Method for preventing and controlling phosphine-resistant pests

Abstract

The invention relates to the technical field of pest control, in particular to a control method for phosphine-resistant pests. The action mechanisms and advantages of the S-methoprene and the phosphine are jointly utilized, and the phosphine-resistant pests are effectively prevented and controlled through the synergistic effect. The invention finds that under the action of S-methoprene, the biological characteristics and physiology and biochemistry of insect population can be changed, and the insect population becomes more sensitive to phosphine, so that the invention provides a new strategy for the treatment of phosphine-resistant pests, thereby keeping the effective use of the phosphine fumigant, prolonging the service life of the existing medicament, and reducing the cost. The control method provided by the invention has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of pest control, and in particular to a method for controlling phosphine-resistant pests. Background Art

[0002] Food security has always been an important issue of concern to the world. The variety and quantity of agricultural products stored each year are huge, and the losses caused by pests are also astonishing. For grain alone, the annual loss caused by pests is about 10%, and the loss of grain storage in rural areas is even greater. There are more than 80 species of insects, more than 50 species of mites, more than 100 species of microorganisms, and rodents in the grain pile, which harm the stored grain and form multi-level consumers, which influence and promote each other. The excrement and metabolic moisture of insects and mites can change the carbon-nitrogen ratio and water content of grain, further promoting microbial infection. Grain weevils and red flour beetles excrete a large amount of feces in grain piles, promoting the reproduction of streptomyces and bacteria, and accelerating grain rot. When pests harm, they release carbon dioxide and heat, gradually forming hot spots in the grain pile, which affects the quality, nutritional value and germination ability of grain, and then leads to the deterioration of stored grain quality. In order to survive and continue their offspring, most storage pests have little choice of food and are generally omnivorous. Storage pests are highly resistant to adversity and have strong reproductive capacity. A surviving female flour beetle can lay more than 1,000 eggs in its lifetime and reproduce continuously within a year. When pests are seen in grain piles, the insect population density has reached 1,000-2,000 per ton. In order to grow into strong insects, the larvae will consume everything they can reach. Pests in stored items will be regarded as potential pollution indicators, which not only reduce the value of the stored items, but also increase the cost of prevention and control, and have a great impact on the environment and people's psychology. In order to prevent stored grains from being attacked by pests, we must take active measures to prevent and control them.

[0003] Phosphine (PH3) is the most commonly used fumigation technology for storage pests worldwide due to its wide insecticide spectrum, strong diffusion, low cost and no residue. However, long-term, single and irregular use has led to a high degree of resistance in pests. Important storage pests such as the Indian grain moth, the grain borer, the grain borer, the rice weevil, the red flour beetle, the rusty red flour beetle, the book louse and the insect-loving book louse have all developed significant resistance to phosphine. Among the 25 red flour beetle populations surveyed, almost half of the populations showed phosphine resistance. The resistance frequency of red flour beetles and grain borers is much higher than it was 20 years ago. Since the development of new insecticides takes a long time and is costly, how to control and delay the spread of phosphine resistance in order to continue to use it effectively has become a hot topic in pest control.

[0004] S-methoprene is an insect growth regulator (IGRs) that interferes with the normal growth and development of insects, causing them to molt continuously in the larval stage, thus forming multiple larvae or intermediates, inhibiting the development of larvae into adults. In addition, it can also affect insect embryonic development, adult fecundity and heat resistance, and has no harm to the environment and non-target organisms. However, S-methoprene does not have a direct lethal effect on insects.

[0005] At present, the common combination of pesticides is the mixing of pesticides of the same type, that is, protectants and protectants, fumigants and fumigants. For example, a cytochrome P450 inhibitor (PBO) is used in combination with S-methoprene to control resistant strains of rice borers and their offspring, and the combined control effect of methoprene and cypermethrin on rice weevils, rice borers, and red flour beetles on brown rice and corn. This combination is more reflected in the effect of new compounds that may be produced after the two pesticides are compounded, or the effect of only one of the pesticides, and the synergistic effect of the two is not obvious.

