一种农药在同一种害虫上反复使用,经过一定时间以后,药效明显减退,甚至不再有效的现象,称为抗药性。出现抗药性后,如果单纯采取加大施药浓度、增加喷药次数的办法,不仅浪费农药,增加成本,而且加重了农药的污染,更增强了害虫的抗药性。那么,如何预防害虫的抗药性呢?主要措施是: A pesticide on the same kind of pests repeatedly used, after a certain period of time, the drug efficacy decreased significantly, or even no longer valid phenomenon, known as drug resistance. After the emergence of drug resistance, if only to increase the drug concentration, increase the number of spraying methods, not only waste pesticides, increase costs, but also aggravate the pollution of pesticides, but also enhance the resistance of pests. So, how to prevent pest resistance? The main measures are: