Insecticide

Insecticides are a general term for a class of agents that can kill insects that harm crops, fruit trees, trees, vegetables, storage, and environmental sanitation, as well as parasites in livestock and poultry. Insecticides can be divided into two major categories: biological sources and chemical synthesis. The biological source insecticide comprises: 1 a preparation of an insecticidal active ingredient extracted from a higher plant, such as natural pyrethrin, rotenone, etc.; 2 an insecticide made by using a microorganism, mainly a fungus (such as Beauveria bassiana), Bacterial (dental bacillus) and viruses (such as Acariciid) three types; 3 insect physiologically active substances, such as pheromones. Chemical synthetic pesticides mainly include: inorganic insecticides (such as As2O3, sodium fluorosilicate Na2SiF6, etc.), organochlorine insecticides (such as chlordane, hexachlorocyclohexane, DDT, toxaphene, etc.), organic phosphorus Insecticides (such as dichlorvos, trichlorfon, dimethoate, malathion, chlorpyrifos, etc.), carbamate insecticides (such as carbaryl, acesulfame, etc.) and pyrethroid insecticides Agents (such as fenvalerate, cypermethrin, etc.). The main ways of insecticides to kill insects are: 1 The contact agent enters the body through the epidermis of the pest to cause the poisoning to die; 2 The stomach poison is directly absorbed by the gastrointestinal tract after being eaten by the pest, causing the poison to die; Some fumigated drugs are highly volatile, and their vapors enter the body through the respiratory tract of the pests, causing them to die. 4 The systemic drugs are first absorbed by the crops and transmitted to the whole plant. When the pests suck and eat the crops, they are poisoned and die. For example, pyrethroids have a strong contact effect, killing pine, carbaryl has contact and stomach toxicity, and dimethoate, 1059, etc., in addition to contact, the more prominent is the systemic action. The use of insecticides is a modern technology for controlling pests, which is convenient, fast, efficient and economical. In the past ten years, in addition to the use of high-efficiency, low-toxic, environmentally-contaminated varieties such as pyrethroid insecticides, new varieties such as microbial insecticides, insect growth regulators, and insect behavior control agents have also been developed. . Insecticides are biologically active against insects and are more or less toxic to humans, animals and other animals (see pesticide toxicity). This toxicity is classified into acute toxicity and chronic toxicity. Acute toxicity refers to the ingestion of a certain dose of insecticide by oral, dermal or respiratory inhalation, which can cause acute pathological toxicity in a short period of time. Oral toxicity, although the most important in acute toxicity, is often more important in the production of poisoning, skin contact or respiratory intake when applying insecticides. Chronic toxicity refers to the continuous consumption, exposure or inhalation of pesticides that are lower than the acute poisoning dose for a long period of time, causing toxicity of chronic pathological reactions. The most notable of the chronic toxicity is teratogenic, genetic mutations, and the risk of carcinogenesis. Some organochlorine pesticides accumulate in the human body, causing cumulative poisoning; some organophosphorus pesticides have delayed neurotoxicity, which are chronic toxicity. After the application of pesticides, most of them are degraded into non-toxic substances under the action of physical, chemical and biological factors, but trace pesticides remain in agricultural products and the environment for a certain period of time, including soil and water. Atmosphere and other animal and plant bodies. This residual pesticide may pose a potential hazard to humans, animals or other animals. Excessive residues of pesticides in agricultural and livestock products may also affect human health in the case of long-term consumption. With the advancement of science and technology, the understanding of the toxicity of pesticides has been deepened. In the past, some pesticides were considered to be “poorly toxic” from the perspective of acute toxicity. Later, it was found that the impurities, or their metabolites, which were difficult to avoid in the production of the original drug, were chronically toxic and were banned. Toxicity is a difficult point in the development of new insecticides. Chronic toxicity is a key issue in the continued use of existing pesticides.