[0006] There are many factors that cause pests to develop phosphine resistance, including active rejection of phosphine and protective coma, penetration resistance, enhanced free radical scavenging ability, reduced sensitivity of phosphine targets, enhanced detoxification ability and adjustment of energy metabolism patterns. How to develop a method for the combined use of pesticides for the efficient control of phosphine-resistant pests has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0007] In order to solve the above technical problems, the present invention starts from another idea, gives full play to the different action mechanisms of two different types of agents, and provides a method for controlling phosphine-resistant pests by utilizing the synergistic effects of different types of agents. Based on this, the following technical solution is proposed.

[0008] Firstly, the present invention provides a method for controlling phosphine-resistant pests, comprising: using S-methoprene and phosphine in combination to treat the phosphine-resistant pests.

[0009] In some embodiments, the phosphine-resistant pests are first treated with S-methoprene and then fumigated with phosphine.

[0010] In some embodiments, in the S-methoprene treatment, 0.1-5 mg (eg, 0.1 mg, 0.5 mg, 1 mg, 5 mg, etc.) of S-methoprene is applied per kg of storage.

[0011] In some embodiments, in the phosphine fumigation, the concentration of phosphine is 3-300 μg / L (for example, 3 μg / L, 5 μg / L, 7 μg / L, 8 μg / L, 9 μg / L, 11 μg / L, 13 μg / L, 15 μg / L, 20 μg / L, 22 μg / L, 30 μg / L, 36 μg / L, 40 μg / L, 42 μg / L, 60 μg / L, 80 μg / L, 100 μg / L, 120 μg / L, 150 μg / L, 200 μg / L, 250 μg / L, 300 μg / L, etc.).

[0012] Preferably, the S-methoprene treatment time is more than 7 days.

[0013] Preferably, the phosphine fumigation time is more than 24 hours.

[0014] In some embodiments, the control method has a lethal effect on F0 adults.

[0015] In some embodiments, the control method has a larval lethal effect.

[0016] In some embodiments, the control methods have an egg-suppressing effect.

[0017] In some embodiments, the control method has a pupal-inhibiting effect.

[0018] In some embodiments, the control method has the effect of killing phosphine-resistant pest progeny.

[0019] In an environment of low concentration of S-methoprene (preferably the concentration of S-methoprene is 0.1~0.6 mg / kg stored product), resistant pest eggs can complete their life cycle and develop into F1 generation adults, and their sensitivity to phosphine is significantly improved, which is more obvious than the sensitivity of F0 generation adults to phosphine under the action of high concentration of S-methoprene.

[0020] In the specific implementation process, the phosphine-resistant pests include but are not limited to Tribolium castaneum and the like.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention utilizes the action mechanism and advantages of S-methoprene and phosphine together to effectively control phosphine-resistant pests through synergistic action. The present invention finds that under the action of S-methoprene, the biological characteristics and physiological and biochemical properties of insect populations change, and they become more sensitive to phosphine. Therefore, the present invention provides a new strategy for the control of phosphine-resistant pests, thereby maintaining the effective use of phosphine fumigants and extending the service life of existing agents. The control method of the present invention has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure shows the lethal effect of the combined use of S-methoprene and phosphine on the adults of Tribolium castaneum. 1 and 5 in the figure represent S-methoprene concentrations of 1 mg / kg and 5 mg / kg, respectively. CK is the anhydrous ethanol blank control, i.e., the single phosphine treatment group. CD, WH, and QH represent the three geographical populations of Chengdu, Wuhan, and Qihe, respectively.

[0023] Figure 2 The figure shows the lethal effect of the combined use of S-methoprene and phosphine on the larvae of Tribolium castaneum. 1 and 5 in the figure represent S-methoprene concentrations of 1 mg / kg and 5 mg / kg, respectively. CK is the anhydrous ethanol blank control, i.e., the single phosphine treatment group. CD, WH, and QH represent the three geographical populations of Chengdu, Wuhan, and Qihe, respectively.

