Method for evaluating damage of spodoptera frugiperda to corn ears

Abstract

The invention discloses a method for evaluating damage of spodoptera frugiperda to corn ears, and belongs to the technical field of ecological prevention and control of harmful insects. The invention provides a new method for judging the damage degree of the grassland spodoptera frugiperda to the corn ear by measuring the bending angle of the corn ear for the first time, and the method specifically comprises the following steps: selecting the corn damaged by the grassland spodoptera frugiperda in the milk-ripe stage of the corn, measuring the bending angle of the corn ear, and evaluating the corn yield damage condition according to the bending angle of the corn ear. According to the method, the damage degree of the corn ear can be efficiently, quickly and objectively judged, the problems of high area measurement difficulty, large error and the like caused by irregular damaged parts of the corn ear in the existing evaluation method are solved, a scientific basis is provided for evaluating the insect resistance of the transgenic corn, and the method is suitable for large-scale popularization and application. The method is of great significance for perfecting a grassland spodoptera frugiperda prevention and control

Description

Technical Field

[0001] The present invention relates to the technical field of ecological control of harmful insects, and in particular to a method for evaluating the damage of fall armyworm to corn ears. Background Art

[0002] Corn, as an important food crop, serves as a link between agriculture and animal husbandry. During its growth, corn is attacked by pests, resulting in reduced yields. The fall armyworm, native to tropical and subtropical regions of America, is one of the most serious pests damaging corn growth. The fall armyworm is an omnivorous pest that feeds on young leaves, filaments, and kernels of corn. During the seedling and ear stages, it gathers on corn leaves and ears to feed, directly causing yield losses. Its granular excrement, mixed with the kernels, can also aggravate plant diseases and significantly reduce corn quality.

[0003] Currently, genetically modified insect-resistant corn is the most effective method for controlling the fall armyworm. It not only reduces pesticide use but also minimizes labor costs, making it the optimal long-term control strategy. Before approval for planting, genetically modified insect-resistant corn undergoes a comprehensive environmental safety assessment, primarily encompassing resistance evaluation (herbicide tolerance and insect resistance), viability, exogenous gene flow, and biodiversity impacts. However, the published environmental safety assessment standards for genetically modified insect-resistant corn only cover insect resistance evaluation for the Asian corn borer, cotton bollworm, and armyworm, while comprehensive resistance evaluation for the fall armyworm has yet to be established.

[0004] Since evaluation of fall armyworm resistance has yet to be established, current methods typically draw on those used for lepidopteran pests such as the corn borer, primarily based on the extent of damage to corn leaves. However, the extent of corn leaf damage alone cannot accurately reflect the actual impact of fall armyworm on corn cobs. Furthermore, since fall armyworm primarily infests corn cobs, and the affected cobs are located in irregular areas, area measurement is difficult and subject to significant error, making it difficult to accurately assess the actual impact of fall armyworm on corn yields. Therefore, establishing a scientific and systematic evaluation system for fall armyworm resistance is a pressing issue. This will not only help objectively and efficiently assess the actual effects of genetically modified insect-resistant corn, but will also provide an important basis for the development and promotion of subsequent varieties. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for evaluating the damage caused by fall armyworm to corn ears, so as to solve the problems existing in the above-mentioned prior art. The present invention proposes for the first time a new method for quickly, simply and intuitively judging the degree of damage caused by fall armyworm to corn ears by measuring the bending angle of corn ears. This method can not only efficiently and quickly objectively judge the degree of damage to corn ears, but also solves the problems of the existing evaluation methods such as the high difficulty in measuring the area and large errors caused by the irregularity of the damaged parts of the corn ears. This method provides a scientific basis for the evaluation of the insect resistance of transgenic corn and is of great significance to the improvement of the technical system for the prevention and control of fall armyworm.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides an application of the bending angle of a corn ear in evaluating the impact of fall armyworm infestation on corn yield.

[0008] Optionally, the method for measuring the bending angle of the corn ear is as follows:

[0009] Take the insect-infested surface of the corn cob as the front, and measure the angle of the corn cob formed by insect damage on the section perpendicular to the front; when measuring, take the deepest part of the insect-infested area as the vertex, draw a line parallel to the edge of the lower half of the cob on one side, and draw a straight line extending outward along the damaged outline of the section on the other side. The angle formed by the vertex and the two straight lines is recorded as the bending angle of the corn cob.

