Application of dihydrocarvone in insect attractants

Abstract

This invention belongs to the technical field of insect attractants, specifically the application of dihydrocarvone in insect attractants. The invention provides the application of dihydrocarvone as an insect attractant. First, dynamic headspace adsorption technology is used to collect alfalfa volatiles. The collected volatiles are then separated and identified by GC-MS. A Y-type olfactometer is used to determine the selective behavior of *O. loli* and *F. occidentalis* towards the volatiles. The results show that both thrips are attracted to dihydrocarvone. This substance can be used as a novel attractant for thrips pest control, providing a new option for thrips control.

Description

Technical Field

[0001] This invention belongs to the technical field of insect attractants, and relates to the application of dihydrocarvone in insect attractants. Background Technology

[0002] Thrips are a general term for insects in the order Thysanoptera. They are micro to small, ranging from 0.5 to 14 mm in length, and reproduce parthenogenetically or sexually. Most species are herbivorous or fungivorous, while a few are predatory or saprophagous. The vast majority of herbivorous species are pests of agricultural and forestry crops. The bull-horned thrips (Odontothrips loti Haliday) is an oligophagous pest that damages leguminous forage grasses such as alfalfa and sweet clover. It uses its rasping-sucking mouthparts to rupture the plant epidermis and inserts its stylet into the tissue to extract sap. Damaged areas often leave yellow spots or streaks, eventually leading to wrinkling, wilting, and death. Furthermore, its feeding process can transmit plant viral diseases. The western flower thrips (Frankliniella occidentalis Pergande) is a polyphagous pest with over 500 host species. It has high reproductive capacity, strong concealment, and strong pesticide resistance, making control difficult and seriously impacting the development of my country's alfalfa industry.

[0003] Currently, chemical control is the primary method for thrips control. However, the high reproductive rate, frequent outbreaks, stealthy nature, and evolving resistance to pesticides of thrips greatly increase the difficulty of control efforts. Therefore, how to safely and effectively control thrips damage and explore new approaches to thrips control has become an urgent problem to be solved.

[0004] The ability of insects to locate their hosts using volatile substances offers a potential avenue for developing green attractants. Attractants play a crucial role in monitoring insect population dynamics and intensive trapping. Previous studies have identified various volatiles in alfalfa, aiming to screen for substances that attract thrips and provide an effective attractant for monitoring and trapping thrips population dynamics. Summary of the Invention

[0005] The purpose of this invention is to provide the application of dihydrocarvone in insect attractants, offering a new option for thrips control.

[0006] For the purposes described above, this application addresses this need in the field by providing the application of dihydrocarvone in insect attractants.

[0007] On the one hand, the present invention relates to the application of dihydrocarvone in insect attractants. Firstly, by collecting volatiles from alfalfa, and then separating and identifying them, it was confirmed that dihydrocarvone has a significant attraction to male and female horn-toothed thrips. Thus, dihydrocarvone can be used as an insect attractant.

[0008] Furthermore, the application of dihydrocarvone provided by the present invention in insect attractants is used for attracting horn-toothed thrips and / or western flower thrips.

[0009] The molecular structure of the dihydrocarvone is shown below:

[0010]

[0011] Furthermore, the application of (+)-dihydrocarvone provided by the present invention in insect attractants, wherein the attractant concentration of (+)-dihydrocarvone is 10-1000 ng / μl.

[0012] On the other hand, the present invention relates to a lure for attracting thrips, the lure comprising (+)-dihydrocarvone and liquid paraffin oil, forming a new lure as a product.

[0013] Compared with the prior art, the present invention has the following beneficial effects or advantages:

[0014] The (+)-dihydrocarvone provided by this invention was isolated and identified. Y-type olfactory testing showed that both male and female *Thrips hornbillii* were significantly attracted to (+)-dihydrocarvone at a concentration of 10 ng / μl; female *Thrips przewalskii* were significantly attracted to (+)-dihydrocarvone at a concentration of 100 ng / μl. This (+)-dihydrocarvone attractant, derived from a natural plant component, exhibits significant attractant activity against both *Thrips hornbillii* and *Thrips przewalskii* at low concentrations. It is characterized by its green, high-efficiency, and broad-spectrum activity, providing a new option for thrips control and showing promising application prospects. Attached Figure Description

[0015] Figure 1 Total ion chromatogram of volatiles from fresh leaves of Baralfa 421Q alfalfa variety.

[0016] Figure 2 This is a comparison of the mass spectrum of (+)-dihydrocarvone, a volatile compound from alfalfa, with the NIST mass spectrum library.

[0017] Figure 3 A schematic diagram of a Y-shaped olfactory sensor used for thrips behavior measurement.

[0018] Figure 4 The behavioral response of *Thrips hornbillii* to (+)-dihydrocarvone.

[0019] Figure 5 The behavioral response of western flower thrips to (+)-dihydrocarvone. Detailed Implementation

[0020] The technical solution of the present invention will be described below with reference to the embodiments. However, the present invention is not limited to the following embodiments.

[0021] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0022] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0023] Example

[0024] This embodiment provides a method for the isolation and identification of (+)-dihydrocarvone.

