Parasitoid attractant and use thereof

Abstract

The application provides a parasitic wasp attractant and application thereof, and belongs to the technical field of pest control. The parasitic wasp attractant provided by the application comprises an active ingredient and an organic solvent, the active ingredient is citral, and the concentration of citral in the parasitic wasp attractant is >2 ng / µL. The application adopts citral as the active ingredient of the parasitic wasp attractant, and citral shows a high and stable attracting effect on parasitic wasps such as aphelinids even under trace conditions, so as to be beneficial to improving the parasitization rate and mortality rate of field pests such as whiteflies (specifically, whitefly nymphs). In addition, the application adopts citral as the active ingredient, citral is not only widely sourced and low in cost, but also is environment-friendly and does not cause harm to non-target organisms, and thus conforms to the development trend of modern green agriculture.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pest control, in particular to a parasitic wasp attractant and application thereof. BACKGROUND

[0002] Whitefly such as Bemisia tabaci is a global important agricultural pest, which can directly damage crops by sucking plant sap and transmit multiple plant viruses, leading to more serious economic losses. Although traditional chemical pesticides can effectively control whitefly populations in the short term, long-term use will lead to increased pest resistance, environmental pollution, and pesticide residues in agricultural products exceeding the standard. Biological control as a sustainable alternative solution has received increasing attention. Among them, using natural enemies of insects for pest control is an important part of biological control.

[0003] Encarsia formosa is a natural enemy of insects in the family Aphelinidae of the order Hymenoptera, which is an important parasitic wasp that can control whitefly pests. Encarsia formosa has achieved large-scale breeding and commercial production, and has been widely used in the integrated management of whitefly pests in greenhouse vegetables, flowers and other crops worldwide. Although Encarsia formosa has been proven to be an important natural enemy of whitefly pests, its parasitic efficiency is affected by various factors such as environmental conditions and host density, and the control effect is often not ideal, which limits its wide application.

[0004] The use of parasitic wasp attractants can improve the biological control effect of parasitic wasps on field pests. For Encarsia formosa, the components of plant volatiles, myrcene and caryophyllene, have been shown to have certain attractivity to the parasitic wasp, but the attractivity of the parasitic wasp still needs to be improved. SUMMARY

[0005] The present application aims to provide a parasitic wasp attractant and its application. The parasitic wasp attractant provided by the present application has excellent attractivity to parasitic wasps such as Encarsia formosa.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a parasitic wasp attractant, which comprises an active ingredient and an organic solvent, wherein the active ingredient is citral, and the concentration of citral in the parasitic wasp attractant is > 2 ng / μL.

[0008] Preferably, the concentration of citral in the parasitic wasp attractant is 20-2000 ng / μL.

[0009] Preferably, the concentration of citral in the parasitic wasp attractant is 100-200 ng / μL.

[0010] Preferably, the organic solvent comprises one or more of paraffin oil, dichloromethane and ethanol.

[0011] The application provides application of the parasitic wasp attractant in the above technical solution to attracting parasitic wasps for biological control of field pests.

[0012] Preferably, the parasitic wasp comprises Aphelinus gossypii.

[0013] Preferably, the pest comprises whitefly.

[0014] Preferably, the whitefly comprises Bemisia tabaci and / or Trialeurodes vaporariorum.

[0015] Preferably, the method for biological control of field pests comprises: adsorbing the parasitic wasp attractant into a carrier material, and hanging the carrier material containing the parasitic wasp attractant in a field.

[0016] Preferably, the carrier material comprises a rubber head and / or a capillary tube.

