Application of rifampicin as synergist in preparation of aphid insecticide

Abstract

The application discloses application of rifampicin in preparation of a Myzus persicae insecticide.

Description

Technical Field

[0001] This invention belongs to the field of insecticide adjuvant technology, specifically relating to the application of rifampicin as a synergist in the preparation of a peach aphid insecticide. Background Technology

[0002] The peach aphid (Myzus persicae), belonging to the family Aphididae in the order Hemiptera, is one of the world's most important economic pests, causing significant damage to over 400 species of crops across more than 80 families and genera, such as cabbage, kale, tobacco, and peach trees. Currently, the control of peach aphids worldwide relies almost entirely on the use of chemically synthesized insecticides. This has led to varying degrees of resistance in peach aphids to more than 80 types of chemical pesticides, mainly including organophosphates (such as chlorpyrifos and phoxim), pyrethroids (such as cyhalothrin and deltamethrin), carbamates (such as carbofuran and imidacloprid), and neonicotinoids (such as imidacloprid and thiamethoxam). From 2017 to 2018, field resistance monitoring results of peach aphid populations in Guiyang City, Guizhou Province, showed that the resistance of peach aphids to imidacloprid, thiamethoxam, chlorpyrifos, thiamethoxam, and bromocyanamide increased significantly by 5.6-115.0 times. In 2018, the resistance level of peach aphid populations in Ningxiang, Hunan Province to acetamiprid and imidacloprid reached a moderate level, with resistance multiples of 25 times and 21 times, respectively. The resistance level of peach aphid populations in Shandong, Hubei, Beijing, and Liaoning Provinces to imidacloprid has reached 39-203 times.

[0003] Although the use of chemical pesticides causes many problems, they remain necessary in integrated pest management. In this context, in addition to developing novel insecticides, the effective reuse of traditional insecticides can be considered. Therefore, screening for synergists that can enhance insecticide toxicity and be used in conjunction with insecticides is a feasible approach, and the time and financial investment in developing synergists is relatively low. Synergists are considered a simple tool for overcoming metabolic resistance in insect resistance control, and they can also delay the development of resistance. These natural or synthetic substances can improve the lethality and effectiveness of certain existing insecticides, while they themselves are considered non-toxic or less toxic to the target pests. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide the application of rifampicin as a synergist in the preparation of peach aphid insecticide.

[0005] The present invention relates to the application of rifampicin as a pesticide synergist in the preparation of a peach aphid insecticide, wherein the insecticide contains 200 mg / L rifampicin.

[0006] Compared with existing technologies, this invention has significant beneficial effects. As can be seen from the above technical solutions, this invention uses rifampicin as a substance to enhance the toxicity of insecticides. When combined with imidacloprid, bromocyanamide, and thiamethoxam, the toxicity of these three insecticides against the third instar nymphs of the peach aphid is significantly enhanced compared to current treatments using only insecticides. The enhancement multiples are 2.72 times, 3.59 times, and 2.41 times, respectively. Furthermore, after rifampicin treatment, the weight, lifespan, and number of offspring of the peach aphid are significantly reduced to 2.00 times, 1.79 times, and 3.04 times, respectively; the development time from the second instar nymph to adult is significantly prolonged, reaching 1.33 times. This invention demonstrates the significant effectiveness of using rifampicin as a candidate synergist to overcome the metabolic resistance of aphids to insecticides. Detailed Implementation

[0007] Example 1:

[0008] 1. Rifampicin treatment for peach aphid nymphs

[0009] (1) Weigh 2 mg of 98% rifampicin and put it into a 10 mL quantitative bottle. Then add the pre-prepared artificial feed liquid for peach aphids to the 10 mL mark to fully dissolve the rifampicin. The final concentration of rifampicin is 200 mg / L.

[0010] (2) Using a pipette, 120 μl of artificial feed containing rifampicin was transferred between two stretched Parafilm membranes. The Parafilm membrane covered one side of the open end of a glass double-ended tube (7.5 cm long and 2.5 cm in diameter). Fifty healthy second-instar nymphs were then randomly selected and placed inside the Parafilm membrane. The other end of the double-ended tube was covered with nylon mesh. The control group, i.e., peach aphid nymphs, was fed the same artificial feed without any treatment. Each treatment was repeated in four replicates. Mortality rates were recorded at 48 and 96 hours.

[0011] Table 1. Mortality rate of peach aphids after treatment with 200 mg / L rifampin

[0012]

[0013] Note: The English letters are from an independent samples t-test. If the lowercase letters in the same column are different, it means that the difference is significant at the 0.05 level; otherwise, it is not significant. The same applies below.

[0014] As shown in Table 1, within 96 hours, there was no significant difference in mortality rate between the rifampicin-treated group and the control group. This indicates that feeding with 200 mg / L rifampicin does not directly cause significant mortality in peach aphids.

[0015] 2. Observe the fitness of peach aphid nymphs after treatment with rifampicin.

[0016] First, the control group and the peach aphid nymphs that survived 48 hours of rifampicin treatment were transferred to leaf discs with a diameter of 3.5 cm made of cabbage leaves. Then, the changes in the fitness of the peach aphids were observed from four aspects.