[0025] Test reagent: (+)-dihydrocarvone (p-Menth-8-en-2-one) was identified in alfalfa cultivar Baralfa 421Q. The sample was purchased from Sigma-Aldrich and had a purity of 98%. The solvent was liquid paraffin oil (analytical grade, S10187, SCRC).

[0026] Collection of alfalfa volatiles: Dynamic headspace adsorption (DHA) was used to collect alfalfa volatiles. Potted alfalfa plants were wrapped in aluminum foil around the pots and soil surface, with three pots placed in a clean gas collecting bottle. The bottle was sealed with sealing film to prevent leakage. The bottle was connected to a vacuum pump. Before collection, the gas was purged at the maximum flow rate (400 ml / min) for 30 minutes. After purging, adsorbent was added to the vacuum pump. Gas collection continued for 8 hours (9:00-17:00). The adsorbent was then eluted with 200 μl of a 1 ng / μl nonyl acetate solution. The eluent was collected in a 2 ml sample vial containing a liner and stored at -20℃. The experiment was repeated 6 times, with each potted alfalfa plant collected only once.

[0027] Air drawn in by an atmospheric sampler (QC-1B type) passes sequentially through activated carbon, molecular sieve, silica gel, a gas collection bottle, and a 400 ml / min flow meter. Finally, it is filtered through a glass tube containing 30 mg of adsorbent to capture alfalfa volatile molecules. After the adsorbent is added to the glass tube, it is fixed with a small amount of glass wool, rinsed with 1 ml of dichloromethane, and connected to the gas collection device only after the dichloromethane has completely evaporated.

[0028] Separation and identification of volatiles: The collected volatiles were separated and identified using Shimadzu GC-MS QP2010PLUS. The selected column was an Rtx-5MS (30.0m × 0.25mm × 0.25μm). The GC program for headspace volatile identification of alfalfa was 44 min in total duration, with an initial temperature of 50℃, held for 1 min, then increased to 230℃ at a rate of 5℃ / min, held for 0 min; followed by an increase to 280℃ at a rate of 25℃ / min, held for 5 min. The injection port temperature was 250℃, splitless injection was used, and the injection volume was 10 μl; helium was used as the carrier gas at a flow rate of 1 ml / min. The total ion chromatogram of volatiles from fresh leaves of Baralfa 421Q alfalfa is shown below. Figure 1 As shown in the figure, (+)-dihydrocarvone was identified in the volatiles of fresh leaves of Baralfa 421Q alfalfa, with a peak time of 13.31 minutes. The mass spectrum of (+)-dihydrocarvone volatiles from alfalfa was compared with the NIST mass spectrum library. Figure 2 As shown.

[0029] This embodiment provides the effect of (+)-dihydrocarvone on the behavioral selection of two thrips.

[0030] Experimental Methods: The selective behavior of adult male and female *Thrips hornbill* and *Thrips serratus* towards (+)-dihydrocarvone was determined using a Y-type olfactory instrument. The Y-type instrument was made of transparent glass, with a main tube and two arms measuring 11 cm in length and 1 cm in inner diameter, and the included angle between the arms being 75°. (Y-type olfactory instrument...) Figure 3 The following components were connected sequentially: a Y-tube, a glass rotor flowmeter (LZB-3WB), a sample loading bottle (100ml), distilled water (250ml gas washing bottle), an activated carbon drying tower, and an atmospheric sampler. All connections were made with Teflon tubing. The atmospheric sampler was controlled at a flow rate of 50ml / min. 50μl of (+)-dihydrocarvone sample and 50μl of control sample (liquid paraffin oil) were added to each sample loading bottle as odor sources. An LED light panel (28W) was placed at the Y-end of the Y-tube olfactory instrument as the sole induction light source. The ambient temperature was maintained at 26±1℃, and the experiment was conducted between 10:00 and 17:00 during the day.

[0031] Thrips, 3-5 day old female and male adults, were selected. Each thrips was introduced one by one into the center of the Y-tube main tube, and the number entering each arm of the olfactory instrument was recorded. Timing began after the thrips were introduced into the main tube. If a thrips reached halfway through each arm within 5 minutes and remained there for more than 10 seconds or more than two-thirds of the way, it was considered that they had selected the odor source; otherwise, it was considered that they had not responded. To avoid the position effect, the odor source was swapped after testing 5 thrips. To avoid the influence of residual odor from the thrips, a new Y-tube was used after testing 10 thrips. The Y-tube was cleaned with 75% ethanol and baked at 60°C for 30 minutes. The experiment was repeated 60 times, and each test insect was used only once.

[0032] After testing with a Y-type olfactory sensor, the results were as follows: Figure 4 and Figure 5 As shown, compared with the control liquid paraffin oil, male and female horn-toothed thrips were significantly attracted to (+)-dihydrocarvone at 10 ng / μl; female western flower thrips were significantly attracted to (+)-dihydrocarvone at 100 ng / μl.

[0033] As described above, the present invention can be well implemented. The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, all changes and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the present invention.

Claims

1. The application of (+)-dihydrocarvone in insect attractants, characterized in that, Used for attracting horned thrips and / or western thrips; The inducing concentration of (+)-dihydrocarvone is 10-1000 ng / μL.

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