[0010] The present invention also provides a method for evaluating the impact of fall armyworm damage on corn yield, comprising the following steps:

[0011] During the milky stage of corn, corn infested by fall armyworm was selected, the bending angle of the corn cobs was measured, and the damage to corn yield was evaluated based on the bending angle of the corn cobs.

[0012] Optionally, the method for measuring the bending angle of corn ears is as follows:

[0013] Take the insect-infested surface of the corn cob as the front, and measure the angle of the corn cob formed by insect damage on the section perpendicular to the front; when measuring, take the deepest part of the insect-infested area as the vertex, draw a line parallel to the edge of the lower half of the cob on one side, and draw a straight line extending outward along the damaged outline of the section on the other side. The angle formed by the vertex and the two straight lines is recorded as the bending angle of the corn cob.

[0014] Optionally, the assessment of corn yield damage includes an assessment of the extent of damage to corn ears and an assessment of the level of damage to corn yield caused by fall armyworm.

[0015] Optionally, when the bending angle of the corn cob is less than 145°, the corn cob is severely damaged; when the bending angle of the corn cob is within the range of 145-150°, the corn cob is severely damaged; when the bending angle of the corn cob is within the range of 150-155°, the corn cob is moderately damaged; when the bending angle of the corn cob is within the range of 155-170°, the corn cob is slightly damaged; when the bending angle of the corn cob is within the range of 170-180°, the corn cob is not damaged.

[0016] Optionally, the method for determining the level of harm is as follows: when the bending angle of the corn cob is less than 145°, the harm level of the fall armyworm to the corn yield is level 9; when the bending angle of the corn cob is within the range of 145-150°, the harm level of the fall armyworm to the corn yield is level 7; when the bending angle of the corn cob is within the range of 150-155°, the harm level of the fall armyworm to the corn yield is level 5; when the bending angle of the corn cob is within the range of 155-170°, the harm level of the fall armyworm to the corn yield is level 3; when the bending angle of the corn cob is within the range of 170-180°, the harm level of the fall armyworm to the corn yield is level 1.

[0017] The present invention also provides application of the evaluation method in evaluating the resistance of transgenic insect-resistant corn.

[0018] Optionally, the resistance evaluation includes resistance evaluation to Spodoptera frugiperda.

[0019] The present invention discloses the following technical effects:

[0020] This invention proposes a novel method for quickly, easily, and intuitively determining the extent of fall armyworm damage to corn ears by measuring the bend angle of corn ears. Artificial inoculation experiments confirm that the smaller the bend angle of the corn ear, the greater the damage. Compared with existing methods, this method not only efficiently and quickly objectively determines the extent of corn ear damage, but also addresses existing evaluation methods' issues of difficulty in measuring area and large errors caused by the irregularity of damaged areas.

[0021] The evaluation method provided by the present invention can efficiently and simply evaluate the impact of fall armyworm on the economic yield of corn, provide a scientific basis for the evaluation of insect-resistant transgenic corn, and is of great significance to improving the technical system for the prevention and control of fall armyworm. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a schematic diagram of measuring the bending angle of corn ears;

[0024] Figure 2 Numbers 1-3 represent variety 1; numbers 4-6 represent variety 2; numbers 1, 2, 4, and 5 represent fruit ears damaged by fall armyworm; numbers 3 and 6 represent normal fruit ears; the scale in the figure is 10 cm. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] Two selected in the embodiment of the present invention

[0031] Corn varieties, corn variety 1 is Xinda 913, corn variety 2 is Guidan 162, and the above two corn varieties were purchased from Guangzhou Seed Business Department, Tianhe District, Guangzhou City, Guangdong Province.

[0032] Example

[0033] 1. Corn planting

[0034] Two different corn varieties (corn variety 1 and corn variety 2) were selected for sowing. Conventional management was carried out after corn sowing, and insect inoculation was carried out during the silking stage of corn. 40 corn plants of each variety were inoculated.

[0035] 2. Artificial inoculation

[0036] When the filaments are pulled out 2-3 cm, use a brush to attach the larvae of the fall armyworm to the filaments, with 30 larvae attached to each plant.

[0037] 3. Investigation Records

[0038] 50-60 days after inoculation, when the corn ears enter the milky stage, investigate the damage to the corn leaves and measure the bending angle of the ears. The measurement method is as follows:

[0039] Select corn ears damaged by fall armyworms and measure the angle of the corn ear damaged by insects on a cross section perpendicular to the front, with the insect-infested surface as the front. When measuring, take the deepest part of the insect-infested area as the vertex, draw a line parallel to the edge of the lower half of the ear on one side, and draw a straight line extending outward along the damaged outline of the cross section on the other side. The angle formed by the vertex and the two straight lines is recorded as the bending angle of the corn ear, such as Figure 1 shown.

