Parasitic wasp attractant and application thereof

Abstract

The invention provides a parasitic wasp attractant and application thereof, and belongs to the technical field of pest control. The parasitic wasp attractant provided by the invention comprises an active component and an organic solvent, the active component is citral, and the concentration of citral in the parasitic wasp attractant is gt; the concentration is 2ng / mu L. The citral is adopted as an active ingredient of the parasitic wasp attractant, even under the trace condition, the citral shows an efficient and stable attracting effect on parasitic wasps such as encarsia formosa, and therefore the parasitism rate and the fatality rate of field pests such as aleyrodid (specifically aleyrodid nymph) can be increased. Besides, citral is adopted as an active component, is wide in source, low in cost and environmentally friendly, does not cause harm to non-target organisms, and conforms to the development trend of modern green agriculture.

Description

Technical Field

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

[0002] Whiteflies, such as Bemisia tabaci, are globally important agricultural pests that can directly damage crops by sucking plant sap and can spread a variety of plant viruses, leading to more serious economic losses. Although traditional chemical pesticides can effectively control the whitefly population in the short term, long-term use will lead to increased pest resistance, environmental pollution, and excessive pesticide residues in agricultural products. Biological control has received increasing attention as a sustainable alternative. Among them, the use of natural enemy insects for pest control is an important part of biological control.

[0003] Encarsia formosa is a natural enemy of the genus Encarsia in the order Hymenoptera. It is an important parasitic wasp that can control whitefly pests. Encarsia formosa has now achieved large-scale breeding and commercial production, and is widely used in the integrated management of whitefly pests on greenhouse vegetables, flowers and other crops around the world. Although Encarsia formosa has been proven to be an important natural enemy of whiteflies, in actual applications, its parasitic efficiency is affected by many factors, such as environmental conditions and host density, and the control effect is usually not ideal, which limits its wide application.

[0004] The use of parasitic wasp attractants is beneficial to improving the biological control effect of parasitic wasps on field pests. For the Aphididae, the plant volatile components myrcene and caryophyllene have been shown to have certain attractant activity to the parasitic wasp, but the attractant effect on the parasitic wasp still needs to be improved. Summary of the invention

[0005] The purpose of the present invention is to provide a parasitic wasp attractant and application thereof. The parasitic wasp attractant provided by the present invention has an excellent attracting effect on parasitic wasps such as Entomophthora ensiformis.

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

[0007] The invention 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.

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

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

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

[0011] The present invention provides the use of the parasitic wasp attractant described in the above technical solution in attracting parasitic wasps to carry out biological control of field pests.

[0012] Preferably, the parasitic wasp includes Entomophilus ensiformis.

[0013] Preferably, the pests include whiteflies.

[0014] Preferably, the whiteflies include Bemisia tabaci and / or Trichoderma tabaci.

[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 the field.

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

[0017] The present invention 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. The present invention has discovered a plant-derived volatile compound that has an excellent attractant effect on aphid wasps, namely citral (C 10 H 16 O), which is also called citronellal or 3,7-dimethyl-2,6-octadienal, is a naturally occurring monoterpenoid compound with a strong lemon scent. It is used as an active ingredient of a parasitic bee attractant. Even under trace conditions, citral also shows an efficient and stable attracting effect on parasitic bees such as Aphididae, thereby facilitating the improvement of the parasitism rate and mortality rate of field pests such as whiteflies (specifically, whitefly nymphs). In addition, the present invention uses citral as an active ingredient, which is not only widely available and low in cost, but also environmentally friendly, and will not cause harm to non-target organisms, which is in line with the development trend of modern green agriculture. The results of the embodiment show that the present invention proves that citral has good attractant activity to Aphididae, and is suitable as an active ingredient of the parasitic bee attractant, by Y-type olfactometer free choice behavior experiment, caged free choice behavior experiment and key volatiles (i.e., active ingredient citral) different concentration selectivity experiments, compared with 8 volatile compounds such as β-ocimene, 3-hexenal, methyl salicylate, 3-carene, caryophyllene, α-phellandrene, humulene and β-myrcene. At the same time, the present invention adopts citral as an active ingredient, which can significantly enhance the foraging activity of Aphididae at a relatively low concentration, improve its ability to locate and parasitize whitefly nymphs, and improve the parasitic bee field parasitism rate, so as to achieve the effect of parasitic bees efficiently controlling field pests. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the Y-type olfactometer used in the embodiment of the present invention. DETAILED DESCRIPTION

[0019] The invention 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.

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

[0021] As an embodiment of the present invention, the concentration of citral in the parasitic wasp attractant can be 20-2000 ng / μL, specifically 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 invention, the organic solvent may include one or more of paraffin oil, dichloromethane and ethanol, specifically paraffin oil, dichloromethane or ethanol.

