Use of rebaudioside in deterring oviposition by fruit flies

Abstract

This invention discloses the application of stevia in repelling egg-laying in fruit flies. The sweetener stevia selected by this invention exhibits good egg-laying repellency against the citrus fruit fly, melon fruit fly, and pumpkin fruit fly. Stevia is readily available in actual production, causes no environmental pollution, and can be applied to the control of fruit fly pests.

Description

Technical Field

[0001] This invention belongs to the field of pest control technology, specifically relating to the application of betaine in repelling fruit fly oviposition. Background Technology

[0002] The orchid fruit fly ( Bactrocera dorsalis The oriental fruit fly (Hendel) is a global quarantine pest that poses a serious threat to the fruit industry in tropical and subtropical regions due to its high reproductive rate and wide host range. Female oriental fruit flies lay eggs inside the fruit, and the larvae bore into the fruit, damaging it and causing rot or fruit drop, rendering the fruit economically worthless. Because the larvae live inside the fruit, the damage is concealed. Generally, by the time the eggs and larvae are found inside the fruit, it is too late to save the fruit. This unique developmental process of the oriental fruit fly makes it difficult to control, posing significant challenges to pest management. Developing oviposition repellency techniques targeting the relatively exposed adult stage is crucial for controlling this pest. Currently, there are many limitations to oriental fruit fly control methods. The extensive use of chemical pesticides not only easily leads to pesticide resistance in oriental fruit flies but also causes environmental pollution; existing physical and biological control methods also need improvement in terms of targeting and effectiveness. Developing oviposition repellency techniques targeting adult insects is a key breakthrough in controlling this pest. Summary of the Invention

[0003] In order to overcome the shortcomings and disadvantages of the prior art, the purpose of this invention is to provide the application of betaine in repelling fruit fly oviposition.

[0004] In preliminary indoor bioassays, it was found that the oriental fruit fly laid fewer eggs on fruits treated with the natural sweetener stevia. Observations revealed that when oriental fruit flies came into contact with stevia, they would noticeably extend their proboscis, and their labial flaps are the primary organ for taste recognition. Further experiments showed that the electrophysiological response of oriental fruit flies to stevia increased with increasing stevia concentration, indicating a dose-dependent oviposition-repelling effect of stevia on oriental fruit flies. Furthermore, stevia also exhibited significant oviposition-repelling effects on the melon fruit fly and the pumpkin fruit fly.

[0005] The first objective of this invention is to provide the application of betaine in the control of fruit flies.

[0006] Preferably, the application is the use of betaine in repelling fruit flies.

[0007] Preferably, the application is the use of betaine in repelling fruit fly oviposition.

[0008] Preferably, the application is the use of betaine in repelling fruit flies from feeding.

[0009] Preferably, the fruit fly is the oriental fruit fly (Bactrocera dorsalis). Bactrocera dorsalis Hendel), melon fly ( Bactrocera cucurbitae(Coquillett) and / or pumpkin fruit fly ( Bactrocera tau (Walker)

[0010] A second objective of this invention is to provide the application of betaine in the preparation of fruit fly repellents.

[0011] Preferably, the concentration of betaine in the fruit fly repellent is 2.5 × 10⁻⁶. -3 Concentrations of mM or higher can be used. For example, concentrations can be 0.25 mM, 25 mM, or 2% by mass.

[0012] Preferably, the fruit fly is the orange fruit fly, the melon fruit fly, and / or the pumpkin fruit fly.

[0013] A third objective of this invention is to provide a method for repelling fruit flies from laying eggs, comprising the step of using betaine or the aforementioned fruit fly repellent.

[0014] Preferably, the fruit fly is the orange fruit fly, the melon fruit fly, and / or the pumpkin fruit fly.

[0015] The present invention has the following advantages and beneficial effects compared with the prior art:

[0016] (1) The present invention screened out a sweetener that has a good oviposition repellent effect on the oriental fruit fly from different sweeteners and found that it is stevia glycoside.