[0017] The application provides a parasitic wasp attractant comprising an active ingredient and an organic solvent, wherein the active ingredient is citral, and the concentration of citral in the parasitic wasp attractant is greater than 2 ng / μL. 10 H 16 O), also known as citronellal or 3,7-dimethyl-2,6-octadienal, is a naturally occurring monoterpene compound with a strong lemon fragrance. As an active ingredient of the parasitic wasp attractant, citral shows a high and stable attraction effect on parasitic wasps such as Aphelinus gossypii even under a trace amount condition, thereby facilitating an increase in parasitization rate and mortality rate of field pests such as whitefly (specifically, whitefly nymphs). In addition, the application of citral as the active ingredient is not only widely available and low in cost, but also environmentally friendly and harmless to non-target organisms, which conforms to the development trend of modern green agriculture. The results of the embodiments show that, compared with eight volatile compounds including beta-myrcene, 3-hexenal, methyl salicylate, 3-carene, caryophyllene, alpha-phellandrene, humulene and beta-myrcene, citral has good attraction activity on Aphelinus gossypii, and is suitable as the active ingredient of the parasitic wasp attractant. Meanwhile, the application of citral as the active ingredient can significantly enhance the foraging activity of Aphelinus gossypii at a lower concentration, improve the ability of Aphelinus gossypii to locate and parasitize whitefly nymphs, and increase the field parasitization rate of parasitic wasps, thereby achieving the effect of efficient control of field pests by parasitic wasps. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A schematic diagram of a Y-odorimeter used in the embodiments of the present application. DETAILED DESCRIPTION

[0019] The present application provides a parasitoid attractant, comprising an active ingredient and an organic solvent, wherein the active ingredient is citral, and the concentration of citral in the parasitoid attractant is > 2 ng / μL.

[0020] The parasitoid attractant of the present application only uses citral as the active ingredient, and does not need to additionally use other substances as the active ingredient, so that a good attracting effect on parasitoids can be achieved, the parasitoid attractant has high specificity when used in biological control of agricultural pests, can improve the searching efficiency and parasitization success rate of parasitoids such as aphelinid wasps on pests such as whiteflies in the field, can prolong the action time and stability of the attractant, is conducive to promoting the development of biological control technology, reducing the use of chemical pesticides, and protecting the ecological environment, and has low cost and is convenient for large-scale popularization and application. The parasitoid attractant of the present application is described in detail below.

[0021] As an embodiment of the present application, the concentration of citral in the parasitoid attractant can be 20-2000 ng / μL, and specifically can be 20 ng / μL, 50 ng / μL, 100 ng / μL, 150 ng / μL, 180 ng / μL, 200 ng / μL, 220 ng / μL, 250 ng / μL, 300 ng / μL, 400 ng / μL, 500 ng / μL, 800 ng / μL, 1200 ng / μL, 1500 ng / μL or 2000 ng / μL.

[0022] As an embodiment of the present application, the organic solvent can comprise one or more of paraffin oil, dichloromethane and ethanol, and specifically can be paraffin oil, dichloromethane or ethanol.

[0023] The present application does not have special limitations on the preparation method of the parasitoid attractant, and the active ingredient can be directly dissolved in the organic solvent.

[0024] The present application provides the application of the parasitoid attractant described in the above technical solution in attracting parasitoids for biological control of pests in the field. The present application uses citral as the volatile attractant, which is a natural product existing in plants, has low toxicity, is easy to degrade, and is friendly and safe to humans, livestock and the ecological environment. Compared with the existing pest attractants on the market, the parasitoid attractant provided by the present application is used for attracting beneficial parasitoids, which eliminates the concern of the planters that more pests will be attracted to their fields. The more beneficial insects, the better the control effect in the field. When applied to biological control of pests in the field, the parasitization rate of parasitoids on pests in the field is improved through the attracting effect of parasitoids, so that the effect of parasitoids on controlling pests in the field is achieved.

[0025] As one embodiment of the present application, the parasitic wasp can specifically include a Aphidoidea, which can be a female Aphidoidea, specifically a female Aphidoidea adult; the pest can specifically include a whitefly, which can include a Bemisia tabaci and / or a Trialeurodes vaporariorum, specifically a nymph of the Bemisia tabaci and / or a nymph of the Trialeurodes vaporariorum.

[0026] As one embodiment of the present application, the method for biological control of field pests can include: adsorbing the parasitic wasp attractant into a carrier material, and hanging the carrier material containing the parasitic wasp attractant in the field; the carrier material can include a rubber head and / or a capillary tube, and in the present embodiment, the attracting effect of the parasitic wasp attractant is verified by using asbestos as the carrier material. The present application does not have special limitations on the adsorption method and the amount of the parasitic wasp attractant and the carrier material, and the carrier material can be specifically immersed in the parasitic wasp attractant, and the parasitic wasp attractant can be fully adsorbed on the carrier material. As one embodiment of the present application, the carrier material adsorbed with the parasitic wasp attractant can be placed in a slow-release device, and the biological control of field pests can be performed by simultaneously releasing the Aphidoidea; the slow-release device can be specifically a slow-release device that is breathable but not liquid-permeable, and the present application does not have special limitations on the specific type and structure of the slow-release device.