[0023] The present invention has no special limitation on the preparation method of the parasitic wasp attractant, and the active ingredients can be directly dissolved in an organic solvent.

[0024] The present invention provides the use of the parasitic wasp attractant described in the above technical solution in attracting parasitic wasps for biological control of field pests. The present invention adopts citral as a volatile attractant, which is a natural product present in plants, has the characteristics of low toxicity and easy degradation, and is friendly and safe to humans, animals and the ecological environment. Compared with the existing pest attractants on the market, the parasitic wasp attractant provided by the present invention is aimed at attracting beneficial insects and parasitic wasps, eliminating the worry of growers about attracting more pests to their fields. The more beneficial insects there are, the better the field control effect is. It is applied to the biological control of field pests, and through the attracting effect on parasitic wasps, the parasitism rate of parasitic wasps on field pests is increased, and the effect of parasitic wasps controlling field pests is achieved.

[0025] As an embodiment of the present invention, the parasitic wasp may specifically include aphid wasp, which may be a female aphid wasp, and the female aphid wasp may specifically be a female adult aphid wasp; the pest may specifically include whitefly, which may include Bemisia tabaci and / or greenhouse whitefly, and the whitefly may specifically be a Bemisia tabaci nymph and / or a greenhouse whitefly nymph.

[0026] As an embodiment of the present invention, the method for biological control of field pests may include: adsorbing the parasitic bee attractant into a carrier material, and hanging the carrier material containing the parasitic bee attractant in the field; the carrier material may include a rubber head and / or a capillary tube. In the embodiment of the present invention, asbestos is specifically used as a carrier material to verify the attracting effect of the parasitic bee attractant of the present invention. The present invention does not specifically limit the adsorption method and the amount of the parasitic bee attractant and the carrier material. Specifically, the carrier material can be immersed in the parasitic bee attractant, and it is ensured that the parasitic bee attractant is fully adsorbed on the carrier material. As an embodiment of the present invention, the carrier material adsorbed with the parasitic bee attractant can be placed in a slow-release device, and the field pest biological control can be carried out by releasing the entomophilus fasciatus at the same time; the slow-release device can specifically be an air-permeable but liquid-impermeable slow-release device. The present invention does not specifically limit the specific type and structure of the slow-release device.

[0027] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0029] The slow-release device used in the following experiments is permeable to air but not to liquid. For details, please refer to the slow-release volatile dispenser in the literature (von Mérey, G., Veyrat, N., Mahuku, G., Valdez, RL, Turlings, TC, & 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, CS, Zhao, C., Wu, ZY, Liu, GF, Yu, XP, & Zhang, PJ (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 ManagementScience,77(2),749-757).

[0030] Example 1 Y-type 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, and 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 free choice behavior experiment was conducted using a Y-type olfactometer to determine the selection effect of the aphid wasp on each volatile compound, wherein the sample group used the above attractants and the control group used paraffin oil, as follows:

[0032] Y-type olfactometer structure: Figure 1is a schematic diagram of the Y-type olfactometer, wherein the Y-type olfactometer comprises a Y-type tube, the material of the Y-type tube is colorless transparent glass, and the Y-type tube comprises two glass arms (respectively denoted as the left arm and the right arm), the angle between the two glass arms is 60°, the length of the two glass arms is 7.5 cm, the inner diameter of the two glass arms is 2 cm, and each glass arm is sequentially connected to a flavor source glassware (specifically, a slow-release device is used as a volatile device and is placed in the glassware), a distilled water bottle, an activated carbon tube, a flow meter and a gas sampler; wherein one end of the Y-type olfactometer is a sample group (attractant), and the other end is a control group (paraffin oil), and the Y-type olfactometer is placed in a box with a size of 80 cm×80 cm×50 cm as a whole, and a fluorescent lamp is placed above the Y-type olfactometer, the indoor temperature is maintained at 26±1°C, and the gas velocity in the tube is 300 mL / min;

[0033] Specific experimental process: Based on the biological characteristics of parasitic wasps (specifically, adult female Aphididae), this experiment was scheduled to be carried out between 8:30 am and 5:00 pm every day. First, assemble the Y-shaped olfactometer, then use a bee sucker to put the parasitic wasps in the test tube into the Y-shaped tube, and then observe its behavioral selection response. If the parasitic wasp stays in the Y-shaped tube within 5 minutes, exceeds one-third of one end of the two arms, and stays for more than 10 seconds, it is considered that this is a choice of the individual parasitic wasp; on the contrary, within 5 minutes, if the parasitic wasp has no reaction after being introduced and released or the reaction stay time is less than 10 seconds, it is determined that the individual parasitic wasp has no behavioral selection response, so the judgment experiment on the behavior of the individual parasitic wasp will end. In order to reduce experimental errors, each attractant sample was tested with 60 female adult Aphididae. Each female adult Aphididae was only tested once for behavioral response. After every 5 female adults were tested, the two arms of the Y-shaped tube were swapped. After every 10 female adults were tested, a new clean Y-shaped tube was used to reconnect and continue the test. After the experiment was completed every day, all instruments were wiped with 95% alcohol and dried for use. The selection rate of female adults of Aphididae was calculated according to the following formula:

[0034] Selection rate (%) = number of female adults of Entomophthora ensifolia that have selection behavior for volatile compounds / total number of female adults of Entomophthora ensifolia measured in the experiment × 100%.

