What are chemical pesticides? What are its basic categories?
With the continuous development of agricultural modernization, pesticides have played an irreplaceable role in ensuring crop yields, improving agricultural ecological structure, and achieving pest and disease control. Among them, chemical pesticides are still the "main force" of the global agricultural pest and disease control system. Although it also faces controversy in terms of environment and safety, scientific and reasonable understanding and use of chemical pesticides is a key link in achieving sustainable agriculture.
This article will systematically explain the full picture of chemical pesticides from the aspects of definition, mechanism of action, basic classification, common types, and application examples to help readers establish a comprehensive understanding.
1. What are chemical pesticides?
1. Definition
Chemical pesticides refer to agents that use artificially synthesized chemicals to control or kill pests such as diseases, insects, weeds, and rats in agricultural production.
They can act on the physiological system of pests through contact, stomach poisoning, fumigation, systemic conduction, etc., destroying their life activities and ultimately achieving the purpose of prevention and control.
2. Differences from biological pesticides
Project Chemical pesticides Biological pesticides
Source Artificial synthetic compounds Natural microorganisms, animal and plant extracts, etc.
Fast onset of effect Relatively slow
The duration of effect is generally longer and most are shorter
Environmental impacts may accumulate or remain Relatively environmentally friendly
Lower cost Higher
Although biological pesticides have developed rapidly in recent years, chemical pesticides still play a leading role in large-scale and rapid control of pests and diseases.
2. Main features of chemical pesticides
High efficiency: a small amount can achieve the ideal prevention and control effect;
Quick effect: can quickly act on pests, pathogens or weeds;
Broad spectrum: a pesticide may be effective for multiple objects;
Mature synthesis process: controllable production, suitable for large-scale industrial use;
Strong economic efficiency: has a high cost-effectiveness in agricultural prevention and control in developing countries.
However, it also has problems such as environmental pollution, pesticide damage, increased resistance and food safety that may be caused by improper use, so scientific use is crucial.
3. Basic classification methods of chemical pesticides
There are many ways to classify chemical pesticides, the most common ones include:
1. Classification by target (functional classification)
This is the most common and practical classification method. According to the objects of control, they can be divided into:
Category Common varieties of control objects
Insecticides Various agricultural pests Organophosphorus, pyrethroids, carbamates, etc.
Fungicides Pathogenic fungi Carbendazim, fenpropimorph, fluphenazine, etc.
Herbicides Weeds Glyphosate, paraquat, atrazine, ethochlor, etc.
Acaricides (Ac aricides) mites and acarid pests, hexythiazolin, avermectins (although they are biological sources, they are often included in this category)
Rodenticides: farmland mice and other rodents, bromadiolone, sodium dimethoate, etc.
Plant growth regulators (PGRs) control plant growth or ripening gibberellins, chlormequat, ethephon, etc.
Nematicides: soil nematodes, avermectins, sulfoxaflor
2. Classification by chemical structure (chemical structure/ingredients)
Classification by chemical structure or functional group, such as:
Pesticides are classified by structure:
Organophosphorus: dichlorvos, malathion (acts on Nervous system)
Pyrethroids: chlorfluanidine, permethrin (highly effective and low toxicity, widely used)
Carbamates: carbofuran, carbaryl (more toxic to warm-blooded animals)
Neonicotinoids (new): imidacloprid, acetamiprid (strong systemic effect)
Benzoylureas: inhibit insect chitin synthesis, such as hexaflumuron
Organochlorines (restricted use): DDT, hexachloride, etc.
Fungicides are classified by structure:
Benzimidazoles: carbendazim, thiophanate-methyl
Triazoles: fenpropimorph, tebuconazole (inhibit sterol synthesis)
Dithiocarbamates: mancozeb, mancozeb
Amides: oxadiazine, fluazinam
Herbicides are classified by mechanism of action:
Photosynthesis inhibitors: atrazine, atrazine
Hormone herbicides: 2,4-D, MCPA (simulated plant hormones)
EPSP inhibitors: glyphosate (blocks aromatic amino acid synthesis)
Glutathione synthetase inhibitors: acetochlor, etc.
3. Classification by mode of action (contact/systemic)
Contact pesticides: only act on the contact site, such as paraquat;
Stomach toxic pesticides: poisoning after insects ingest, such as dichlorvos;
Systemic pesticides: can be absorbed and transmitted by plants, such as imidacloprid;
Fumigation pesticides: kill insects in the form of gas, such as methyl bromide (has been restricted).
4. Examples of common chemical pesticides and their mechanisms of action
1. Glyphosate
Category: Herbicide;
Structural type: Aminophosphoric acid;
Mechanism of action: Inhibits EPSP synthase in plants, prevents the synthesis of aromatic amino acids, and ultimately leads to plant death;
Advantages: Effective against most weeds, low cost;
Problems: The promotion of glyphosate-resistant transgenic crops has caused controversy.
2. Imidacloprid
Category: Insecticide;
Structural type: Neonicotinoids;
Mechanism of action: Acts on the nicotinic acetylcholine receptors in the central nervous system of insects, causing paralysis and death;
Advantages: Low toxicity, high efficiency, and long-lasting effect;
Problems: Related to bee poisoning incidents, and has been banned in some countries.
3. Tebuconazole
Category: Fungicide;
Structural type: Triazole;
Mechanism of action: Inhibits sterol biosynthesis in pathogenic bacteria and prevents cell membrane formation;
Application: Widely used in wheat and fruit trees to prevent powdery mildew, rust, leaf spot, etc.
V. Risks and Challenges in the Use of Chemical Pesticides
Although chemical pesticides have brought great benefits to agricultural development, abuse or poor management have also brought many problems:
Environmental pollution: pesticide residues enter water bodies and soil, destroying the ecology;
Food safety: excessive residues affect consumer health;
Resistance issues: pests develop resistance after long-term exposure, resulting in reduced control effectiveness;
Non-target biological damage: such as toxicity to bees, birds, and aquatic organisms;
Human health risks: especially improper operation of highly toxic pesticides causing poisoning incidents.
Therefore, promoting scientific drug selection, precise application, green substitution, and regulatory supervision are the core directions for the future.
VI. Future development trends of chemical pesticides
Develop towards high efficiency, low toxicity, and low residue;
Integrate with biological pesticides, agricultural machinery, and digital agriculture;
Combining precision agriculture with variable application to improve application efficiency;
Develop pesticides with new mechanisms of action to deal with resistance issues;
New formulations such as nanopesticides and controlled release technology have become key breakthrough directions.
VII. Conclusion
Chemical pesticides are one of the cornerstones of the modern agricultural prevention and control system. Against the backdrop of a growing global population, limited arable land resources, and frequent extreme climates, the rational application of efficient and safe chemical pesticides is of great significance for ensuring food security and improving agricultural sustainability.
However, chemical pesticides are by no means a "master key". Only by incorporating them into a scientific management system and combining them with green prevention and control and ecological agriculture concepts can we achieve the long-term goal of "improving quality and efficiency, reducing quantity and controlling pests".