[0027] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] The reagents used in the following experiments are all commercially available goods well known to those skilled in the art.

[0029] The slow-release device used in the following experiments is air-permeable but liquid-impermeable. For details, refer to the literature (von Mérey, G., Veyrat, N., Mahuku, G., Valdez, R.L., Turlings, T.C., & D'Alessandro, M. (2011). Dispensing synthetic green leaf volatiles in maize fields increases the release of sesquiterpenes by the plants, but has little effect on the attraction of pest and beneficial insects. Phytochemistry, 72(14-15), 1838-1847; Chen, C.S., Zhao, C., Wu, Z.Y., Liu, G.F., Yu, X.P., & Zhang, P.J. (2021). Whitefly-induced tomato volatiles mediate host habitat location of the parasitic wasp Encarsia formosa, and enhance its efficacy as a bio-control agent. Pest Management Science, 77(2), 749-757).

[0030] Example 1 Y-olfactometer free-choice behavior experiment

[0031] The volatile compounds were dissolved in paraffin oil to obtain an attractant with a concentration of 200 ng / μL. The attractant was placed in a slow-release device (the carrier material used was asbestos, and the mass of the asbestos was 150 mg). A Y-olfactometer was used to perform a free-choice behavior experiment to determine the selection effect of the parasitic wasp on each volatile compound. The sample group used each attractant described above, and the control group used paraffin oil. The details are as follows:

[0032] Y-olfactometer structure: Figure 1The Y-type olfactometer is shown in the figure, and the Y-type olfactometer includes a Y-type tube made of colorless transparent glass, which includes two glass arms (referred to as left arm and right arm respectively), the included angle between the two glass arms is 60°, the length of the two glass arms is 7.5 cm, and the inner diameter of the two glass arms is 2 cm. Each glass arm is sequentially connected with a flavor source glass container (specifically, the slow-release device is used as a volatile device and placed in the glass container), a distilled water bottle, an activated carbon tube, a flow meter and a gas sampling instrument; wherein one end of the Y-type olfactometer is a sample group (attractant), and the other end is a control group (paraffin oil), the Y-type olfactometer is placed in a box with a size of 80 cm x 80 cm x 50 cm, a fluorescent lamp is placed above the Y-type olfactometer, the indoor temperature is kept at 26±1℃, and the gas velocity in the tube is 300 mL / min;

[0033] Specific experimental process: based on the biological characteristics of parasitic bees (specifically female aphid parasitoid adults), the experiment is arranged between 8:30 am and 5:00 pm every day. First, assemble the Y-type olfactometer, then use the bee suction device to put the parasitic bees in the test tube into the Y-type tube, and then observe its behavioral selection response. If the parasitic bee stays in the Y-type tube for less than 5 minutes, stays more than one third of one end of the Y-type tube for more than 10 seconds, it is considered that this is the selection of the parasitic bee individual; otherwise, if the parasitic bee has no response or the response stays for less than 10 seconds within 5 minutes after being introduced, it is determined that the parasitic bee individual has no behavioral selection response, and therefore the behavioral determination experiment of the parasitic bee individual is ended. In order to reduce experimental errors, 60 female aphid parasitoid adults are used to test each attractant sample, each female aphid parasitoid adult only performs behavioral response determination once, the two arms of the Y-type tube are exchanged after every 5 female aphid parasitoid adults are determined, and a new clean Y-type tube is used to continue the determination after every 10 female aphid parasitoid adults are determined. After the experiment is completed every day, all the instruments are cleaned with alcohol with a mass fraction of 95%, and are dried for standby. The selection rate of female aphid parasitoid adults is calculated according to the following formula:

[0034] Selection rate (%) = number of female aphid parasitoid adults with selection behavior to volatile compounds / total number of female aphid parasitoid adults determined in the experiment x 100%.

[0035] Table 1 is the selection effect data of female aphid parasitoid adults to volatile compounds in Example 1, and the results show that the selection rate of female aphid parasitoid adults to citral is 2.4 times that of the control group, which is the highest in all experiments.