[0035] Table 1 shows the selection effect data of female adults of Entomophthora ensiformis on volatile compounds in Example 1. The results show that the selection rate of female adults of Entomophthora ensiformis on citral is 2.4 times that of the control group, which is the highest selection rate in all experiments.

[0036] Table 1 Selectivity of female adults of Entomophthora ensiformis for volatile compounds in Example 1 (Y-type olfactometer test)

[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, and the attractant was placed in a slow-release device (the carrier material used was asbestos, and the mass of the asbestos was 150 mg). Tomato plants with third-instar nymphs of Bemisia tabaci and normal plants without third-instar nymphs of Bemisia tabaci were placed in a cage to conduct a free choice behavior experiment to determine the selection effect of Encarsia fasciatus (specifically, female Encarsia fasciatus adults) on each volatile compound, wherein the sample group used the above attractants, and the control group used paraffin oil, as follows:

[0040] A cage (1m×1m×1m) was placed in an environment without plant odor sources around it, and its upper surface was set to a 100-mesh gauze surface to facilitate ventilation and light transmission to simulate natural conditions; a slow-release device was placed at the diagonal position of the cage, including a sample group (attractant) and a control group (paraffin oil), and 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; the adult Aphididae wasps were released in batches at the center of the cage, 120 heads were released each time, and they were allowed to move freely; the selection behavior of the Aphididae wasps adults in the cage was observed from 9:00 to 11:00 am every day until the released Aphididae wasps adults were selected, and then the next group of experiments were carried out; during the experiment, the number of times each Aphididae wasps adult approached or stayed near the attractant or control sample was recorded; after the experiment, data was collected and the degree of selective preference of Aphididae wasps adults for different treatments was analyzed. The selection rate of Aphididae wasps adults was calculated with reference to the formula in Example 1.

[0041] Table 2 shows the selection effect data of the adults of the Aphididae on volatile compounds in Example 2. The results show that the selection rate of the adults of the Aphididae to citral is 3.02 times that of the control group, which is significantly higher than the selection rate of the adults of the Aphididae to other volatile compounds, once again confirming that citral has a high attractant activity to the adults of the Aphididae.

[0042] Table 2 Selectivity of adults of Aphididae to volatile compounds in Example 2 (cage experiment)

[0043]

[0044] Example 3 Y-type olfactometer free choice behavior experiment

[0045] 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, referring to the method in Example 1, a free choice behavior experiment was carried out using a Y-type olfactometer to determine the selection effect of the aphid wasp on each volatile compound, wherein one end of the Y-type olfactometer was a sample group (attractant) and the other end was a control group (paraffin oil).

[0046] Table 3 shows the effect of different concentrations of citral on the behavioral selection of female adult Capsicum fasciatum 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 Capsicum fasciatum to citral is significantly higher than that of the control treatment, especially when the final concentration of citral is 200 ng / μL, the attractant activity for female adult Capsicum fasciatum is the strongest, and the selection rate of Capsicum fasciatum to it is the highest, which is 3.13 times that of the control group.

[0047] Table 3 Effects of different concentrations of citral on the behavioral choices of female adults of the aphid fly (Y-type olfactometer experiment)

[0048]

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. 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 >2 ng / μL.

2. The parasitic wasp attractant according to claim 1, characterized in that The concentration of citral in the parasitic wasp attractant is 20-2000 ng / μL.

3. The parasitic wasp attractant according to claim 2, characterized in that The concentration of citral in the parasitic wasp attractant is 100-200 ng / μL.

4. The parasitic wasp attractant according to any one of claims 1 to 3, characterized in that The organic solvent includes one or more of paraffin oil, dichloromethane and ethanol.

5. Use of the parasitic wasp attractant according to any one of claims 1 to 4 in attracting parasitic wasps for biological control of field pests.

6. The use according to claim 5, characterized in that: The parasitic wasps include Entamoeba fasciatus.

7. The use according to claim 6, characterized in that: The pests include whiteflies.

8. The use according to claim 7, characterized in that: The whiteflies include Bemisia tabaci and / or greenhouse whitefly.

9. The use according to any one of claims 5 to 8, characterized in that: 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 the field.

10. The use according to claim 9, characterized in that: The carrier material includes a rubber head and / or a capillary tube.

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