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多胚发育的幼虫内寄生蜂腰带长体茧蜂Macrocentrus cingulum的卵、胚胎和幼虫在寄主亚洲玉米螟Ostrinia furnacalis幼虫血腔内发育,通常1枚卵可以分裂增殖为数百只胚胎。本文通过定时解剖寄生的寄主幼虫,初步了解了腰带长体茧蜂多胚的形成过程及其在寄主体内的发育情况。结果表明:以4龄末期亚洲玉米螟幼虫为寄主时,寄生蜂卵产入寄主体内10min左右开始卵裂,1天左右,初级胚胎从卵壳中被释放出来。之后胚胎在胚外膜内持续分裂产生大量二级胚胎形成桑葚胚。寄生后3天左右,二级胚胎从胚外膜中被释放出来,进入胚胎发育阶段。寄生后6天左右,胚胎进入胚带形成阶段。寄生后8天左右,胚带伸长,头尾形成。寄生后9天左右,身体分节完成,部分幼虫孵化,蜕去胚外膜。寄生后13天左右,蜂幼虫从寄主体内啮出。胚胎在发育初期体积变化不大,但从胚带形成开始,体积则迅速增大。腰带长体茧蜂与另一多胚发育寄生蜂佛州点缘跳小蜂Copidosoma floridanum在胚胎发育进程上明显不同,体现了它们对各自寄主的适应。
Multi-embryo development larvae Internal parasitoid larvae Egg, embryo and larvae of the Macrocentrus cingulum develop in the blood cavity of the larvae of the host Ostrinia furnacalis. Usually, one egg can divide and proliferate into hundreds of embryos. In this paper, the larvae of parasitized host larvae were dissected periodically to understand the formation process of polyembryonic embryo and its development in the host. The results showed that when the Asian corn borer larvae were hosted at the end of the fourth instar stage, the parasitic wasp eggs began to enter the host within about 10 minutes to begin cleavage. After about one day, the primary embryos were released from the egg shell. After the embryos continue to divide in the outer membrane to produce a large number of secondary embryos forming morula. About three days after the parasitism, secondary embryos are released from the extraembryonic membrane and enter the embryonic development stage. About 6 days after the parasitosis, the embryo enters the stage of embryogenesis. About 8 days after parasitism, embryo belt elongation, head and tail formation. About 9 days after the parasitism, the body section completed, part of the larvae hatch, shed the outer membrane. About 13 days after parasitization, bee larvae feed from the host. The volume of the embryo did not change much at the early stage of development, but the volume increased rapidly from the formation of the embryo. Copdosoma floridanum, a parasitoid that develops into a parasitoid with another polyembryony, is significantly different in embryonic development and reflects their adaptation to their respective host.