[0017] (1) Body weight: Twenty peach aphid nymphs were randomly selected from the control group and the rifampicin treatment group, placed on weighing paper, and then weighed using an electronic balance. Each treatment was repeated 5 times.

[0018] Table 2. Changes in body weight of peach aphids after treatment with 200 mg / L rifampin

[0019]

[0020] As shown in Table 2, compared with the control group, the body weight of the rifampicin treatment group decreased significantly by 2.0 times.

[0021] (2) Lifespan: Ten peach aphid nymphs from the control group and the rifampicin treatment group were randomly selected and placed on new leaf discs. The survival of the aphids was observed at a fixed time each day. Each treatment was replicated 10 times.

[0022] Table 3. Lifespan changes of peach aphids after treatment with 200 mg / L rifampin

[0023]

[0024] As shown in Table 3, compared with the control group, the lifespan of the rifampicin-treated group decreased significantly by 1.8 times.

[0025] (3) Number of offspring: Ten peach aphid nymphs from the control group and the rifampicin treatment group were randomly selected and placed on new leaf discs. The number of aphid offspring was observed and counted at a fixed time each day, and the newly produced nymphs were removed on the same day.

[0026] Table 4. Changes in the number of offspring produced by peach aphids after treatment with 200 mg / L rifampicin

[0027]

[0028] As shown in Table 4, compared with the control group, the number of offspring in the rifampicin treatment group decreased significantly to 3.0 times.

[0029] (4) Development time: Ten peach aphid nymphs from the control group and the rifampicin treatment group were randomly selected and placed on new leaf discs. The number of nymphs and the number of molts were investigated every 24 hours until adult aphids were reached, and the development time was recorded. Each treatment was replicated 10 times.

[0030] Table 5. Changes in the development time of peach aphids after treatment with 200 mg / L rifampicin

[0031]

[0032] As shown in Table 5, compared with the control group, the number of development days in the rifampicin treatment group was significantly prolonged by 1.3 times.

[0033] Example 2:

[0034] Toxicity determination of peach aphid nymphs

[0035] (1) The toxicity of insecticides to peach aphids was determined by leaf immersion method. First, imidacloprid, bromocyanamide and thiamethoxam were prepared into high-concentration stock solutions (1000 mg / L) with acetone and stored in a refrigerator at 4℃ for later use. Then, 0.1% Triton-100 emulsion was prepared with sterile water. The three stock solutions prepared in advance were diluted with the emulsion to 5-6 series concentrations (imidacloprid 2, 4, 8, 16, 32 mg / L; bromocyanamide 2, 4, 8, 16, 32 mg / L; thiamethoxam 16, 32, 64, 128, 256 mg / L). Clean cabbage leaves were prepared into leaf discs using a 3.5 cm diameter perforator. The leaf discs were then immersed in a series of pesticide solutions (from low to high concentration) for 30 seconds, removed, and allowed to air dry indoors. The dried leaf discs were then placed, back side up, in 3.5 cm diameter plastic petri dishes containing 1.2% agar. Leaf discs treated with the emulsion served as a control. Healthy, uniform third-instar nymphs were collected using a brush and transferred to the leaf discs. Each pesticide solution was repeated four times for each concentration, with 15 nymphs per replicate.

[0036] The petri dishes inoculated with aphids were placed in an incubator at 26±1℃, approximately 75%RH, and a 16 h: 8 h light-dark cycle. The experimental results were examined after 48 h. The mortality criterion was that the aphids could not coordinate their movements when lightly touched with a paintbrush. A mortality rate of less than 20% in the control group was considered a valid test.

[0037] (2) Fifteen second-instar nymphs of the peach aphid were fed with artificial feed containing 200 mg / L rifampicin. After 48 hours, the surviving aphids were transferred to leaf discs soaked in insecticide solution. The solution preparation and treatment were the same as in step (1) above. The concentrations of the three insecticides were: imidacloprid (1, 2, 4, 8, 16 mg / L), cyantraniliprole (0.5, 1, 2, 4, 8 mg / L), and thiamethoxam (5, 10, 20, 40, 80). The nymphs treated with insecticides alone served as a control. The aphid mortality rate was measured after 48 hours. Each treatment was performed in quadruplicate.

[0038] Table 6. Effects of combined treatments with rifampicin and insecticides on the toxicity of three insecticides.

[0039]

[0040] Note: LC 50The ratio is used to represent the relative toxicity index; the criterion for determining whether the toxicity difference between two is significant: if LC 50 If the 95% confidence limits of the ratios do not overlap, then the difference between the two is significant (*).

[0041] As shown in Table 6, compared with the use of insecticides alone, the toxicity of imidacloprid, bromocyanamide and thiamethoxam to peach aphids was significantly enhanced after rifampicin treatment, increasing by 2.72 times, 3.59 times and 2.41 times respectively.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments without departing from the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. The application of rifampicin as a pesticide synergist in the preparation of a peach aphid insecticide, wherein the pesticide is one of imidacloprid, bromocyanamide or thiamethoxam.

2. The application of rifampicin as a pesticide synergist as described in claim 1 in the preparation of a peach aphid insecticide, wherein the insecticide contains 200 mg / L rifampicin.

Images