农药Pesticide

有机磷（如敌敌畏）和氨基甲酸酯杀虫剂抑制乙酰胆碱酯酶，使害虫神经持续兴奋而死；拟除虫菊酯作用于钠离子通道；新烟碱类（如吡虫啉）作用于烟碱型乙酰胆碱受体。除草剂草甘膦抑制植物特有的 EPSP 合酶，阻断芳香族氨基酸合成；三唑类杀菌剂抑制真菌麦角甾醇生物合成。

Organophosphate (such as dichlorvos) and carbamate insecticides inhibit acetylcholinesterase, leaving the insect's nerves permanently firing; pyrethroids act on sodium channels; neonicotinoids such as imidacloprid act on nicotinic acetylcholine receptors. The herbicide glyphosate blocks the plant enzyme EPSP synthase and with it aromatic amino-acid synthesis; triazole fungicides block ergosterol biosynthesis in fungi.

早期农药是硫磺、砷化合物、波尔多液（1885 年，硫酸铜与石灰）和烟草、除虫菊等植物提取物。1939 年 DDT 的杀虫性能被发现，开启了有机合成农药时代；1940 年代出现有机磷和除草剂 2,4-D。1962 年《寂静的春天》引发对环境危害的反思。此后农药向高效低毒低残留发展，如拟除虫菊酯（1970 年代）、磺酰脲类除草剂和生物农药。

Early pesticides were sulfur, arsenic compounds, Bordeaux mixture (1885, copper sulfate with lime) and plant extracts such as tobacco and pyrethrum. The discovery of DDT's insecticidal power in 1939 opened the era of synthetic organic pesticides, followed in the 1940s by organophosphates and the herbicide 2,4-D. Silent Spring (1962) prompted a reckoning with environmental harm, and development turned to potent, low-toxicity, low-residue products such as synthetic pyrethroids (1970s), sulfonylurea herbicides and biopesticides.

农药残留、害虫抗药性、对蜜蜂和水生生物的毒性是主要问题。各国规定最大残留限量和安全间隔期，高毒农药如甲胺磷、对硫磷已在中国禁用。综合防治（IPM）主张把生物防治、农业措施与精准施药结合，减少用量。

The main concerns are residues on food, pest resistance and toxicity to bees and aquatic life. Countries set maximum residue limits and pre-harvest intervals, and highly toxic products such as methamidophos and parathion are banned in China. Integrated pest management (IPM) combines biological control, cultural practices and precise application to cut use.