小菜蛾是一种世界性分布的十字花科蔬菜主要害虫,目前许多药效试验和昆虫抗性研究中都以小菜蛾幼虫为试验材料。它的成虫性别可直接通过外生殖器而准确地鉴定。用Robertson(1939年)的方法也能鉴别出小菜蛾蛹的性别,但是,用这种方法对小菜蛾幼虫进行雌雄鉴别比较困难。某些研究要求对小菜蛾进行性别鉴定。例如在小菜蛾不同品系间的杂交研究中,则要求同一品系内幼虫按雌雄分组隔离饲养,以避免系内交配。由于小菜蛾 Plutella xylostella is a worldwide pest of cruciferous vegetables. At present, many studies on efficacy and insects resistance use Plutella xylostella as test material. Its adult sex can be accurately identified directly by genitalia. The sex of the diamondback moth pupae can also be identified by the method of Robertson (1939), however, it is more difficult to discriminate the male and female diamondback moth larvae by this method. Some studies require sex determination of Plutella xylostella. For example, in the study of crossbreed between different diamondback moths, it is required that the larvae in the same line be segregated by male and female in order to avoid inbreeding. Because of diamondback moth