A nerolidol-based female melon fruit fly attractant and its application

Abstract

The present invention relates to the technical field of green control of agricultural pests, and specifically to a nerolidol-based attractant for female cucurbit fruit flies and its application. The female cucurbit fruit fly attractant uses nerolidol as a single active ingredient, with an effective concentration of 0.01 mg / mL, and the solvent is selected from distilled water, dimethyl sulfoxide (DMSO) or corn oil. Experiments have shown that this concentration has a high attraction rate for female adults of cucurbit fruit flies and maintains stable activity in a high-temperature environment of 26-35°C. When used, the attractant is coated on a trapping carrier and placed in a field trapping device. The present invention is the first to utilize the specific tendency of female cucurbit fruit flies to nerolidol, a volatile substance characteristic of plant decay, to break through the resistance limitations of chemical pesticides, and has both environmental friendliness and high-temperature adaptability. It can be widely used in pest monitoring and green control in cucurbit fruit and vegetable planting areas.

Description

Technical Field

[0001] The invention belongs to the technical field of green prevention and control of agricultural pests, and particularly relates to a nerolidol-based attractant for female melon flies and applications thereof. Background Art

[0002] Melon fruit fly ( Bactrocera cucurbitae) is a global invasive pest that seriously harms cucurbit crops. Its female insects lay eggs on the fruit, directly causing devastating economic losses. The development of efficient and environmentally friendly female insect attractants is crucial for accurately monitoring the population dynamics of the cucurbit fruit fly, implementing large-scale trapping of female insects (directly reducing the amount of eggs laid), and interfering with their egg-laying behavior. It is a core requirement of integrated pest management. However, the development of attractants that are highly attractive to female cucurbit fruit flies has always faced huge challenges. The behavior of female insects is usually more focused on finding a suitable host for laying eggs rather than mating. Their olfactory response mechanism is more complex, and the sensitivity and specificity of information chemicals are extremely high. Currently, effective attractants for female melon fruit flies are extremely scarce. Both Chinese patents CN1312992C and CN100431412C provide sex attractants with ketone as the main component, which only trap and kill some male insects. Female melon fruit flies can mate repeatedly, and those that mate only once can continuously lay eggs and cause harm for up to 20 days. These male attractants can only reduce the mating rate of female melon fruit flies. Although Chinese patent CN118592448B provides a melon fruit fly female attractant, n-hexane is used as a solvent in its preparation process. N-hexane has certain volatility and toxicity. If used on a large scale in the wild, it may pollute the environment and may also cause potential harm to the health of operators. In addition, the wild environment is complex, and factors such as wind force, temperature, and humidity may affect the effect of the attractant, resulting in unstable effects in actual field applications. Existing attractant control methods (such as traps and sprays) have poor stability under extreme environmental conditions such as high temperature and high humidity, and there are phenomena such as accelerated degradation of active ingredients and shortened duration of effectiveness, which leads to a significant decrease in control efficiency (Liu Huan, Wang Yiming, Hou Jiahui, et al. Biological effects of methyl eugenol on citrus fruit fly and research progress in its control application [J]. Chinese Journal of Applied Entomology, 2023, 60(02): 475-485; Pogue T, Malod K, Weldon CW. Effects of physiological status and environmental factors on the lure responses of three pest fruit fly species (Diptera: Tephritidae). Journal of Chemical Ecology, 2024, 50(11): 679-700.). Therefore, there is no mature, efficient, simple, environmentally friendly, ecologically friendly, and non-target organism-friendly female attractant for melon fruit fly that has been widely used in the existing technology.