[0036] Table 1 is the selection effect data of female aphid parasitoid adults to volatile compounds in Example 1, and the results show that the selection rate of female aphid parasitoid adults to citral is 2.4 times that of the control group, which is the highest in all experiments.

[0037]

[0038] Example 2 Cage Free Choice Behavior Experiment

[0039] The volatile compounds were dissolved in paraffin oil to obtain an attractant with a concentration of 200 ng / μL. The attractant was placed in a slow-release device (the carrier material used was asbestos with a mass of 150 mg), and tomato plants with B. tabaci third instar nymphs and normal plants without B. tabaci third instar nymphs were placed in a cage for a free choice behavior experiment to determine the selection effect of the parasitoid (specifically female adult Encarsia) on each volatile compound. The sample group used each of the above attractants, and the control group used paraffin oil, as follows:

[0040] A cage (1 m x 1 m x 1 m) was placed in an environment with no plant odor source around the periphery, and the upper surface was provided with a 100-mesh gauze surface to facilitate ventilation and light transmission to simulate natural conditions. One slow-release device was placed at the diagonal position of the gauze cage, containing the sample group (attractant) and the control group (paraffin oil). The positions of the sample group and the control group were changed during the experiment to reduce the influence of the position on the experimental results. Encarsia adults were released in batches at the center of the cage, with 120 released each time, and allowed to move freely. The selection behavior of Encarsia adults in the cage was observed from 9:00 to 11:00 am every day until the released Encarsia adults were selected, and the next experiment was then performed. The number of times each Encarsia adult approached or stayed near the attractant or control sample was recorded during the experiment. After the experiment, the data was collected and analyzed to determine the degree of preference of Encarsia adults for different treatments. The selection rate of Encarsia adults was calculated according to the formula in Example 1.

[0041] Table 2 shows the selection effect data of Encarsia adults on volatile compounds in Example 2. The results show that the selection rate of Encarsia adults on citral was 3.02 times that of the control group, which was significantly higher than the selection rate of Encarsia adults on other volatile compounds. This again confirms that citral has high attractant activity for Encarsia adults.

[0042] Table 2 Selection of Encarsia adults on volatile compounds in Example 2 (cage experiment)

[0043]

[0044] Example 3 Y-type Olfactometer Free Choice Behavior Experiment

[0045] The citral was dissolved in paraffin oil to prepare attractants with concentrations of 2000 ng / μL, 200 ng / μL, 20 ng / μL and 2 ng / μL, respectively. Then, the free choice behavior experiment was performed to determine the selection effect of the parasitoid on each volatile compound by using the Y-type olfactometer with one end as the sample group (attractant) and the other end as the control group (paraffin oil) according to the method of Example 1.

[0046] Table 3 is the data of the influence of different concentrations of citral on the behavior selection of female adult aphidius gifuensis in Example 3. The results show that when the concentration of citral in the attractant is 20 ng / μL, 200 ng / μL and 2000 ng / μL, the selection rate of female adult aphidius gifuensis to citral is significantly higher than that of the control treatment. Especially when the final concentration of citral is 200 ng / μL, the attractivity to female adult aphidius gifuensis is the strongest, and at this time, the selection rate of aphidius gifuensis is the highest, which is 3.13 times of the control group.

[0047] Table 3 Influence of different concentrations of citral on the behavior selection of female adult aphidius gifuensis (Y-type olfactometer experiment)

[0048]

[0049] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. Use of a parasitoid attractant in attracting parasitoids for field pest biological control, the parasitoid attractant comprising an active ingredient and an organic solvent, the active ingredient being citral, the concentration of citral in the parasitoid attractant being 100-200 ng / μL; the parasitoids being Aphelinus spp.; and the pests being whiteflies.

2. Use according to claim 1, characterized in that, The organic solvent comprises one or more of paraffin oil, dichloromethane and ethanol.

3. Use according to claim 1, characterized in that, The whiteflies comprise Bemisia tabaci and / or Trialeurodes vaporariorum.

4. The use according to any one of claims 1 to 3, characterized in that, The method of field pest biological control comprises adsorbing the parasitoid attractant into a carrier material, and suspending the carrier material containing the parasitoid attractant in the field.

5. Use according to claim 4, characterized in that, The carrier material comprises a rubber head and / or a capillary tube.

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