A method for evaluating corn earworm damage to corn ears

Abstract

The application discloses a kind of evaluation Spodoptera frugiperda to corn ear damage method, belong to harmful insect ecological control technical field.The application first proposes a kind of new method by measuring corn ear bending angle to judge the damage degree of Spodoptera frugiperda to corn ear, specifically: corn milk ripening period, select the corn damaged by Spodoptera frugiperda, and measure corn ear bending angle, according to corn ear bending angle, the damaged condition of corn yield is evaluated.The application can not only efficiently, quickly and objectively judge the damage degree of corn ear, but also solve the problems of high difficulty in area measurement and large error caused by irregular damaged parts of corn ear in the existing evaluation method, provide a scientific basis for transgenic corn insect resistance evaluation, and have important significance for improving Spodoptera frugiperda control technology system.

Description

Technical Field

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

[0002] Corn, as an important food crop, serves as a link between crop cultivation and animal husbandry. During its growth, corn is susceptible to damage from pests, leading to reduced yields. Among these, the fall armyworm, native to tropical and subtropical regions of the Americas, is one of the most serious pests affecting corn growth. The fall armyworm is an omnivorous pest that feeds on the tender leaves, silks, and kernels of corn. During the seedling and ear stages, it congregates on the leaves and ears to feed, directly causing yield losses. Furthermore, its granular excrement mixed with the corn kernels exacerbates plant diseases, resulting in a significant reduction in corn quality.

[0003] Currently, genetically modified insect-resistant maize is the most effective method for controlling fall armyworm, not only reducing pesticide use but also minimizing labor costs, making it the best long-term control strategy. Before approval for planting, genetically modified insect-resistant maize requires a comprehensive environmental safety assessment, mainly including resistance evaluation (herbicide tolerance and insect resistance), survival competitiveness, exogenous gene drift, and biodiversity impact. However, the published environmental safety assessment standards for genetically modified insect-resistant maize only cover insect resistance evaluation for Asian corn borer, cotton bollworm, and armyworm, while a comprehensive insect resistance assessment for fall armyworm has not yet been established.

[0004] Since a resistance assessment system for the fall armyworm has not yet been established, current methods typically rely on those used for other lepidopteran pests such as the corn borer, primarily assessing the extent of damage to corn leaves. However, this approach is insufficient to accurately reflect the actual impact of the fall armyworm on corn ears. Furthermore, because the fall armyworm mainly damages corn ears, and the affected areas are irregular, measuring the affected area is difficult and prone to error, making it challenging to accurately assess the actual economic yield of corn. Therefore, establishing a scientific and systematic fall armyworm resistance assessment system is an urgent problem to be solved. This will not only help to objectively and efficiently evaluate the actual effects of transgenic insect-resistant corn but also provide important data for the subsequent research and development and promotion of new varieties. Summary of the Invention

[0005] The purpose of this invention is to provide a method for evaluating the damage caused by fall armyworm to maize ears, thereby addressing the problems existing in the prior art. This invention proposes for the first time a novel method for quickly, easily, and intuitively determining the degree of damage caused by fall armyworm to maize ears by measuring the bending angle of the maize ear. This method not only efficiently and quickly provides an objective assessment of the damage to the maize ear, but also solves the problems of high difficulty in area measurement and large errors caused by the irregularity of the damaged parts of the maize ear in existing evaluation methods. This provides a scientific basis for evaluating the insect resistance of transgenic maize and is of great significance for improving the fall armyworm control technology system.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides the application of the corn ear bending angle in the evaluation of the impact of fall armyworm damage on corn yield.

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

[0009] With the insect-infested side of the corn ear as the front, measure the angle formed by the insect damage on the cross-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 ear on one side, and extend the other side outward along the damaged outline of the cross-section as a straight line. The angle formed by the vertex and the two straight lines is recorded as the corn ear bending angle.

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

[0011] During the milk stage of corn, select corn plants damaged by fall armyworm, measure the bending angle of the corn ears, and assess the yield loss based on the bending angle of the corn ears.

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

[0013] With the insect-infested side of the corn ear as the front, measure the angle formed by the insect damage on the cross-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 ear on one side, and extend the other side outward along the damaged outline of the cross-section as a straight line. The angle formed by the vertex and the two straight lines is recorded as the corn ear bending angle.

[0014] Optionally, the assessment of maize yield damage may include an assessment of the extent of damage to maize ears and an assessment of the degree of damage to maize yield caused by the fall armyworm.

[0015] Optionally, when the bending angle of the corn ear is less than 145°, the corn ear is severely damaged; when the bending angle of the corn ear is in the range of 145° to 150°, the corn ear is heavily damaged; when the bending angle of the corn ear is in the range of 150° to 155°, the corn ear is moderately damaged; when the bending angle of the corn ear is in the range of 155° to 170°, the corn ear is slightly damaged; and when the bending angle of the corn ear is in the range of 170° to 180°, the corn ear is undamaged.

[0016] Optionally, the method for determining the level of damage is as follows: When the bending angle of the corn ear is less than 145°, the level of damage to corn yield by the fall armyworm is level 9; when the bending angle of the corn ear is between 145° and 150°, the level of damage is level 7; when the bending angle is between 150° and 155°, the level of damage is level 5; when the bending angle is between 155° and 170°, the level of damage is level 3; and when the bending angle is between 170° and 180°, the level of damage is level 1.