[0024] Figure 3 The effect of the combined use of S-methoprene and phosphine on the hatching of Tribolium castaneum eggs. 1 and 5 in the figure represent S-methoprene concentrations of 1 mg / kg and 5 mg / kg, respectively. CK is the anhydrous ethanol blank control, that is, the single phosphine treatment group. CD, WH, and QH represent the three geographical populations of Chengdu, Wuhan, and Qihe, respectively.

[0025] Figure 4 The effect of the combined use of S-methoprene and phosphine on the F1 generation of adults of Tribolium castaneum. The 0.5 in the figure indicates that the concentration of S-methoprene is 0.5 mg / kg, CK is the absolute ethanol control (single phosphine treatment), and * and ** in the figure indicate that the difference between the same phosphine concentration and different methoprene concentrations is significant ( P <0.05) and the difference was extremely significant ( P <0.01). DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the following examples, the test insect Tribolium castaneum Tribolium castaneum The insects were collected from grain depots in Qihe, Shandong (QH), Chengdu, Sichuan (CD), and Wuhan, Hubei (WH), and cultured for several generations in the Storage Insects Research Laboratory of the National Grain and Material Reserves Administration Scientific Research Institute. They were artificially cultured at a temperature of 28±2℃ and a relative humidity of 70±5% without light, using wheat: oatmeal: whole wheat flour: yeast = 15:60:70:7 as feed.

[0028] The experimental reagents and instruments used in the following examples are as follows: 95.3% S-methoprene; anhydrous ethanol; a new formulation of phosphine (2% phosphine, 98% carbon dioxide); a phosphine gas detector (HL-210, range: 0-2000 ml / m 3 ); Phosphine gas alarm (HL-210, range: 0-200 ml / m 3 , the minimum indication is 0.1ml / m 3 ); Gas sampling bag; Gas conditioning box; Stereo microscope.

[0029] In the following examples, data processing was performed using Excel 2021 and IBM SPSS Statistics 25 for data processing and one-way ANOVA, and Duncan's new multiple range method in ANOVA was used for difference significance analysis. The mortality rate, corrected mortality rate, and hatching rate were calculated using the following formula: .

[0030] In the statistical graphs of the following examples, capital letters indicate that the difference between the same phosphine concentration and different methoprene concentrations is significant, and lowercase letters indicate that the difference between the same methoprene concentration and different phosphine concentrations is significant ( P <0.05).

[0031] Example 1 Determination of phosphine resistance level In this example, the phosphine resistance level was determined by referring to the method recommended by FAO "Recommended methods for the detection and measurement of resistance of agricultural pests to pesticides: Tentative method for adults of some major pest species of stored cereals with methylbromide and phosphine" (the phosphine concentration unit at the test temperature was converted from ppm to mg / L, and 1ppm was converted by the ideal state equation = 7.2×10 -4 mg / L): Adult insects were placed in a wide-mouth fumigation bottle of the same volume and the bottle mouth was sealed. After 4 hours of equilibrium, different concentrations of phosphine gas were injected. The mortality rate of each concentration ranged from 15% to 85%. After 20 hours of closed fumigation under normal breeding conditions, the gas was released in a fume hood for 0.5 hours. After the fumigation was completed, the number of dead test insects was counted, and the statistics were continued for 14 days. The selected test insects were all 14-day-old adults, each replicate contained 50 heads, and 3 replicates were set. The phosphine sensitivity baseline (LC50 =0.009 mg / L) to calculate the resistance ratio (RR). Resistance ratio = LC50 / 0.009 mg / L of Tribolium castaneum in different regions. The specific resistance ratios are shown in Table 1. Chengdu and Wuhan are sensitive strains, and Qihe is a medium-resistant strain.

[0032] Table 1 Phosphine resistance levels of Tribolium castaneum in different geographical populations

[0033] Example 2 Evaluation of the synergistic effect of S-methoprene and phosphine To ensure the consistency of the experimental samples, 500 adults that had emerged for 14 days were selected and placed in insect culture bottles. Whole wheat flour that had passed through an 80-mesh sieve was added. After being cultured in an incubator at a temperature of 28±2℃ and a relative humidity of 70±5% for 24 hours, the adults were sieved out of the bottles to obtain eggs of the same age. Some of them were used for egg evaluation experiments, and some were continued to be cultured until larvae and adults, thus obtaining 15-day larvae and 14-day adults for the experiment.

[0034] After diluting the S-methoprene original drug with anhydrous ethanol solution to three concentrations of 5 mg / L, 10 mg / L and 50 mg / L, mix the feed with the drug solution according to the set concentration to make 0.5 mg / kg, 1 mg / kg and 5 mg / kg (grain), and use the anhydrous ethanol solution as the blank control. After the anhydrous ethanol evaporates, take an appropriate amount of the prepared feed and put it in a clean insect bottle for testing and evaluation.

[0035] The fumigation experiment of phosphine was carried out in a gas-tight controlled atmosphere box. Different concentrations of phosphine gas were injected into the controlled atmosphere box using a micro-syringe, the gas in the box was sucked and mixed, and then the controlled atmosphere box was placed in an incubator for fumigation for 24 hours. Three groups of repetitions were set for each concentration, and a total of 6 concentration gradients were set, with no phosphine as a blank control. After the fumigation, the sealing film of the box was opened in the fume hood to diffuse the gas for 0.5 hours, and then a small amount of daily cultured feed was added to all the insect samples and moved into the incubator for culture. The death of the test insects was observed and recorded every day, and the statistics were continuously counted for 7 days and the corrected mortality rate was calculated.

[0036] 1. Effect of killing adults 800 adults from each of the three geographical populations that had emerged two weeks ago were placed in clean insect culture bottles and fed with artificial feed containing 1 mg / kg and 5 mg / kg of S-methoprene for 7 days, respectively. Then, a phosphine fumigation experiment was carried out. After 24 hours of closed fumigation, the gas was released for 0.5 hours. The survival number of adults was observed and recorded every day, and the statistics were kept for 7 consecutive days.

[0037] The results are as follows: The combined use of S-methoprene and phosphine has a mortality rate of 1. Figure 1As shown. For the populations in Chengdu, Sichuan (CD) and Wuhan, Hubei (WH), when the phosphine concentration was 9 μg / L, the mortality rate when phosphine was used alone was more than 50%; when the phosphine concentration was 15 μg / L, the mortality rates were 97.78% and 94.44%, respectively; and after combined use, when the phosphine concentration was 7 μg / L, the mortality rates of both increased significantly. Since the populations in Chengdu, Sichuan (CD) and Wuhan, Hubei (WH) are both phosphine-sensitive strains, as the phosphine concentration increased, the mortality rate of combined use was not significantly different from that of single use.

[0038] For the Shandong Qihe (QH) population, which has strong resistance to phosphine, when the concentration of phosphine was 120 μg / L, the mortality rate of phosphine alone was only 73.33%, and the mortality rate when 1 mg / kg methoprene was used in combination with phosphine increased to 83.33%, and the mortality rate when 5 mg / kg was used in combination was 85.56%, which was a significant difference. The mortality rate after using methoprene was higher than that of using phosphine alone, especially when combined with 5 mg / kg methoprene concentration. The difference was significant, except for the two doses of 20 and 80 at 1 mg / kg, the rest were also significantly different.

[0039] The above results show that for adults, especially resistant strains, the sensitivity to phosphine is significantly enhanced after short-term treatment with S-methoprene.

[0040] 2. Lethal larvae effect 800 15-day-old larvae from each of three geographical populations were fed with artificial feed containing 1 mg / kg and 5 mg / kg S-methoprene for 7 days respectively. Then, the fumigation experiment was carried out with the same phosphine concentration as that of the adults. After 24 hours of closed fumigation, the gas was diffused for 0.5 hours. The survival number of larvae was observed and recorded every day, and the statistics were kept for 7 consecutive days.

