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Control technology of stored grain pests
The prevention and control work should face all possible pests and meet the requirements of safety, economy and effectiveness. The prevention and control of stored grain pests should follow the principle of "prevention first, comprehensive control", take "prevention" as the basic means of prevention and control, organically combine various prevention and control methods according to different situations, adjust measures to local conditions, foster strengths and avoid weaknesses, and carry out targeted comprehensive control to achieve the best control effect. The prevention and control of storage management is to artificially create ecological conditions that are conducive to grain storage and not conducive to pests, so as to control the occurrence and development of pests and achieve the purpose of safe grain storage. This control technology is simple and easy to operate, saving costs. The specific contents include: cleaning and sanitation, pest control of empty warehouse and empty equipment, isolation and protection, and improving warehouse conditions.

Cleaning is a basic and important prevention and control method. Cleaning and sanitation work can eliminate insect sources and food sources, especially in winter, because overwintering pests are the basic pests in the coming year, and eliminating them will lay a good foundation for the prevention and control work in the coming year. The cleaning and sanitation work should be "bright inside the warehouse, no three things outside the warehouse (no garbage, sewage and weeds)", so that pests can't get habitat. Because the pests are relatively small and hidden, it is inevitable that a small amount of pests will remain after cleaning up empty warehouses and equipment. These remaining pests have considerable hunger tolerance and can survive without moving or feeding. Therefore, it is very necessary to poison with pesticides once. The pesticides used for disinfection and disinfestation in empty warehouses are dichlorvos, trichlorfon and phoxim. Pests mainly come from mutual infection and circular transmission. Isolation protection refers to measures to prevent pests from spreading from infected stored grain and equipment to uninfected grain and protect pest-free grain. In this work, we should do a good job in "three isolation" (equipment warehouse is isolated from grain depot, processing plant is isolated from grain depot, dormitory, office and laboratory are isolated from grain depot) and "five separation" (variety separation, grade separation, dry-wet separation, new product separation and insect separation). Improving warehouse conditions is a necessary measure to prevent pests from entering the warehouse. The warehouse should be closed and equipped with insect-proof doors and windows. It is best to have a round corner for cleaning. The floor should be moisture-proof to prevent groundwater from rising. Farmers' simple warehouses can use dry sand as the bottom and bricks as the top. A grain processing factory that used to be an elevator can be transformed into a grain processing factory with an air duct, so that pests cannot survive in the inner wall of the air duct. In addition, we can also do a good job in pest detection and forecasting, find out the situation of pests in time, and provide direct basis for prevention and control. Inspection and prediction are important parts of warehouse management and prevention. Chemical control is a method to control stored grain pests directly or indirectly by using toxic chemicals. Chemical control has obvious effect on killing rampant pests, which is incomparable to other control technologies. It is an effective measure to prevent pests by using grain protectants and killing insects in empty warehouses before storage. Because the pesticides currently used have certain side effects on people and livestock, if pesticides are used for a long time to kill stored grain pests, pests will become resistant to some pesticides and fail. Therefore, we must fully understand the relationship between pesticides, pests and their environmental conditions, use drugs rationally, give full play to the control potential of pesticides, and minimize the harm of pesticides.

There are many kinds of pesticides. According to the dosage form used, it can be divided into solid, liquid and gas insecticides; According to the way it enters insects, it can be divided into stomach poison, contact poison and fumigant. According to its chemical composition and source, it can be divided into inorganic pesticides, organic pesticides and microbial pesticides. At present, the main pesticides used in grain storage are aluminum phosphide, zinc phosphide, chloropicrin, trichlorfon, dichlorvos, malathion, zinc thion, fenpropathrin and deltamethrin. Different pesticides have different physicochemical properties and different application methods. When using pesticides, we should pay attention to seize the opportunity, apply pesticides in time, and choose pesticides according to the types of harmful insects. If the resistance to chloropicrin is strong and the resistance to aluminum phosphide is weak, aluminum phosphide should be used to control pests mainly caused by sawflies. Another example is to control pests, mainly moths. Because moths are mostly active in the space and surface of grain, dichlorvos with weak penetration, high toxicity and low price can be used. On the basis of continuous practice, improve the use technology of pesticides. Such as "double low" technology, gap fumigation, airflow fumigation, circulation fumigation, decompression fumigation, mixed fumigation and so on. Insecticides are toxic to people and animals, so pay attention to safety when using them. Especially when using highly toxic chemicals such as aluminum phosphide and chloropicrin, we should strictly abide by the safety operation procedures. In order to reduce the harm of pesticides to people and livestock, we should choose pesticides with high efficiency, low toxicity, low residue, high purity and suitable residue period, and limit the types and conditions of chemicals used for grain storage. For example, flour cannot be fumigated with chloropicrin, and each batch of wheat can only be fumigated 1 time in 1 year. It is necessary to strictly implement the pesticide residue standards in food to prevent people and animals from eating poisoned food for a long time and causing chronic poisoning.

Residue standard of harmful substances

Project index (mg/kg)

Malathion shall not exceed 3

Phosphate (calculated as PH3) shall not exceed 0.05.

Cyanide (calculated by HCN) shall not exceed 5

Chloropicrin shall not exceed 2

Carbon disulfide shall not exceed 10. Strengthen plant quarantine, put an end to the introduction of foreign dangerous pests and prevent the spread of pests that have been quarantined in China.

2, clean and hygienic. From grain harvesting and drying to storage, storage, transportation, processing and sales, all relevant places, equipment, utensils and machinery and equipment should be clean and hygienic. After threshing, clean up the grain field and residue, and deal with insect grain and insect debris in time.

3. Low temperature measures. When the temperature is lower than 8℃, stored grain pests will enter a dormant state. When the temperature drops below 0℃ for a certain period of time, pests may die. The specific lethal low temperature and the required time vary with the species and state of pests. In cold winter, you can choose dry and cold weather, store the grain in time after thinning and freezing outdoors, or open the window for ventilation when the temperature outside the warehouse is lower than the warehouse temperature after late autumn and it is dry, so that the warehouse temperature and grain temperature can be reduced to below 10℃. But freezing is not suitable for grains and peanuts with high water content.

4. High temperature measures. The temperature above 35℃ is not suitable for the survival of pests and mites. When the temperature is as high as 48 ~ 52℃, pests will die quickly, and the quality of edible and feed grain will not be damaged. The specific methods are: sun exposure; In rainy season, a dryer is used to process a large amount of wet grain; Equipment and tools for high-temperature treatment of stored grain with steam; Soak the broad beans or peas infected with the bean weevil in boiling water for 25-28 seconds, then quickly soak them in cold water and spread them out to dry.

5, gland prevention and treatment. For pests that gather on the grain surface to lay eggs, cover the grain pile tightly before the adults emerge from the grain surface, so that the adults cannot go out and die.

6. Sealed storage and anoxic storage. The dried grain is sealed and stored, so that the respiration of the grain consumes oxygen and discharges carbon dioxide; Or the lack of oxygen in the warehouse caused by machinery and tools will lead to suffocation and death of pests. Vacuum nitrogen filling or carbon dioxide filling can also be used.

7, wind pest control. According to the different specific gravity of pests and impurities in cereals, pests and impurities are separated by wind.

8. Screening and pest control. According to the difference of particle size and insect body size, insect impurities are removed by screening.

9. Disinfection of bedding. The grain pile at the bottom of bedding can be treated with malathion and clay powder with high efficiency and low toxicity.

10, insect-proof line. Insect-proof lines for pesticides (such as malathion) should be set around when drying grain, driving insects by wind or screening. ?

1 1. Apply grain protectant. For the grain with safe moisture content, a proper amount of malathion can be used for mixing at the grain temperature below 30℃, and the validity period is one year, so the processed grain can be safely supplied. ?

12, fumigation. ?

13, biological control. Applying Bacillus thuringiensis to some moth larvae such as Indian moth and pink moth at the depth of 10 cm on the surface of grain can protect grain safely and effectively.