该文对近年来褐稻虱迁入虫源的性质进行了探讨，结果表明迁入的虫源在鉴别品种Ｍｕｄｇｏ上的致害力，生存率、取食量和原始的种群生物型Ⅰ没有明显的差别；两者在酯酶同工酶谱带数目和ＲＦ值也没有差异。迁入的虫源在田间抗性品种上明显表现虫量少。因此，迁入江淮稻区虫源仍是种群生物型Ⅰ。人工在Ｍｕｄｇｏ上诱导产生的生物型Ⅱ再回到感性品种上连续饲养８代，其对Ｍｕｄｇｏ的致害性降为１．０级，表明了褐稻虱生物型的不稳定性。 In this paper, the characteristics of immigrant brown planthopper inoculated with brown planthopper in recent years were discussed. The results showed that there was no significant difference in the virulence, survival rate, The difference between the two in the esterase isozyme band number and RF value is no difference. The migratory insects apparently show less insects on the field resistant varieties. Therefore, migrating to Jianghuai rice area is still the source of species Ⅰ. The biotype II induced by artificial induction on Mudgo was returned to the susceptible cultivar and maintained for 8 generations continuously. Its lethality to Mudgo reduced to 1.0, indicating the instability of the brown planthopper biotype.