[0017] (2) The sweeteners screened by this invention are easy to obtain in actual production, can be used as food additives, have no environmental pollution, and can be applied to the control of oriental fruit flies.

[0018] (3) The sweetener stevia glycosides screened in this invention also have a good repellent effect on the control of other harmful fruit flies (such as melon fruit fly and pumpkin fruit fly), and have a very broad application prospect. Attached Figure Description

[0019] Figure 1 This is a graph showing the results of different sweeteners in repelling oviposition in the oriental fruit fly.

[0020] Figure 2 This is a graph showing the results of the analysis of the taste stimulation effect of stevia on orientalis.

[0021] Figure 3 This is a dose-response analysis chart of the effect of betaine on oviposition repellency in fruit flies.

[0022] Figure 4 This is a graph showing the results of the analysis of the oviposition repellency of different fruit flies by betaine. Detailed Implementation

[0023] The following embodiments are further illustrations of the present invention, but not limitations thereof.

[0024] Product information for the sweeteners and bittereners used in the following examples is shown in Table 1.

[0025] Table 1 Information on tested sweeteners and bittereners

[0026]

[0027] Example 1: Comparison of the repellent effects of different sweeteners on oviposition of the oriental fruit fly.

[0028] Preparation of test solutions: The test solutions are aqueous solutions of sweeteners or bittering agents. The aqueous solutions of sweeteners are 2% (w / w) of lactitol, sorbitol, erythritol, xylitol, 1% glycyrrhizic acid, 2% mogroside, 2% steviol glycoside, 2% stevioside, 2% cyclamate, 2% sodium saccharin, or 2% sucralose. The aqueous solution of bittering agents is 0.5% (w / w) of denatum. Because a 2% (w / w) concentration of stevioside was selected as the test concentration in a preliminary oviposition and repellency experiment, the concentrations of other sweeteners were standardized based on stevioside. Since glycyrrhizic acid is difficult to dissolve at high concentrations and forms a gel, a 1% (w / w) concentration was used.

[0029] Ten randomly selected 16-day-old sexually mature female oriental fruit flies (the insect source was from the Insect Ecology Research Laboratory of South China Agricultural University) were placed in cylindrical plastic rearing cages as one replicate. Pumpkins were cut into 2 cm × 4 cm × 1 cm pieces, soaked in the test solution for 10 min, then removed and placed in the plastic rearing cages for oriental fruit flies to lay eggs for 2 h. The pumpkin pieces were then dissected to check the number of eggs in the flesh. The control for each treatment was achieved by replacing the test solution with water. Eight replicates were set up for each treatment.

[0030] The test results are as follows:

[0031] Figure 1 The results showed that sweeteners and bittering agents, including stevia glycosides, exhibited significant oviposition-repelling effects on *Bacteroides citrinum*, with stevia glycosides showing the most pronounced effect and the largest effect value. Furthermore, *Bacteroides citrinum* briefly hovered on pumpkin fruit pieces treated with stevia glycosides before flying away immediately, without being observed to feed or lay eggs. This indicates that stevia glycosides have significant feeding and oviposition-repelling effects on *Bacteroides citrinum*.

[0032] Example 2: Taste stimulation of citrus fruit flies by betaine

[0033] To evaluate the taste stimulation effect of stevia on *Bacteroides citrinum*, a single-sensor recorder was used to study the stimulation response of the labial sensilla of *Bacteroides citrinum* in the presence of stevia. Pure water was used as the solvent and control, and stevia was prepared at concentration gradients of 2.5 × 10⁻⁶. -7 mM, 2.5×10-5 mM, 2.5×10 -3 mM, 2.5×10 -1 Solutions of 25 mM and 25 mM were prepared. Oriental fruit flies were fixed under a microscope, and their hair-like sensilla were stimulated with different concentrations of betaine. Electrophysiological responses were recorded using a single-sensor recorder. Each concentration gradient was repeated at least 10 times.

