A low temperature based method of solenopsis invicta killing

Abstract

The application discloses a low-temperature-based red imported fire ant killing method, which comprises the following steps: step S1: first-time nest filling: a 10-40 cm deep hole is dug in the center of an ant hill, and 1-2 L of liquid nitrogen is used to fill the nest; and step S2: second-time killing: after 3-6 days of the first-time nest filling, second-time killing is performed, wherein the second-time killing is physical killing, and specifically, 2-4 L of liquid nitrogen is used to fill the nest for the second time. The method is designed according to the migration rule of the red imported fire ant after the nest filling, has good killing effect, and can make the worker ant mortality reach 99.1%+ / -2.5% and the queen ant mortality (including breeding ants and larvae and pupae) reach 98.2%+ / -3.3%. The method is simple to operate, harmless to the environment and capable of playing a long-term effect.

Description

Technical Field

[0001] This invention relates to the field of pest control technology, specifically to a method for killing red imported fire ants based on low temperature. Background Technology

[0002] The statements in this section provide only background information relevant to the disclosure of this application and may not constitute prior art.

[0003] Red imported fire ants (Solenopsis invicta Buren), also known as imported fire ants or South American fire ants, are invasive ants originating from South America. They are social insects, typically living in colonies, and possess strong reproductive capabilities and environmental adaptability. Red imported fire ants are extremely aggressive and destructive, posing a significant threat to human health, infrastructure, agricultural production, and ecological balance due to their invasion and spread. Currently, the invasive species red imported fire ants is receiving widespread attention, and many experts are dedicated to researching methods for their control.

[0004] For example, there are biological control methods, chemical control methods, and physical control methods. Biological control mainly involves releasing the red imported fire ant's natural enemy, the "South American flea fly," to parasitize the red imported fire ants and control their population; however, this method can only attack the ants outside the nest and is difficult to reach the queen.

[0005] Physical control methods include burning, flooding, and nest destruction, which are less effective at killing ants. For example, Chinese patent CN100348099C discloses a method of burning red imported fire ants, using a liquefied petroleum gas torch to burn the ant colony in the nest, or electrically heating the soil near the nest. However, these methods are generally ineffective at killing the queen ant and thus fail to eliminate the red imported fire ants. Burning and flooding may even exacerbate the spread of the ants, further increasing the difficulty of control.

[0006] Chemical control is currently the main research method, using various contact pesticides or poisoned baits to kill red imported fire ants. However, it remains difficult to eradicate them completely. The main reasons are: First, red imported fire ant nests are deep, with the queen often located at the bottom. The typical depth of a red imported fire ant nest is 50-110 cm, with some reaching up to 2 meters. The queen is mainly distributed at the bottom, and some worker ants die before entering the nest, making it difficult to reach the bottom and effectively kill the queen. Second, the queen has unique feeding habits. The feeding order in a red imported fire ant colony is as follows: worker ants forage and then transfer nutrients to the larvae through intercourse; the larvae then regurgitate to provide the queen with the amino acids and soluble proteins needed for egg laying. If the food contains toxins that cause the death of worker ants or larvae, the queen may not feed, making it difficult to kill her with poison. Third, the number of queens in the nest is enormous, and their reproductive capacity is high. The red imported fire ants that have invaded my country are multi-queen ants, often containing a large number of queens in a single nest. The inventor's team has found as many as 253 queens in one nest. For a single nest, current control methods are insufficient to eliminate such a large number of queens. Red imported fire ant queens have an extremely high reproductive capacity; a single queen in a multi-queen nest can lay 300 eggs per day, and a single nest can produce an average of 4,000-6,000 winged reproductive ants per year. Even if most of the queens in a red imported fire ant nest are killed, the remaining few queens can quickly restore the population.

[0007] Liquid nitrogen is nitrogen gas that has been dissolved in water at extremely low temperatures. At normal atmospheric pressure, liquid nitrogen has a boiling point of -196.56°C. When liquid nitrogen is heated to its boiling point, it begins to evaporate, turning into nitrogen gas. The latent heat of vaporization of liquid nitrogen is approximately 100 joules per gram, or 100,000 joules per kilogram. The rapid evaporation of liquid nitrogen into nitrogen gas absorbs a large amount of heat, achieving a cooling effect. Furthermore, since nitrogen is a major component of the atmosphere, the evaporation of liquid nitrogen to form nitrogen gas does not cause environmental pollution.

