寄生不同虫龄小菜蛾对菜蛾啮小蜂生物学特性的影响

以小菜蛾重要的幼虫-蛹跨期寄生蜂菜蛾啮小蜂为研究对象,在(25±1)℃条件下研究了1,2,3,4龄初和4龄末小菜蛾幼虫被寄生后,对菜蛾啮小蜂生物学特性的影响.结果表明,寄生各个虫龄小菜蛾的啮小蜂从卵到羽化的发育历期、羽化后成蜂寿命没有明显的差异.不同虫龄被寄生小菜蛾羽化出的啮小蜂的性比只在3龄末和4龄末之间存在显著性差异,寄生4龄末小菜蛾育出的雄蜂比例最高.菜蛾啮小蜂对各虫龄小菜蛾幼虫产卵寄生没有表现出明显的偏好性,但相比2龄和4龄小菜蛾幼虫,3龄末小菜蛾幼虫仍是较适合的寄主,寄生3龄末小菜蛾幼虫羽化出的啮小蜂个体最大.

Effects of host instar on biological characters of Oomyzus sokolowskii, a larval-pupal parasitoid of Plutella xylostella

Investigation was conducted on the effects of different host instar and size on biological char-acters of Oomyzus sokolowskii (Kurdjumov) , an important larval-pupal endoparasitoid of Plutella xylos-tella L. in the laboratory at (25±1 )℃.. The results showed that parasitoids developing in different host instars did not exhibit significant differences in development time, and adult longevity was almost the same. The proportion of male wasps that emerged from the late fourth instar hosts was significantly higher than that the late third instar larvae. In choice experiment, the wasp did not show any prefer-ence to the four larval instars, indicating almost the same host suitability among different larval instars. However, the late third instar larvae was the most suitable host compared with the other instars for par-asitoid because the biggest wasp emerged from them.