Supplementary Material for: Getting the Most Out of Your Zombie: Abdominal Sensors and Neural Manipulations Help Jewel Wasps Find the Roach’s Weak Spot

The parasitoid emerald jewel wasp (Ampulex compressa) subdues the American cockroach (Periplaneta americana) with a sting to the 1st thoracic ganglion, followed by a sting to the roach’s brain, causing long-term pacification. The wasp then leads the cockroach to a hole where it lays an egg on the roach middle leg before barricading the entrance and departing. Although many aspects of the wasp’s initial attack have been investigated, few studies have detailed the egg-laying process and the subsequent fate of the larvae. Here I show that larval survival depends on precise egg positioning on the cockroach by the female wasp. Ablation of sensory hairs on the wasp’s abdomen resulted in mislaid eggs, which seldom survived. In addition, the cockroach femur may block the oviposition site. The wasp contended with this challenge with a newly discovered suite of stings, 3 directed into the 2nd thoracic ganglion which resulted in extension of the femur, thus exposing the oviposition site and removing a potential barrier to the wasp’s successful reproduction. When the femur was glued in place, the wasp stung the cockroach over 100 times, in an apparent fixed action pattern triggered by the obscured oviposition target. These findings highlight the importance of proper egg placement by the wasp, and reveal sensors and new neural manipulations that facilitate the process.

寄生性绿宝石扁头泥蜂（Ampulex compressa）可通过蛰刺美洲大蠊（Periplaneta americana）的第一胸神经节（1st thoracic ganglion），随后蛰刺其脑部，实现长期镇静效应。该蜂随后会将美洲大蠊引导至洞穴中，在其中足上产卵，之后封堵洞口并离开。尽管学界已对该蜂初始攻击环节的诸多方面展开研究，但鲜有文献详细阐述其产卵过程及幼虫的后续存活命运。本研究表明，幼虫的存活率取决于雌蜂在美洲大蠊体表进行精准产卵定位的能力。切除雌蜂腹部的感觉毛（sensory hairs）会导致产卵位置偏差，此类异常产卵的卵极少能够存活。此外，美洲大蠊的股骨可能会遮挡产卵位点（oviposition site）。针对这一难题，该蜂借助一套新近发现的蛰刺行为组合：三次蛰刺第二胸神经节（2nd thoracic ganglion），可促使股骨伸展，从而暴露产卵位点，消除其成功繁殖的潜在障碍。当美洲大蠊的股骨被固定无法移动时，该蜂会对其重复蛰刺超过100次，这显然是由被遮挡的产卵目标触发的固定动作模式（fixed action pattern）。本研究结果既凸显了雌蜂精准产卵定位的重要性，同时也揭示了助力该产卵过程的感觉器官与全新神经调控机制。