[0008] Red imported fire ants can tolerate heat between 3.6℃ and 40.7℃; temperatures exceeding this range will kill them. While injecting large amounts of liquid nitrogen into the nest can rapidly lower its temperature, the nests are underground, typically 50-110cm deep, with some reaching 2m. The queen ant is primarily located at the bottom of the nest, and the depth and internal structure are not well understood. Therefore, when injecting liquid nitrogen, obstructions such as stones, bricks, and clods of earth often prevent the nitrogen from penetrating to a shallow depth. Furthermore, liquid nitrogen evaporates extremely quickly, rising upwards and making it difficult to achieve a low temperature at the bottom of the nest even with large injections. To overcome these technical challenges, the inventors of this invention conducted research based on the above technical background and ultimately developed this invention. Summary of the Invention

[0009] The purpose of this invention is to address the problems of current red imported fire ant control methods being difficult to eradicate and the poor effect of liquid nitrogen nest irrigation, by providing a low-temperature-based method for killing red imported fire ants. This method can scientifically and specifically kill the queen ant and eliminate red imported fire ants, while saving on extermination costs.

[0010] The technical solution of the present invention is as follows:

[0011] A method for killing red imported fire ants based on low temperature includes the following steps:

[0012] Step S1: First nest filling: Drill a hole 10-40cm deep in the center of the ant mound and fill the nest with 1-2L of liquid nitrogen;

[0013] Step S2: Second extermination: 3-6 days after the first nest-feeding, a second extermination will be carried out.

[0014] Preferably, in step S2, the second killing is a physical killing, specifically, 2-4L of liquid nitrogen is used for a second nest filling 3-6 days after the first nest filling.

[0015] Preferably, the second nest filling is done 4 days after the first nest filling.

[0016] Preferably, the hole dug in the center of the ant mound during the first nest filling is 30cm deep.

[0017] Preferably, 2L of liquid nitrogen is used to fill the nest for the first time.

[0018] Preferably, 2L of liquid nitrogen is used to fill the nest a second time.

[0019] Preferably, the second killing can also be achieved by spraying highly effective contact insecticides, and the amount of pesticide, spray range, and spray concentration can be routinely determined by those skilled in the art.

[0020] Compared with existing technologies, the advantages of this invention are:

[0021] 1. A method for killing red imported fire ants based on low temperature, supported by the migration pattern of red imported fire ants after being affected by nest flooding, discovered by the inventors, sets an appropriate time point to flood the red imported fire ant nest a second time, and then kills almost all of the red imported fire ant colony in two stages within the effective killing depth of liquid nitrogen. The worker ant mortality rate reaches 99.1% ± 2.5%, and the queen ant mortality rate (including reproductive ants and their larvae and pupae) reaches 98.2% ± 3.3%, which is suitable for eradicating red imported fire ants. The method is simple and efficient.

[0022] 2. A method for killing red imported fire ants based on low temperature. The method is green and has little impact on the environment. Compared with biological control and spraying pesticides, which have low returns and put new pressure on the environment, the method of injecting liquid nitrogen will not burden the environment and will not cause red imported fire ants to develop drug resistance. It belongs to the physical control method, which is more environmentally friendly and can play a long-term and sustainable role.

[0023] 3. A method for killing red imported fire ants based on low temperature. Based on the inventor's discovery and proper planning, only 4L of liquid nitrogen is needed to achieve high killing efficiency. Compared with liquid nitrogen drenching the nest once, only half the amount of liquid nitrogen is used to achieve twice the killing effect, which is twice as effective with half the effort and greatly saves the amount of liquid nitrogen used. While ensuring a high killing effect, it saves a lot of the cost of purchasing liquid nitrogen. Attached Figure Description

[0024] Figure 1 This is a graph showing temperature measurement data at different depths during a single nest filling process in Example 1;

[0025] Figure 2 The red imported fire ants that were removed after a single nest-filling process in Example 1;

[0026] Figure 3 This is a data graph showing the results of nest excavation after a single nest filling in Example 1. Detailed Implementation

[0027] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0028] Example 1: Study on the survival patterns of red imported fire ants when liquid nitrogen is poured into their nests

[0029] The inventors in this case discovered that, Figure 1 As shown, after injecting 8L of liquid nitrogen into a red imported fire ant nest at a depth of 30cm, the temperature at this depth dropped to -121℃. However, the temperature at a depth of 50cm remained around 7℃, failing to kill the queen ant in the lower layers. Therefore, injecting large amounts of liquid nitrogen into the nest may not be effective in killing the queen ant. Furthermore, liquid nitrogen is expensive, and injecting large amounts into a single nest is costly and not suitable for large-scale application.

[0030] Further research revealed:

[0031] When liquid nitrogen is poured into the nest, the extremely low temperature of the liquid nitrogen (-196.56℃) and the significant heat loss during evaporation cause a drastic drop in temperature in the area through which the liquid nitrogen flows and within a 10-20cm radius, resulting in the death of red imported fire ants in this area. After pouring 2L of liquid nitrogen into the nest, excavation revealed a worker ant mortality rate of 61.3±5.2% and a queen ant mortality rate of 25.2±6.7%.

[0032] Observations revealed that because many red imported fire ants survived in the nest, these surviving ants carried away the frozen-to-death ants, resulting in a large number of worker ant corpses, including some queen ants, appearing on the nest surface. The removed ant corpses... Figure 2 As shown.

[0033] Further excavation of the nests at different times after liquid nitrogen injection revealed, for example... Figure 3 As shown, in an untreated red imported fire ant nest, the queen ant is located at the bottom layer, specifically layers 9-11. Three days after liquid nitrogen treatment, when the nest was excavated, all the queen ants had moved to the middle layer, layers 4-5; no queen ants were found at the bottom. Six days after liquid nitrogen treatment, when the nest was excavated, all the queen ants had moved to the upper layer, layers 1-2. This indicates that after liquid nitrogen treatment, the ant colony perceives the nest as dangerous and migrates.

[0034] Example 2: Method for eliminating red imported fire ants - Two-time nest-drenching method with a small amount of liquid nitrogen

[0035] Experimental preparation:

[0036] Experimental tools: funnel for filling nests (mouth diameter 2.2cm, trumpet diameter 10.5cm, funnel tube length 30cm), shovel, Luoyang shovel, small soup spoon, tray, measuring tape, drilling machine, knife;

[0037] Selection of prevention and control areas:

[0038] Within Fucheng District of Mianyang City, designated areas with isolated outbreaks of red imported fire ants containing live nests are selected as control zones. A live nest is defined as one in which at least three red imported fire ants emerge and become active within 60 seconds of being disturbed. An isolated outbreak area is defined as one within a 500-meter radius of the affected area, free of red imported fire ants. The area of ​​an isolated outbreak area should be no less than 1 mu (approximately 0.16 acres) and no more than 5 mu (approximately 0.8 acres).

[0039] I. Experimental Procedure:

[0040] First nest filling: Use a Luoyang shovel to drill a hole about 30cm deep in the center of the ant mound, and put in a funnel (2.2cm in diameter, 10.5cm in diameter of the trumpet, and 30cm in length of the funnel tube). First, use a small amount of liquid nitrogen (2L) to fill the nest. After filling the nest, the red imported fire ant colony will move to the nest as a whole, and the queen will move from the bottom to the top of the nest.

[0041] Second flooding: Four days after the first flooding with liquid nitrogen, a small amount of liquid nitrogen (2L) is used again to flood the nest, which will kill the queen ant in the process of migration.

[0042] II. Data Recording:

[0043] The day after the second liquid nitrogen injection into the nest, using tools such as a drilling machine and shovels, the soil around the nest was dug up to expose the entire nest. Then, starting from the ant mound, the nest was layered in 10cm increments. Each layer of nest was placed in a corresponding tray, the soil clods in the nest were crushed, and a careful inspection was conducted to ensure all red imported fire ants were in the tray. The trays were then carefully inspected for queens, winged reproductive ants, reproductive ant larvae, and pupae in each layer. When queens, winged reproductive ants, reproductive ant larvae, or pupae were found, they were transferred to small boxes using a small spoon for preservation, and their numbers and survival status were recorded. To ensure no queens, winged reproductive ants, reproductive ant larvae, or pupae were missed, each layer of nest was inspected by two people, each person checking twice. After confirming that the nest layer is free of queen ants, winged reproductive ants, reproductive ant larvae, and pupae, mix the nest soil in the tray thoroughly. Take out approximately 80g of nest soil and count and record the number of live and dead eggs, worker ants, worker ant larvae, and pupae in the nest soil. Take three samples from each nest layer. Finally, weigh the total weight of the nest soil in that nest layer. Based on the average of the three samples, calculate the number of live and dead eggs, worker ants, worker ant larvae, and pupae contained in the nest soil of that nest layer.

[0044] III. Experimental Results

[0045] The results showed that after two applications of liquid nitrogen to the nest, the mortality rate of worker ants reached 99.1% ± 2.5%, and the mortality rate of queen ants (including reproductive ants, their larvae, and pupae) reached 98.2% ± 3.3%. The mortality rate was significantly higher than that after a single application of liquid nitrogen.

[0046] This method can quickly and efficiently kill all queen ants, and uses a small amount of liquid nitrogen. Using 4L of liquid nitrogen can achieve very high killing efficiency, is economical and environmentally friendly, and can achieve the purpose of killing red imported fire ants.