[0034] The test results are as follows:

[0035] The electrophysiological responses of oriental fruit flies stimulated with different concentrations of betaine are as follows: Figure 2 As shown. The orange fruit fly hair-type sensor corresponds to 2.5 × 10⁻⁶. -3 mM, 2.5×10 -1 The electrophysiological response frequencies of mM and 25 mM stevia solutions were significantly higher than those of pure water, and the response frequencies increased with increasing stevia concentration.

[0036] Example 3: Dose-effect relationship of betaine on oviposition repellency in oriental fruit fly

[0037] To evaluate the dose-response effect, this embodiment selected different concentrations (concentration gradient of 2.5 × 10⁻⁶). -7 mM, 2.5×10 -5 mM, 2.5×10 -3 mM, 2.5×10 -1 Pumpkin was prepared with 25 mM and 25 mM solutions of betaine. Pumpkin pieces were cut into equal sizes (2 cm × 4 cm × 1 cm) and soaked in betaine solutions of different concentrations, using pure water as a solvent and control. The treated pumpkin pieces were then labeled and placed in a plastic rearing cage containing 10 sexually mature female oriental fruit flies for 2 hours. Eggs were collected and counted after 2 hours. Eight replicates were set up.

[0038] The test results are as follows:

[0039] The oviposition repellency effect of different concentrations of stevioside on oriental fruit fly was tested. Figure 3 The results showed that this natural sweetener had a dose-dependent effect on the oviposition repellency of the oriental fruit fly. Specifically, as the concentration of succinoside increased, the number of eggs laid by the oriental fruit fly gradually decreased, and the oviposition repellency effect became more pronounced.

[0040] Example 4: Repellent effect of betaine on oviposition of different fruit flies

[0041] Ten sexually mature melon flies were randomly selected. Bactrocera cucurbitae (Coquillett) female and 10 sexually mature pumpkin fruit flies ( Bactrocera tauFemale fruit flies (sourced from the Insect Ecology Laboratory of South China Agricultural University) were placed in different cylindrical plastic rearing cages, serving as one replicate. Pumpkin pulp was cut into 2 cm × 4 cm × 1 cm pieces, soaked in a 2% (w / w) sucralose aqueous solution for 10 min, then placed in the plastic rearing cages for fruit flies to lay eggs for 2 h. The pumpkin pieces were then dissected to check the number of eggs in the pulp. The control in each treatment was achieved by replacing the 2% (w / w) sucralose aqueous solution with water. Each treatment had 8 replicates.

[0042] The test results are as follows:

[0043] Figure 4 The results showed that stevia glycosides exhibited significant oviposition-repelling effects on both melon fruit fly and pumpkin fruit fly.

Claims

1. Application of betaine in repelling fruit flies, wherein the fruit fly is *Bactrocera dorsalis*. Bactrocera dorsalis Hendel, melon fly Bactrocera cucurbitae (Coquillett) or pumpkin fruit fly Bactrocera tau (Walker).

2. The application according to claim 1, characterized in that, The application of betaine in repelling fruit fly oviposition.

3. The application according to claim 1, characterized in that, This study investigates the application of betaine in repelling fruit flies from feeding.

4. Application of betaine in the preparation of fruit fly repellent, wherein the fruit fly is the oriental fruit fly, melon fruit fly, or pumpkin fruit fly.

5. The application according to claim 4, characterized in that, The concentration of betaine in the fruit fly repellent is 2.5 × 10⁻⁶. -3 mM or more.

6. A method for repelling fruit flies from laying eggs, characterized in that, The method includes the step of repelling the fruit flies using betaine or the fruit fly repellent described in claim 5, wherein the fruit flies are oriental fruit flies, melon fruit flies, or pumpkin fruit flies.

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