-type rice plants carrying eggs of Cnaphalocrocis medinalis is as follows: Use a dynamic headspace collection system to collect the volatiles released by the plants (PWE, PCE1, PCE2, and PCE3) (Chen et al., 2018, Plant Biotechnol J, 16(10), 1778-1787). Specifically, four rice plants of the same treatment are placed in a glass bottle (3142 ml) as a replicate. The air is first filtered successively through activated carbon, silica gel Rubin (Sigma-Aldrich), and molecular sieve (Sigma-Aldrich), and then pumped into the glass bottle at a rate of 400 ml / min for 30 minutes using a pump (QC-1S, Beijing, China) to remove impure air. Subsequently, a glass tube containing 20 mg of Super Q adsorbent (80 / 100 mesh, Shanghai, China) is connected to the air outlet, and the headspace volatiles released by the rice plants are trapped for 4 hours (11:00-15:00) under greenhouse conditions (27±1°C, relative humidity 75±5%). The volatiles adsorbed on the adsorbent are eluted with 200 μl of dichloromethane, and 500 ng of nonyl acetate is added to the eluate as an internal standard.
[0046] The samples containing volatiles were analyzed using a gas chromatography - mass spectrometer (GC - MS, Agilent 8890 / 5977B, Agilent Technologies Co., Ltd., Beijing, China), and the analysis conditions were as described in previous studies (Chen et al., 2018, Plant Biotechnol J, 16(10), 1778 - 1787). Based on the mass spectra of the volatiles and the retention times of the authentic standards, the compounds were matched with those in the NIST library (Scientific Instrument Services, Inc, Ringoes, NJ, USA) to confirm their identities (Hu et al., 2020, eLife 2020 Vol.9 e55421; Liu et al., 2021, Nat Commun, 12(1), 6772). The relative quantification of the compounds was based on their integrated areas relative to the internal standard (DeLange et al., 2020, J ChemEcol, 46(3), 344 - 360). Finally, the differential compounds between different treatments were analyzed. For each treatment, the materials collected from four rice plants in each bottle were used as one biological sample, and each treatment was repeated 5 - 6 times.
[0047] Using headspace dynamic collection and GC - MS analysis, it was found that 26 compounds were detected in rice plants without eggs (PWE) and rice plants with eggs of different ages. The results of the principal component analysis are as Figure 7 shown, and the results indicate that the volatiles of healthy rice plants and those induced by eggs of different ages can be clearly distinguished ( Figure 7 a); in addition, the quantity and types of volatiles of rice plants induced by eggs of different ages and healthy rice plants are basically the same, and the relative amounts of 5 volatiles induced by 2 - day - old eggs ( Figure 7 1 is 3 - carene, 2 is 2,4 - dimethyl - 1 - heptene, 3 is p - cymene, 4 is D - limonene, and 5 is α - pinene in b) are significantly increased compared with other treatments ( Figure 7 b - f).
[0048] Based on the above results, the following comparative examples were set up to further highlight the creativity of the present invention.
[0049] Comparative Example 2 and its effects Using the same experimental methods as in Example 1 and Comparative Example 1, high - dose and low - dose aliquots were prepared with 3 - carene, 2,4 - dimethyl - 1 - heptene, and p - cymene respectively, and the attracting effects were verified. The high - and low - dose concentrations of each volatile and the verification results are as Figure 8 shown, and the results indicate that these three substances have no significant effect on the behavioral responses of female Trichogramma japonicum Ashmead whether at low concentration or high concentration. Through comparison, the significant effect of the present invention is further highlighted.
[0050] The foregoing description of the present invention enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.
Claims
1. A rice borer trichogrammatid attractant, characterized in that: The efficacy component of the attractant contains D-limonene.
2. The rice borer trichogramma attractant as claimed in claim 1, characterized in that The efficacy component is a single component of D-limonene.
3. The rice borer trichogramma attractant as claimed in claim 2, characterized in that The attractant is a solution containing an effective component, and the solvent of the solution is a volatile solvent.
4. The rice borer trichogramma attractant as claimed in claim 3, characterized in that The volatile solvent is selected from one or more of dichloromethane, n-hexane and acetone.
5. The rice borer trichogramma attractant as claimed in claim 3, characterized in that The amount ratio of D-limonene to the solvent in the solution is 100-1000 ng / μL.
6. The rice borer trichogramma attractant as claimed in claim 5, characterized in that The amount ratio of D-limonene to the solvent in the solution is 150-600 ng / μL.
7. Use of the Trichogramma attractant as claimed in any one of claims 1 to 6 in controlling rice leaf folder.
8. The use according to claim 7, characterized in that The rice borer trichogrammatid attractant is directly sprayed on the rice field or made into an attractant core and the attractant core is placed in the rice field to release D-limonene to attract the rice borer trichogrammatid.
9. The use according to claim 8, characterized in that The attractant is loaded on a slow-release carrier to obtain the attractant core.
10. An attractant for use as claimed in claim 8 or 9.