The ovipositor actuation mechanism of a parasitic wasp and its functional implications

Parasitic wasps use specialized needle-like structures­­—ovipositors—to drill in substrates to reach hidden hosts. The external ovipositor (terebra) consists of three interconnected, sliding elements (valvulae) which are moved reciprocally during insertion. This presumably reduces the required pushing force on the terebra and limits the risk of damage whilst probing. Although this is an important mechanism, it is still not completely understood how the actuation of the valvulae is achieved, and it has only been studied with the ovipositor in rest position. Additionally, very little is known about the magnitude of the forces generated during probing. We used synchrotron X-ray microtomography to reconstruct the actuation mechanism of the parasitic wasp Diachasmimorpha longicaudata (Braconidae) in four distinct phases of the probing cycle. We show that only the paired first valvulae of the terebra move independently, while the second valvula moves with the metasoma (‘abdomen’). The first v...

寄生蜂利用特化的针状结构——产卵器（ovipositor）——在基质中钻孔以接触隐藏的宿主。外产卵器（terebra）由三个相互连接的滑动元件（valvula）组成，这些元件在插入过程中做往复运动。这一机制推测可降低terebra所需的推力，并在探测时减少损坏风险。尽管这是一个关键机制，但valvula的驱动方式目前仍未完全阐明，且相关研究仅在产卵器处于静止状态下开展。此外，关于探测过程中产生的力的大小，目前所知甚少。我们采用同步辐射X射线显微断层扫描技术，重建了寄生蜂长尾潜蝇茧蜂（Diachasmimorpha longicaudata，茧蜂科）在探测周期四个不同阶段的驱动机制。研究表明，仅terebra中成对的第一valvula能独立运动，而第二valvula则随后体（即“腹部”）一同移动。第一v...