[0040] 4. Data statistical processing

[0041] The measured data of corn ear bending angles were statistically analyzed to calculate the corn ear damage rate. The calculation method is as follows:

[0042] Damage rate of corn ears = number of damaged corn ears / total number of corn ears × 100%.

[0043] The statistical results of corn ear bending angle and corn ear damage rate are shown in Table 1. The phenotype of some damaged ears is shown in Figure 2 shown.

[0044] Table 1 Corn ear bending angle and corn ear damage rate

[0045]

[0046]

[0047] As can be seen from the data in Table 1, as a whole, the corn ear damage rate shows an upward trend as the corn ear bending angle decreases. That is, the smaller the measured corn ear bending angle, the greater the degree of corn ear damage. When the corn ear bending angle is less than 145°, the corn ear is severely damaged; when the corn ear bending angle is within the range of 145-150°, the corn ear is severely damaged; when the corn ear bending angle is within the range of 150-155°, the corn ear is moderately damaged; when the corn ear bending angle is within the range of 155-170°, the corn ear is slightly damaged; and when the corn ear bending angle is within the range of 170-180°, the corn ear is essentially undamaged.

[0048] Based on the above data and results, the corn yield damage level was divided according to the bending angle caused by the fall armyworm damage to corn ears. The classification basis is shown in Table 2.

[0049] Table 2 Grading standards for the degree of damage to corn yield caused by fall armyworm

[0050]

[0051] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. Application of corn ear bending angle in evaluating the impact of fall armyworm infestation on corn yield.

2. The use according to claim 1, characterized in that The method for measuring the bending angle of the corn ear is as follows: Take the insect-infested surface of the corn cob as the front, and measure the angle of the corn cob formed by insect damage on the section perpendicular to the front; when measuring, take the deepest part of the insect-infested area as the vertex, draw a line parallel to the edge of the lower half of the cob on one side, and draw a straight line extending outward along the damaged outline of the section on the other side. The angle formed by the vertex and the two straight lines is recorded as the bending angle of the corn cob.

3. A method for evaluating the impact of fall armyworm damage on corn yield, characterized in that: The following steps are involved: During the milky stage of corn, corn infested by fall armyworm was selected, the bending angle of the corn cobs was measured, and the damage to corn yield was evaluated based on the bending angle of the corn cobs.

4. The evaluation method according to claim 3, wherein: The method for measuring the bending angle of corn ears is as follows: Take the insect-infested surface of the corn cob as the front, and measure the angle of the corn cob formed by insect damage on the section perpendicular to the front; when measuring, take the deepest part of the insect-infested area as the vertex, draw a line parallel to the edge of the lower half of the cob on one side, and draw a straight line extending outward along the damaged outline of the section on the other side. The angle formed by the vertex and the two straight lines is recorded as the bending angle of the corn cob.

5. The evaluation method according to claim 3, wherein: The assessment of corn yield damage includes the assessment of the degree of damage to corn ears and the assessment of the level of damage caused by the fall armyworm to corn yield.

6. The evaluation method according to claim 3, wherein: When the bending angle of the corn cob is less than 145°, the corn cob is severely damaged; when the bending angle of the corn cob is within the range of 145-150°, the corn cob is severely damaged; when the bending angle of the corn cob is within the range of 150-155°, the corn cob is moderately damaged; when the bending angle of the corn cob is within the range of 155-170°, the corn cob is slightly damaged; when the bending angle of the corn cob is within the range of 170-180°, the corn cob is not damaged.

7. The evaluation method according to claim 5, wherein: The method for determining the damage level of the fall armyworm to corn yield is as follows: when the bending angle of the corn cob is less than 145°, the damage level of the fall armyworm to corn yield is level 9; when the bending angle of the corn cob is within the range of 145-150°, the damage level of the fall armyworm to corn yield is level 7; when the bending angle of the corn cob is within the range of 150-155°, the damage level of the fall armyworm to corn yield is level 5; when the bending angle of the corn cob is within the range of 155-170°, the damage level of the fall armyworm to corn yield is level 3; when the bending angle of the corn cob is within the range of 170-180°, the damage level of the fall armyworm to corn yield is level 1.

8. Use of the evaluation method according to any one of claims 3 to 7 in evaluating the resistance of transgenic insect-resistant corn.

9. The use according to claim 8, characterized in that The resistance evaluation includes resistance evaluation to Spodoptera frugiperda.

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