[0017] The present invention also provides the application of the evaluation method described herein in the evaluation of resistance to transgenic insect-resistant maize.

[0018] Optionally, the resistance assessment includes a resistance assessment against the fall armyworm.

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

[0020] This invention presents a novel, simple, and intuitive method for quickly assessing the extent of fall armyworm damage to corn ears by measuring the bending angle of the corn ear. Through artificial inoculation experiments, this invention demonstrates that the smaller the bending angle of the corn ear, the greater the damage. Compared to existing technologies, this invention not only efficiently and quickly assesses the degree of damage to corn ears objectively, but also solves the problems of high difficulty in area measurement and large errors caused by the irregularity of the damaged parts of the corn ear in existing evaluation methods.

[0021] The evaluation method provided by this invention can efficiently and simply assess the impact of fall armyworm on maize economic yield, provide a scientific basis for the evaluation of insect-resistant transgenic maize, and is of great significance for improving the fall armyworm control technology system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 Schematic diagram for measuring the bending angle of corn ears;

[0024] Figure 2 1-3 represent variety 1; 4-6 represent variety 2; 1, 2, 4, and 5 represent ears of fruit damaged by fall armyworm; 3 and 6 represent normal ears of fruit; the scale bar in the figure is 10cm. Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of 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 terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

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

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

[0031] The corn varieties are: variety 1 is Xianda 913, and variety 2 is Guidan 162. Both corn varieties were purchased from Guangzhou Seed Business Department in 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. After sowing, the corn was managed in a conventional manner. During the silking stage of the corn, the corn was inoculated with insects, with 40 plants of each corn variety inoculated.

[0035] 2. Artificial insect inoculation

[0036] When the filaments have grown 2-3 cm, use a paintbrush to transfer the larvae of the fall armyworm onto the filaments, transferring 30 larvae to each plant.

[0037] 3. Survey Records

[0038] 50-60 days after inoculation, when the corn ears enter the milk 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 the fall armyworm. With the borer side as the front, measure the angle formed by the borer damage on a cross-section perpendicular to the front. The measurement is taken with the deepest point of the borer as the apex. Draw one side parallel to the edge of the lower half of the ear, and the other side extending outwards along the damaged outline of the cross-section. Record the angle between this apex and the two lines as the bending angle of the corn ear. Figure 1 As shown.

[0040] 4. Data Statistical Processing

[0041] The measurement data of the bending angle of corn ears were statistically analyzed, and the damage rate of corn ears was calculated. The calculation method is as follows:

[0042] Corn ear damage rate = Number of damaged corn ears / Total number of corn ears × 100%.

[0043] Table 1 shows the statistical results of corn ear bending angle and corn ear damage rate. Phenotypic diagrams of some damaged ears are shown below. Figure 2 As shown.

[0044] Table 1. Bend angle of corn ears and damage rate of corn ears

[0045]

[0046]

[0047] As shown in Table 1, the overall data indicates that the damage rate of corn ears increases with decreasing bending angle; that is, the smaller the measured bending angle, the greater the degree of damage. When the bending angle is less than 145°, the corn ear is severely damaged; when the bending angle is between 145° and 150°, the corn ear is heavily damaged; when the bending angle is between 150° and 155°, the corn ear is moderately damaged; when the bending angle is between 155° and 170°, the corn ear is slightly damaged; and when the bending angle is between 170° and 180°, the corn ear is essentially undamaged.

[0048] Based on the above data and results, the damage level of corn yield was classified according to the bending angle caused by the fall armyworm to corn ears, as shown in Table 2.

[0049] Table 2. Grading Standards for the Degree of Damage to Maize by Fall Armyworm

[0050]

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

Claims

1. A method for evaluating the impact of fall armyworm damage on maize yield, characterized in that, Includes the following steps: During the milk stage of corn, select corn plants damaged by fall armyworm, measure the bending angle of the corn ears, and assess the yield loss based on the bending angle of the corn ears. The method for measuring the bending angle of corn ears is as follows: With the insect-infested side of the corn ear as the front, measure the angle formed by the damage caused by the insect infestation on the cross 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 ear on one side, and extend a straight line 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. The assessment of maize yield damage includes an assessment of the extent of damage to maize ears and an assessment of the level of damage to maize yield caused by the fall armyworm. When the bending angle of the corn ear is less than 145°, the corn ear is severely damaged; when the bending angle is between 145° and 150°, the corn ear is heavily damaged; when the bending angle is between 150° and 155°, the corn ear is moderately damaged; when the bending angle is between 155° and 170°, the corn ear is slightly damaged; and when the bending angle is between 170° and 180°, the corn ear is undamaged. The method for determining the damage level of fall armyworm to corn yield is as follows: when the bending angle of the corn ear is less than 145°, the damage level of fall armyworm to corn yield is level 9; when the bending angle of the corn ear is in the range of 145-150°, the damage level of fall armyworm to corn yield is level 7; when the bending angle of the corn ear is in the range of 150-155°, the damage level of fall armyworm to corn yield is level 5; when the bending angle of the corn ear is in the range of 155-170°, the damage level of fall armyworm to corn yield is level 3; and when the bending angle of the corn ear is in the range of 170-180°, the damage level of fall armyworm to corn yield is level 1.

2. The application of the evaluation method described in claim 1 in the evaluation of resistance to transgenic insect-resistant maize.

3. The application according to claim 2, characterized in that, The resistance assessment includes an assessment of resistance to the fall armyworm.

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