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推广抗虫品种,是害虫综合防治中一项既经济有效,又安全简便的措施。但是,在抗虫品种推广后,有时出现抗虫性减退或丧失的现象。产生此现象的原因有二:(1)由于生态条件的差异,分布在不同地区的同一种害虫在取食的适应性上有所不同,即形成了不同的生物型。所以在一个地区表现抗虫的品种,推广到另一个地区有可能变成感受品种。(2)在一个地区推广抗虫品种后,原来占优势的害虫某生物型受到了淘汰。但由于遗传差异,发生数量不多的
Popularization of insect-resistant varieties is a cost-effective and safe and easy measure for integrated pest management. However, after the popularization of the insect-resistant varieties, there is a case that the insect resistance is diminished or lost. There are two reasons for this phenomenon: (1) Due to the difference in ecological conditions, the same pests distributed in different regions have different adaptability in feeding, that is, different biotypes are formed. Therefore, the performance of insect-resistant varieties in one area, spread to another area may become a feeling of variety. (2) After the popularization of the insect-resistant varieties in one area, some biotypes of the predominant pests have been eliminated. However, due to genetic differences, a small number occur