Exploring the use of microblog irradiation to kill underground pests such as tigers in greenhouses

　　Underground pests are omnivorous insects that live in the soil throughout their lives or at a certain stage in their lives and damage the roots, seeds, seedlings, or main stems near the soil surface. There are many types of underground pests. There are as many as 320 underground pests in our country. The most common underground pests are cutworms, mole crickets, golden needle insects, grubs, etc. Because underground pests last for a long time and live in the soil, they are a type of pest that is relatively difficult to control. Among them, cutworms belong to the Lepidoptera Noctuidae (Noctuidae), also known as root-cutting insects, night robbers, and commonly known as ground silkworms, which are polyphagous crop pests. When it occurs in large numbers, it will cause serious damage to crops, including Solanaceae, Cruciferae, Liliaceae, Cucurbitaceae, Gramineae, Rosaceae, Compositae, Leguminosae, etc., and these crops are widely planted in my country. . Especially in recent years, the harm of cutworms to agricultural production has been paid more and more attention.

　　In agricultural production, the current measures for the prevention and control of cutworms mainly include the following methods: First, manual and mechanical hunting. Clear the vegetable field and surrounding weeds in early spring, and at the same time shovel the soil layer of the ridge by about 3 cm, can effectively reduce the pupation amount and prevent the adult cutworms from laying eggs. In the early morning, lurking larvae were found around the injured seedlings, and they were caught every day for 10-15 days. Although this method had certain effects, the killing was incomplete, time-consuming and labor-intensive. The second is physical booby. Prepare sweet and sour liquid to trap and kill adult insects; use black light to trap and kill adult insects; before planting seedlings, select the weeds such as gray vegetables, squirrels, and bittersweed that cutworms like to piling to trap cutworm larvae, and then manually catch them. Although these methods are non-polluting, they kill insects slowly and are incomplete. The third is the bait trap method. Prepare poison bait and spread it between rows or between plants after sowing to trap and kill many underground pests such as cutworms and mole crickets. Although this method has a good hunting effect, the amount of poison in the bait is not easy to control, and the effect of small amount is not good. Large amount will cause residues, endanger crops, and pose safety risks to human and animal health. The fourth is the chemical control method. This method has good bactericidal effect and is easy to implement. This is currently the most commonly used method. However, when these highly toxic pesticides are applied, they will not only cause safety problems for users, but also cause pesticide residues and affect product quality. With the increase of larvae's resistance to pesticides, people use more and more pesticides, which will cause serious environmental pollution and seriously endanger human and animal health. Therefore, the country has issued many regulations restricting the use of chemical pesticides.

　　In view of the current problems of cutworms, there is an urgent need to find a method for killing cutworms that has good killing effect, is energy-saving, environmentally friendly and pollution-free, has low cost and is easy to operate. This research is to provide a method to kill cutworms by using the thermal and non-thermal effects of microwave technology. It uses purely physical methods to kill cutworms. The killing effect is good, and it is energy-saving and environmentally friendly, and has no impact on the environment, humans, and livestock. Pollution, low cost, and easy operation make the cutworm kill rate reach 100%.

　　1 Microwave working principle

　　The dielectric material is composed of polar molecules and non-polar molecules. Under the action of electromagnetic field, these polar molecules turn from the original random distribution state The orientations are arranged according to the polarity of the electric field, and under the action of the high magnetic field, these orientations are constantly changing according to the frequency of the alternating magnetic field. This process causes the movement and mutual friction of molecules, thereby generating heat [2-3]. At this time, the field energy of the alternating electric field is converted into heat energy in the medium, which causes the temperature of the medium to rise continuously. If the cutworm is irradiated with microwave energy, the microwave will cause the cutworm to produce a thermal effect, and the moisture in the soil will also generate a lot of heat due to mutual friction. The superposition of the two thermal energy makes the cutworm suffer a fatal blow. At the same time, under the action of microwave electromagnetic field, some molecules in the cutworm body will deform and vibrate, which will affect the cell membrane function, and even cause the cell membrane to rupture, lose its physiological function, and produce non-thermal effects to kill the cutworm.

　　2Advantages of microwave irradiation

　　One is to achieve the purpose of killing cutworms with “microwave energy”. The second is the killing method, which is an energy-saving, environmentally friendly and pollution-free method. It can replace chemical pesticides to kill cutworms, avoid the tedious application of pesticides, and ensure people's health. The third is that cutworms can be killed by only a few minutes of irradiation, which is highly efficient and fast. Fourth, the machine has low cost and is convenient for industrialization. Fifth, because the commonly used magnetron is used, the equipment is low in cost and easy to promote. Sixth, this method will not affect the plants while killing cutworms, has good economic and social benefits, and is worthy of wide application and promotion. Seventh, the control of most underground pests is basically similar to that of cutworms. As long as you master the growth characteristics and living habits of underground pests, you can use microwave irradiation to kill them.

　　3specific implementation process

　　When the aboveground part of the plant is found to be thin, poor growth, leaves withered and wilted with worm holes, or the seedlings are bitten off and wilted on the ground, it means that insect pests have occurred, and the existence of cutworms can be confirmed by using a microwave irradiation machine that kills cutworms. Kill. Choose to irradiate when the volumetric water content of the soil is 15% to 24%. As the moisture content increases, the irradiation time is extended accordingly. Choose the frequency of the microwave to be 2000～3000MHz, preferably 2450MHz. Choose the intensity of the microwave to be used as 1kW for 300～800cm2. In order to prevent microwave leakage and ensure personal safety, insert the microwave-irradiated metal cavity into the ground 1～3cm. The distance between man and machine is greater than 60cm. According to the biological characteristics of cutworms, the microwave irradiation area selected by the process is: the diseased part of the plant is the center, and the range is 5 to 15 cm. When microwave irradiation is completed, the soil temperature shall not be higher than 50℃. In order to increase the non-thermal effect of microwave killing cutworms and reduce the influence of thermal effect on plant growth, intermittent irradiation is used. The procedure is: turn on the microwave transmitter to irradiate for 60～80s, stop for 30～40s, repeat the irradiation 2 times, irradiate 60～80s each time; stop between 30～40s, Then use an infrared thermometer to detect the surface temperature of the irradiated tree trunk.

　　4killing effect

　　This research team conducted a test on tomato seedlings to kill cutworms in 3 vegetable greenhouse where tomatoes are grown. The tomato seedlings are about 70% of it was infested by cutworms, and a large number of worm holes appeared on the seedlings. The soil was opened for inspection. Cutworms dived 3～15cm underground. Using this method, the pest seedlings were placed in the microwave irradiation cavity of the microwave irradiation machine. Turn on the microwave transmitter 60s to stop, check that the cutworm is about 31% dead, then turn on the microwave transmitter 60s to stop, check that the cutworm is about 70% dead, turn on the microwave transmitter for the third time and irradiate 60s, check the cutworm The worms burst and all died. The infrared thermometer was used to detect the surface temperature of the trunk after being irradiated by the microwave as 48°C, and the irradiated plants were continuously observed for 5d, and the tomato seedlings grew normally. Repeat the above test method to check that the cutworm mortality rate is 100%, and it has no effect on plant growth.

　　The microwave transmitter, controller, power supply and unspecified technology used in the microwave irradiation machine in this study are all known technologies. In order to adapt to different plants, the irradiation machine described in this study is designed to have multiple sizes and can be changed.