[0047] Example 3 - Red imported fire ant control effect - Two-time nest irrigation method with a small amount of liquid nitrogen

[0048] Data recording of prevention and control effectiveness:

[0049] Before planting the nests, a survey was conducted to determine the number of live ant nests per unit area. In areas where red imported fire ants were present independently, a comprehensive survey was performed to locate the nests, marking their locations with small red flags. The number of ant mounds and the spatial distribution of nests were recorded, and the number of live nests per unit area was calculated. A bait trapping method was then used to investigate the number of active worker ants per unit area. Based on the area and topography of the red imported fire ant outbreak zone, areas with ant activity were selected, and 10 monitoring bottles were placed 10 meters apart, each marked with a small red flag. After 30 minutes, the trapped ants were collected, identified, and counted. The average number of red imported fire ants attracted per bait bottle was calculated.

[0050] One month after the second liquid nitrogen treatment of the nests, a second survey was conducted using the same method to determine the extent of red imported fire ant infestation following the liquid nitrogen treatment. Based on the survey data before and after the liquid nitrogen treatment, the control effect in the affected area was calculated using the following formula.

[0051] Elimination rate of live ant nests per unit area: Elimination rate of live ant nests (%) = (1 - number of live ant nests per unit area after control / number of live ant nests per unit area before control) × 100

[0052] Red imported fire ant worker reduction rate per unit area: Worker reduction rate (%) = (1 - Number of red imported fire ant workers attracted after control / Number of red imported fire ant workers attracted before control) × 100

[0053] IV. Experimental Results

[0054]

[0055] In two isolated red imported fire ant infestation areas in Fucheng District, Mianyang City, we used a two-stage liquid nitrogen dredging method to control red imported fire ants. After one month, the reduction rates of live ant nests per unit area were 96.0% and 100%, respectively, and the reduction rates of worker ants per unit area were 96.8% and 100%, respectively. The two-stage liquid nitrogen dredging method can quickly and efficiently kill red imported fire ants while being environmentally friendly.

[0056] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A method for killing red imported fire ants based on low temperature, characterized in that, Includes the following steps: Step S1: First nest filling: Drill a 30 cm deep hole in the center of the ant mound and fill the nest with 1-2 L of liquid nitrogen; After filling the nest, the red imported fire ant colony will relocate as a whole, with the queen moving from the bottom to the top of the nest. Step S2: Second extermination: Four days after the first nest-feeding, a second extermination will be carried out; In step S2, the second killing is a physical killing, specifically using 2-4L of liquid nitrogen to perform a second nest flooding; killing the queen ant in the migration process; In step S1, liquid nitrogen is used to fill the nests using a nest-filling funnel with a length of 30cm. Data recording of prevention and control effectiveness: Before filling the nests, a field survey was conducted to investigate the number of live ant nests per unit area. In areas where red imported fire ants were found independently, a comprehensive field survey was conducted to locate the nests, and red flags were used to mark their locations. The number of red imported fire ant mounds and the spatial distribution of the nests were recorded, and the number of live ant nests per unit area was calculated. The number of active worker ants per unit area was investigated using a baiting method. Based on the area and topography of the areas where red imported fire ants were found independently, 10 monitoring bottles were placed in areas where red imported fire ants were active. The bottles were spaced 10 meters apart and marked with red flags. After 30 minutes, the attracted red imported fire ants were collected, identified, and counted. Calculate the average number of red imported fire ants attracted in a single monitoring bottle; One month after the second nest-drenching, a survey was conducted using the same method to determine the extent of red imported fire ant infestation after liquid nitrogen nest-drenching. Based on the survey data before and after liquid nitrogen nest-drenching, the control effect in independent red imported fire ant outbreak areas was calculated using the following formula: Reduction rate of live ant nests per unit area: Reduction rate of live ant nests (%) = (1 - number of live ant nests per unit area after control / number of live ant nests per unit area before control) × 100; Red imported fire ant worker reduction rate per unit area: Worker reduction rate (%) = (1 - number of red imported fire ant workers attracted after control / number of red imported fire ant workers attracted before control) × 100.

2. The method for killing red imported fire ants based on low temperature according to claim 1, characterized in that, The amount of liquid nitrogen used for the second filling of the nest was 2L.

3. The method for killing red imported fire ants based on low temperature according to claim 1, characterized in that, Step S1 is: fill the nest with 2L of liquid nitrogen.

4. The method for killing red imported fire ants based on low temperature according to claim 1, characterized in that, The funnel opening of the irrigation trough has a diameter of 2.2 cm, and the horn diameter has a diameter of 10.5 cm.

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