[0003] Insect semiochemicals, particularly plant-derived volatile organic compounds (VOCs), are considered an important source for the development of new attractants due to their environmental friendliness and potential specificity. Nerolidol is a natural sesquiterpene alcohol found widely in plants (such as citrus, tea, and melons). Existing reports indicate that nerolidol exhibits attractant activity in certain insect species. For example, Yan Zhengliang et al. found that female Holotrichia chennosaurus exhibits a negative attraction to nerolidol, while males exhibit a positive attraction (Yan Zhengliang, Liu Ling, Ma Huifen. Attraction Response of Holotrichia chennosaurus to Olive Volatiles [J]. Journal of Northeast Forestry University, 2012). Chinese patent CN112931503B discloses nerolidol as a component of a ternary mixture to attract the coleopteran leaf beetle, A. bicolor, but does not address sex specificity. Chinese patent CN118120746B discloses nerolidol as a component of a composite attractant for the octagonal leaf beetle. However, the attractant's active attractant components are composed of multiple substances, and nerolidol is not used alone as the active ingredient for attracting the octagonal leaf beetle. Its attractant effect is the result of the synergistic action of multiple components. Furthermore, the use of nerolidol in this invention patent requires the use of a specific attractant carrier, which regulates its volatilization and diffusion time to improve overall attractant efficiency and duration. It does not rely solely on nerolidol to attract the octagonal leaf beetle.

[0004] However, there is no reliable evidence or reports verifying whether nerolidol has significant attractant activity against female B. cucurbitae. This is because the insect species (Coleoptera) involved in existing research differ significantly from the B. cucurbitae of the family Tephritidae in taxonomic status, ecological habits, feeding behavior, and patterns of semiochemical utilization. Existing reports often do not strictly distinguish between the sexes of nerolidol's targets, or the reported attractant effects are primarily directed towards males or both sexes. Due to the inherent difficulty in attracting female fruit flies (especially egg-laying females), and the possible mechanism of action of nerolidol in reported insects (such as association with food or specific habitats, rather than direct action as a potent female attractant), those skilled in the art cannot consider nerolidol as a potential, highly effective attractant for female B. cucurbitae, and further research is needed.

[0005] While the biological activity of nerolidol is partially understood, the potential for developing a highly effective and specific attractant for the melon fruit fly, either as a standalone or core ingredient, and systematically evaluating its effectiveness and potential in practical application scenarios (such as field monitoring and mass trapping), has yet to be fully explored and validated in existing technologies. Exploring the unique value of nerolidol in attracting the melon fruit fly and developing novel nerolidol-based attractant products is expected to provide an innovative, environmentally friendly, and highly effective technical tool for integrated melon fruit fly management. Summary of the Invention

[0006] The purpose of the present invention is to provide a green attractant based on nerolidol, a characteristic odor substance released by melon flies during the decay of host plants, and an application method thereof, so as to solve the drug resistance and environmental problems caused by the use of existing chemical pesticides, while improving the stability of the attractant under different temperature conditions and optimizing the solvent system to adapt to field application needs.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A first aspect of the present invention provides the use of nerolidol in preparing an attractant for female melon flies, wherein the attractant contains nerolidol as the sole active ingredient at a concentration of 0.01 mg / mL.

[0009] Furthermore, the solvent in the attractant is at least one of distilled water, dimethyl sulfoxide or corn oil, preferably corn oil.

[0010] The second aspect of the present invention provides the use of the above-mentioned melon fruit fly female attractant for preparing attractant cores or attractant paper, or for use in combination with biological pesticides or low-toxic chemical pesticides to enhance the trapping ability.

[0011] The third aspect of the present invention provides a method for targeted prevention and control of female cucurbit fruit flies, wherein the above-mentioned female cucurbit fruit fly attractant is coated on a trapping carrier; the female cucurbit fruit fly attractant is used in an environment of 26-35°C.

[0012] Beneficial effects of the present invention:

[0013] (1) This invention uses the natural volatile compound nerolidol as its core ingredient, eliminating the need for chemical pesticides and thus avoiding the risk of pesticide resistance at the source. Experiments have confirmed that nerolidol at a concentration of 0.01 mg / mL can reach a peak attraction rate for female adults of the melon fruit fly. By replacing chemical poisoning with physical trapping, the amount of pesticide used can be significantly reduced.

[0014] (2) Temperature gradient experiments have shown that nerolidol maintains a good attractant effect in the range of 26°C to 35°C, significantly improving its stability at extreme temperatures compared to existing technologies. For example, the attractant rate remains at a high level in a high-temperature environment of 35°C, making it suitable for the hot summer climate in tropical and subtropical regions.

