在鱼虾蟹等水产品病害防治中,由于我们长期、反复使用同一种药物或同一类药物而引起病原产生抗药性,治疗效果下降或无效,导致药物用量越来越大,防治次数越来越频繁,所用药物也越来越高档。几年前治疗鱼类寄生虫,用90%以上晶体敌百虫0.3ppm~0.5ppm就可以,而现在用量达到1ppm,有 In the prevention and treatment of aquatic diseases such as fish, shrimp and crabs, the long-term and repeated use of the same drug or the same kind of drugs causes the drug resistance of the pathogen, and the therapeutic effect is reduced or ineffective, resulting in the increasing dosage of drugs and increasing control times Frequent, the drugs used are more and more upscale. A few years ago the treatment of fish parasites, with more than 90% crystalline trichlorfon 0.3ppm ~ 0.5ppm can, and now the amount reached 1ppm, there