[0041] The results are as follows: The mortality rate of the combined use of S-methoprene and phosphine against the larvae of three geographical populations of Tribolium castaneum is as follows: Figure 2As shown in the figure, the mortality rate when the two were used in combination was significantly higher than that when phosphine was used alone. Similar to adults, since the population in Chengdu, Sichuan (CD) was more sensitive to phosphine, when the concentration of phosphine was 15 μg / L, the mortality rate when the combination was used was not significantly different from that when phosphine was used alone, and the mortality rate exceeded 95%. Unlike adults, methoprene was significantly more effective against larvae, and the vitality of larvae treated with methoprene was significantly reduced. Therefore, after phosphine fumigation, the mortality rate of larvae in the three geographical populations increased significantly, and was significantly higher than that when phosphine was used alone. For the population in Chengdu, Sichuan (CD) and the population in Wuhan, Hubei (WH), when the concentration of phosphine was 11 μg / L, the mortality rates of larvae combined with 5 mg / kg methoprene were 92.22% and 86.67%, respectively, and when the concentration of phosphine was 1 mg / kg, they were 85.56% and 75.56%, respectively, which were significantly different from the use of phosphine alone. For the Shandong Qihe (QH) population with a moderate level of resistance to phosphine, the corrected mortality of larvae after synergistic treatment with 120 μg / L phosphine and 5 mg / kg methoprene was 93.33%, and that of 1 mg / kg was 90.00%, while that of phosphine alone was only 73.33%, with significant differences.

[0042] The above results show that for larvae, the sensitivity to phosphine is significantly increased after treatment with S-methoprene, and the performance is more obvious than that of adults.

[0043] 3. Inhibit egg hatching effect 500 adults of 2-week-old eclosion from 3 geographic populations were placed in clean insect bottles. They were fed with artificial diets containing 1mg / kg and 5mg / kg S-methoprene for 7 days, and then the adults were taken out and placed in blank bottles. Blank whole wheat flour with a 80-mesh sieve was added. After culturing in an incubator at a temperature of 28±2℃ and a relative humidity of 70±5% for 24 hours, the adults were removed from the bottles to obtain eggs of the same age. This batch of eggs was defined as eggs produced by adults treated with S-methoprene. The eggs are the most tolerant insect stage, so the experiment increased the concentration of phosphine. The hatching of the eggs was observed and recorded every day, and the egg hatching rate was calculated for 7 consecutive days.

[0044] The results are as follows: The combined use of S-methoprene and phosphine had an effect on the hatching rate of eggs of Tribolium castaneum in three geographical populations. Figure 3 As shown in the figure, there was no significant difference between the egg hatching rate under the combined effect and that under phosphine alone. In addition, with the increase of phosphine concentration, the egg hatching rate generally showed a downward trend. For the more sensitive populations in Chengdu, Sichuan (CD) and Wuhan, Hubei (WH), when the phosphine concentration was 42 μg / L, the egg hatching rate was less than 50%; while for the population in Qihe, Shandong (QH), when the phosphine concentration was 120 μg / L, the hatching rate was still higher than 50%.

[0045] 4. Effect of killing F1 generation adults In the preliminary experiment, no F1 generation adults were produced in the non-adult stage of Tribolium castaneum treated with S-methoprene at a concentration of 1 mg / kg or above, while F1 generation adults could be obtained at a concentration of 0.5 mg / kg. Therefore, 1,200 eggs of the same age from three geographical populations were taken, half of which were cultured in feed containing 0.5 mg / kg S-methoprene, and the other half were cultured in normal feed until the adults two weeks after eclosion were subjected to phosphine fumigation experiments, and the survival number of adults was observed and recorded every day for 7 consecutive days.