[0015] (3) Using distilled water, DMSO, corn oil and other suitable solvents, corn oil as a solvent has significant advantages over dimethyl sulfoxide and distilled water in terms of stability, environmental compatibility and practical application: Compared with DMSO, corn oil, as a natural plant oil, has no chemical toxicity and is more biodegradable, avoiding the potential risks that DMSO may pose to the health of operators and the environment. At the same time, its adhesion is better, and it can form a more stable attachment layer on the surface of the trapping carrier, reducing the loss of effective ingredients caused by environmental factors such as wind and rain; compared with distilled water, the oily properties of corn oil can significantly slow down the volatilization rate of nerolidol, extending the field duration by several times, without the need to frequently change the attractant, and in a high temperature environment of 26-35°C, the corn oil system can more stably maintain the activity of the attractant, avoiding the fluctuation of the attractant effect caused by the rapid volatilization of distilled water, and has both environmental friendliness and field practicality.

[0016] (4) For the first time, nerolidol was revealed as a key signaling molecule in the melon fruit fly's response to the odor of rotten fruit. By utilizing its natural olfactory guidance behavior, an attractant was designed, significantly improving its attractant specificity. Experiments showed that the attractant increased the attraction rate of female insects during the peak egg-laying period by more than 80% compared to the distilled water control, accurately targeting the core population of the pest. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the total ion current obtained by GC-MS technology.

[0018] Figure 2 The following are the attraction rates of different concentrations of nerolidol to adult cucurbit fruit flies. When the concentration is 0.01 mg / mL, the attraction rate to female cucurbit fruit flies is much higher than that to males, and the female attraction effect is outstanding.

[0019] Figure 3 The nerolidol attracting rate to female adults of melon fruit flies at different temperatures is shown in Table 1. It has a good attracting effect on female melon fruit flies in the temperature range of 26℃-35℃.

[0020] Figure 4 The attraction rate of different solvents, nerolidol, to female adults of melon fruit flies. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0022] Example 1 Identification of Volatiles from Rotten Zucchini

[0023] For sample analysis, 10 g of rotten zucchini sample was weighed and placed into a 20 mL headspace vial, which was then sealed. Solid-phase microextraction (SPME) was then performed using a Triplus RSH autosampler with a DVB / Carbon WR / PDMS (80 μm, 50 / 30 μm) tip. Extraction was performed at 90°C, with the sample initially shaken at 250 rpm for 5 minutes, followed by extraction for 20 minutes and a final 10-minute equilibration period. After extraction, desorption took 3 minutes, resulting in a total GC cycle time of 41 minutes.

[0024] Analysis was performed using a Thermo Fisher Scientific Trace 1610-TSQ 9610 gas chromatograph-mass spectrometer (GC-MS). Chromatographic conditions included a DB-Wax capillary column (30 m × 0.25 mm × 0.25 µm) with helium as the carrier gas at a flow rate of 1.2 mL / min and an inlet temperature of 240°C. The injection volume was 1 μL, and the split ratio was 5:1. The column oven temperature program was as follows: initial temperature 50°C, then increased to 100°C at a rate of 5°C / min, then to 150°C at a rate of 3°C / min, and finally to 240°C at a rate of 10°C / min, where it was held at 240°C for 2 minutes. Mass spectrometry conditions: an electron bombardment ionization source (EI) was used, the ion source temperature was set at 280°C, the electron energy was 70 eV, the scanning mode was full scan, and the mass scanning range was m / z 40–400.

[0025] The results are as follows Figure 1 As shown, peak 3 was identified as nerolidol, and the volatiles of rotten zucchini contained 10 volatile components.

[0026] Example 2 Experiment on the Attraction Effect of Different Concentrations of Nerolidol on Cucurbita cucurbita Adults

[0027] The nerolidol standard sample was dissolved in distilled water to prepare nerolidol solutions of 0.01 mg / mL, 0.1 mg / mL, and 1 mg / mL, respectively, as the melon fruit fly attractant treatment group; the distilled water treatment was set as the control group.

[0028] At room temperature, 500 μL of nerolidol solution and 500 μL of distilled water were evenly applied to zucchini slices approximately 1.5 cm long and 4 cm in diameter. The nerolidol-coated zucchini slices and the distilled water-coated control zucchini slices were placed at opposite ends of a foam box within a 60 cm × 60 cm × 60 cm insect cage, with a 20 cm gap between the slices. Fifty female (or male) adults of the cucurbit fruit fly (Bactrocera cucurbita) at peak egg-laying stage, 18-20 days after eclosion and starved for 6 hours, were placed into the cages. After 10 minutes, observations were made and the number of female (or male) adults of the cucurbit fruit fly (Bactrocera cucurbita) at peak egg-laying stage on each zucchini slice was recorded. Four replicates were performed for each concentration of nerolidol solution.

