Use of fatty acid esters in deterring oviposition by cotton bollworms

Abstract

The present invention relates to the use of fatty acid esters in deterring oviposition by cotton bollworms. In particular, the use of a combination of methyl palmitate, methyl stearate and methyl oleate in deterring oviposition by cotton bollworms.

Description

Technical Field

[0001] This invention relates to the field of biological control, and in particular to the application of methyl palmitate, methyl stearate or methyl oleate in preventing bollworm oviposition. Background Technology

[0002] The cotton bollworm (Helicoverpa armigera) is a major global agricultural pest. Its larvae have a diverse and widespread diet, damaging over 200 plant species, including major crops such as corn, cotton, and soybeans, causing severe economic losses and hindering the sustainable and healthy development of agriculture. Adults are highly migratory, and females have a strong oviposition capacity; reports indicate that a single female can lay up to 1000 eggs. Currently, the widespread cultivation of genetically modified crops has effectively controlled the large-scale damage caused by the cotton bollworm. However, in recent years, there have been reports of the bollworm developing resistance to Bt (biological toxin). Meanwhile, the use of chemical pesticides brings a series of problems such as environmental pollution and pesticide residues. Therefore, it is foreseeable that both chemical pesticides and genetically modified crops will face serious challenges and shortcomings in controlling the cotton bollworm.

[0003] Currently, widely used biological control agents in production include behavioral regulators, which mainly include sex pheromones and food attractants. However, sex pheromones only attract male insects, and food attractants have poor sensitivity. Compounds that can repel female insects from laying eggs are called oviposition inhibitors. Developing novel, green, and highly efficient pest behavioral regulators based on these can effectively reduce pest damage and has broad application prospects. Summary of the Invention

[0004] One aspect of this invention provides the application of fatty acid esters in preventing the oviposition of the cotton bollworm (Helicoverpa armigera).

[0005] In one embodiment, the fatty acid ester is at least one of palmitate, stearate and oleate; or the fatty acid ester is a combination of at least one of palmitate, stearate and oleate and linoleate.

[0006] In one specific embodiment, the palmitate is methyl palmitate, the stearate is methyl stearate, the oleate is methyl oleate, and the linoleate is methyl linoleate.

[0007] In one specific embodiment, the fatty acid ester is used to mitigate bollworm damage to target plants.

[0008] In one specific embodiment, the target plant is at least one of the following: grain, cotton, oil, melon, fruit, vegetable, flower, and medicinal plant.

[0009] In one specific embodiment, the target plant is at least one of cotton, corn, sorghum, wheat, soybean, pea, broad bean, peanut, sunflower, tomato, pepper and alfalfa.

[0010] The second invention provides an oviposition-avoiding composition comprising palmitic acid ester, stearic acid ester, and oleic acid ester.

[0011] In one specific embodiment, the palmitate is methyl palmitate, the stearate is methyl stearate, and the oleate is methyl oleate.

[0012] In one specific embodiment, the mass ratio of palmitate, stearate and oleate is 1:1:1.

[0013] In one embodiment, the oviposition-avoiding composition further includes linoleic acid esters.

[0014] In one specific embodiment, the linoleic acid ester is methyl linoleate.

[0015] In one embodiment, the spawning avoidance composition further includes linoleic acid ester, wherein the mass ratio of palmitate, stearate, oleate and linoleic acid ester is 1:1:1:1.

[0016] The third invention provides the application of the oviposition-avoiding composition according to the first invention in avoiding oviposition of the cotton bollworm (Helicoverpa armigera).

[0017] In one specific embodiment, the oviposition-avoiding composition is used to mitigate bollworm damage to target plants.

[0018] In one specific embodiment, the target plant is at least one of the following: grain, cotton, oil, melon, fruit, vegetable, flower, and medicinal plant.

[0019] In one specific embodiment, the target plant is at least one of cotton, corn, sorghum, wheat, soybean, pea, broad bean, peanut, sunflower, tomato, pepper and alfalfa.

[0020] The beneficial effects of this invention are:

[0021] This invention is the first to discover that fatty acid esters, particularly methyl palmitate, methyl stearate, and methyl oleate, can repel oviposition by the cotton bollworm (Helicoverpa armigera). Furthermore, methyl linoleate exhibits a synergistic effect with methyl palmitate, methyl stearate, and methyl oleate in repelling cotton bollworm oviposition. By applying (e.g., spraying or smearing) or placing (e.g., using devices that release the oviposition-repelling composition at intervals) the oviposition-repelling composition of this invention on the target crop, the oviposition rate of cotton bollworm on the target crop can be reduced. This not only mitigates cotton bollworm damage to the target crop but also reduces the use of chemical pesticides, thereby promoting agricultural production, agricultural product quality, and agricultural ecological safety, while effectively protecting natural enemy insects. Furthermore, based on the "push-pull" strategy, plants that attract bollworms can be planted around the target crop, or attractants (such as plant-derived attractants, sex pheromones, etc.) can be used in the surrounding non-target crop areas to kill the attracted bollworms in a concentrated manner. This can more significantly reduce the bollworm population, thereby effectively reducing the damage to the target crop and achieving the goal of green pest control. Attached Figure Description

[0022] Figure 1 An oviposition behavior box was shown to test the effect of odor compounds on the oviposition behavior of cotton bollworms.

[0023] Figure 2 The effects of tested odor compounds on the oviposition behavior of cotton bollworms were shown. Different lowercase letters indicate significant differences between different odor compounds (P<0.05), while the same letter indicates no significant differences between different tested odor compounds (P>0.05). Detailed Implementation

[0024] The present invention will be further described in detail below through preferred embodiments, but these embodiments do not constitute a limitation thereof.