[0046] The results are as follows: The combined use of S-methoprene and phosphine has a mortality rate of F1 adults of three geographical populations of Tribolium castaneum. Figure 4 As shown. With the increase of phosphine concentration, the mortality rate of F1 generation adults gradually increased, but the mortality rate of adults developed from eggs treated with 0.5 mg / kg methoprene was significantly higher than that of the control group. For the Chengdu (CD) population in Sichuan, only when the phosphine concentration was 7 μg / L, there was no significant difference between the F1 generation adults treated with methoprene and the control group; for the Wuhan (WH) population in Hubei, there was no significant difference between the treatment group and the control group only when the phosphine concentration was 3 μg / L and 7 μg / L, and there were significant differences at other concentrations, and even extremely significant differences at 11 μg / L and 13 μg / L. For the Qihe (QH) population in Shandong, there was a significant difference in the mortality rate between the F1 generation adults developed from eggs treated with methoprene and the control group, and the difference was extremely significant when the phosphine concentration was 40 μg / L, 100 μg / L, and 120 μg / L. When the phosphine concentration was 120 μg / L, the mortality rate of F1 generation adults not treated with methoprene was 75.55%, while the mortality rate of F1 generation adults developed from eggs at a concentration of 0.5 mg / kg was as high as 96.64%.

[0047] The above experimental results show that the combined use of low-dose S-methoprene and phosphine has different control effects on different stages of red flour beetles in a short period of time. Among them, the combined use of the two has the most significant control effect on the larvae of three geographical populations of red flour beetles, and is significantly higher than the effect of phosphine alone; when methoprene and phosphine are used together, 1 mg / kg of methoprene has a significant synergistic effect; the combined use of S-methoprene and phosphine has a less significant control effect on the adults and eggs of red flour beetles than on the larvae, but the combined use of the two is of great significance for controlling phosphine-resistant pests; in the low concentration environment of 0.5 mg / kg S-methoprene, the eggs can complete the life cycle and develop into adults, and the sensitivity of this offspring pest to phosphine is significantly increased. The synergistic insecticidal effect of S-methoprene and phosphine is more effective than the single use of phosphine.

[0048] In summary, the present invention studies the synergistic effect of S-methoprene and phosphine in preventing and controlling red flour beetles. The test results show that the sensitivity of red flour beetle adults and larvae to phosphine increases after a short-term life in feed treated with 1 mg / kg or 5 mg / kg of S-methoprene. The red flour beetle test insects that can complete the life cycle at a low concentration of 0.5 mg / kg produce progeny pests that become sensitive to phosphine, especially the resistance strains and larval insect stages are extremely significant, indicating that S-methoprene and phosphine have a significant synergistic effect when used in combination.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling phosphine-resistant pests, characterized in that: include: Use S-methoprene in combination with phosphine to treat phosphine-resistant pests.

2. The method according to claim 1, characterized in that First, use S-methoprene to treat phosphine-resistant pests, and then use phosphine to fumigate the phosphine-resistant pests.

3. The method according to claim 2, characterized in that In the S-methoprene treatment, 0.1 to 5 mg of S-methoprene is applied per kg of stored material; and / or the S-methoprene treatment lasts for more than 7 days.

4. The method according to claim 2, characterized in that: In the phosphine fumigation, the concentration of phosphine is 3-300 μg / L; and / or the time of the phosphine fumigation is more than 24 hours.

5. The method according to any one of claims 1 to 4, characterized in that The control method has the effect of killing F0 adults.

6. The method according to any one of claims 1 to 4, characterized in that The control method has a lethal effect on the larvae.

7. The method according to any one of claims 1 to 4, characterized in that The control method has an egg-suppressing effect.

8. The method according to any one of claims 1 to 4, characterized in that The control method has the effect of inhibiting pupae.

9. The method according to any one of claims 1 to 4, characterized in that The control method has the effect of killing the progeny of phosphine-resistant pests.

10. The method according to claim 1, characterized in that Phosphine fumigation is then performed after S-methoprene is used to treat phosphine-resistant pests to produce biological characteristics and physiological and biochemical changes.

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