[0029] The experimental results are as follows Figure 2 As shown in the figure, when the concentration is 0.01 mg / mL, the attraction rate for female adults of melon fruit flies is much higher than that for males, and the attraction effect for females is outstanding.

[0030] Example 3 Experiment on the attractant effect of nerolidol at different temperatures

[0031] The 0.01 mg / mL nerolidol solution prepared in Example 2 was selected as the melon fruit fly attractant treatment group; and the distilled water treatment was set as the control group.

[0032] The indoor environment was pretreated according to the following conditions, and the indoor temperature was set to 26, 28, 30 and 35°C; the temperature parameters were maintained stable for at least 2 hours. The following experiments were carried out under each indoor temperature environment: 500 μL of nerolidol solution and distilled water were evenly applied on zucchini slices with a length of about 1.5 cm and a diameter of about 4 cm, and the zucchini slices coated with nerolidol solution and the control group zucchini slices coated with distilled water were placed at the two ends of the foam box in a 60×60×60 cm insect cage, with a distance of 20 cm between the two slices. 50 female adults of melon fruit flies in the peak egg-laying stage, which had emerged for 18-20 days and were starved for 6 hours, were introduced into an insect cage with a size of 60×60×60 cm. The results were observed after 10 minutes, and the number of female insects on the two zucchini slices was recorded respectively. The experiment was repeated 4 times for different temperature settings. The results are as follows: Figure 3 As shown, the temperature range of 26℃-35℃ has a good attracting effect on female adults in the peak egg-laying period.

[0033] Example 4 Nerolidol attractant solvent test experiment

[0034] The nerolidol standard was dissolved in distilled water, ethanol, DMSO and corn oil, and a 0.01 mg / mL nerolidol solution was prepared as the melon fruit fly attractant treatment group; the distilled water treatment was set as the control group.

[0035] At room temperature, 500 μL of melon fruit fly attractant and distilled water were evenly applied on zucchini slices about 1.5 cm long and 4 cm in diameter, respectively. The zucchini slices coated with 0.01 mg / mL nerolidol solution and the control zucchini slices coated with distilled water were placed at both ends of a foam box in a 60×60×60 cm insect cage, with a distance of 20 cm between the two slices. 50 female adults of melon fruit flies in their peak egg-laying stage, 18-20 days after eclosion and starved for 6 hours, were introduced into the 60×60×60 cm insect cage. The results were observed after 10 minutes, and the number of female insects on the two zucchini slices was recorded. The experiment was repeated 4 times for each solvent to prepare the nerolidol solution. The results are as follows: Figure 4 As shown, distilled water, DMSO and corn oil are all good solvents.

[0036] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and description. The scope of the present disclosure is not limited thereto, so as to enable those skilled in the art to utilize various exemplary embodiments of the present invention and various alternatives and modifications. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. The application of nerolidol in preparing a melon fruit fly female insect attractant, characterized in that: The attractant contains nerolidol as the only active ingredient.

2. The use according to claim 1, characterized in that The concentration of nerolidol in the attractant is 0.01 mg / mL.

3. The use according to claim 2, characterized in that: The solvent in the attractant is at least one of distilled water, dimethyl sulfoxide or corn oil.

4. The use according to claim 3, characterized in that: The solvent in the attractant is corn oil.

5. A use of a melon fruit fly female attractant, characterized in that: The attractant is used to prepare attractant cores or attractant paper, or is used in combination with biological pesticides or low-toxic chemical pesticides to enhance the trapping ability; the attractant contains nerolidol as the only active ingredient.

6. The use according to claim 5, characterized in that The concentration of nerolidol in the attractant is 0.01 mg / mL.

7. The use according to claim 6, characterized in that The solvent in the attractant is at least one of distilled water, dimethyl sulfoxide or corn oil.

8. The use according to claim 7, characterized in that The solvent in the attractant is corn oil.

9. The use according to claim 8, characterized in that The attractant is used in an environment of 26-35°C.

Images