[0025] Unless otherwise specified, all reagents used in the embodiments of this invention are commercially available.

[0026] Example 1

[0027] Location: The experiment was conducted in the laboratory of the Institute of Plant Protection, Chinese Academy of Agricultural Sciences;

[0028] Time: The test will be conducted from 8:00 PM to 11:00 AM the following day;

[0029] Indoor conditions: temperature 26 to 28°C, relative humidity 65±5%.

[0030] Mix methyl palmitate with the solvent n-hexane to prepare a stock solution of 100 μg / μL. Then dilute the stock solution of methyl palmitate to 1 μg / μL with n-hexane to obtain a methyl palmitate solution.

[0031] Use the oviposition behavior box as shown in Figure 1 to conduct an experiment on the effect of odor compounds on the oviposition behavior of Helicoverpa armigera. The specific operation sequence is as follows: Provide a box with an open top as shown in Figure 1 as the oviposition behavior box; Cut two pieces of clean gauze with equal size (1 / 2 of the top area of the oviposition behavior box), and then evenly moisten one of the two pieces of gauze with a size of 1 / 2 of the top area of the box with 1 mL of 1 μg / μL methyl palmitate solution to obtain a test odor gauze, and evenly moisten the other piece with 1 mL of n-hexane to obtain a n-hexane gauze. Place it for at least 1 min to allow the n-hexane on the gauze to volatilize completely; Place 3 gravid female insects in each oviposition behavior box, then first cover the open top of the box with two layers of gauze, and then place the test odor gauze and the n-hexane gauze above the two layers of gauze. Among them, the test odor gauze is placed on the test odor side, and the n-hexane gauze is placed on the other side; After 15 h, count the number of eggs laid. One oviposition behavior box is one replicate, and a total of 5 replicates are conducted.

[0032] Calculate the oviposition index based on the number of eggs laid, and then use Graphpad 9.5.1 software to draw a graph. One solid circle in the graph represents the oviposition index of one replicate, and N represents the number of replicates; Use the Paired t-test to analyze the repellent effect of the tested odor compound (methyl palmitate) on Helicoverpa armigera, and compare whether there is a significant difference between the oviposition index and 0. An oviposition index less than 0 and a significant difference from 0 indicate that the tested odor compound can significantly repel the oviposition of Helicoverpa armigera. The smaller the oviposition index, the better the repellent effect: **0.001 < P < 0.01 represents a highly significant difference; ***P < 0.001 represents an extremely highly significant difference.

[0033] Among them, the oviposition index = (T - C) / (T + C), where C represents the number of eggs laid under the control n-hexane gauze, and T represents the number of eggs laid under the test odor gauze.

[0034] The results are shown in Figure 2 .

[0035] Example 2

[0036] Replace methyl palmitate in Example 1 with methyl stearate, and the others are the same as in Example 1.

[0037] The results of the oviposition index of 5 replicates are shown in Figure 2 .

[0038] Example 3

[0039] Replace the methyl palmitate in Example 1 with methyl oleate, and the others are the same as in Example 1.

[0040] The results of the oviposition index for 5 replicates are shown in Figure 2 .

[0041] Example 4

[0042] Replace the methyl palmitate in Example 1 with methyl linoleate, and the others are the same as in Example 1.

[0043] The results of the oviposition index for 5 replicates are shown in Figure 2 .

[0044] Example 5

[0045] Replace the methyl palmitate in Example 1 with a mixture of methyl palmitate, methyl stearate and methyl oleate, where the mass ratio of methyl palmitate, methyl stearate and methyl oleate is 1:1:1, and the total concentration of the three is 3 μg / μL, thus obtaining a ternary composition solution, and the others are the same as in Example 1.

[0046] The results of the oviposition index for 5 replicates are shown in Figure 2 .

[0047] Example 6

[0048] Replace the methyl palmitate in Example 1 with a mixture of methyl palmitate, methyl stearate, methyl oleate and methyl linoleate, where the mass ratio of methyl palmitate, methyl stearate, methyl oleate and methyl linoleate is 1:1:1:1, and the total concentration of the four is 4 μg / μL, thus obtaining a quaternary composition solution, and the others are the same as in Example 1.

[0049] The results of the oviposition index for 5 replicates are shown in Figure 2 .

[0050] Result analysis

[0051] According to Figure 2 the results, it can be seen that individual methyl palmitate (***P<0.001), methyl stearate (**0.01<P<0.05) and methyl oleate (**0.01<P<0.05) all have a repellent effect on the oviposition of Helicoverpa armigera, while individual methyl linoleate has no repellent effect on the oviposition of Helicoverpa armigera (NS, P>0.05). Among them, the repellent effects of methyl palmitate and methyl stearate are comparable; the repellent effect of the ternary composition is comparable to that of methyl palmitate or methyl stearate, but the individual repellent effects of methyl palmitate and methyl stearate are significantly better than that of methyl oleate; the repellent effect of the quaternary composition is significantly better than that of the ternary composition, methyl palmitate or methyl stearate. The above results show that methyl linoleate has a synergistic effect on the repellent effect of the ternary composition.

Claims

1. An oviposition deterrent composition comprising methyl palmitate, methyl stearate, methyl oleate and methyl linoleate; the mass ratio of the methyl palmitate, methyl stearate, methyl oleate and methyl linoleate being 1:1:1:

1.

2. Use of the oviposition deterrent composition according to claim 1 for deterring oviposition of Helicoverpa armigera.

3. Use according to claim 2, characterized in that, The oviposition deterrent composition is used for mitigating damage of target plants by Helicoverpa armigera.

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