Supplementary Material for: How Not to Be Turned into a Zombie

The emerald jewel wasp (<i>Ampulex compressa</i>) is renowned for its ability to zombify the American cockroach (<i>Periplaneta americana</i>) with a sting to the brain. When the venom takes effect, the cockroach becomes passive and can be led by its antenna into a hole, where the wasp deposits an egg and then seals the exit with debris. The cockroach has the ability to walk, run, or fly if properly stimulated, but it does not try to escape as it is slowly eaten alive by the developing wasp larva. Although the composition and effects of the wasp’s venom have been investigated, no studies have detailed how cockroaches might prevent this grim fate. Here it is shown that many cockroaches deter wasps with a vigorous defense. Successful cockroaches elevated their bodies, bringing their neck out of reach, and kicked at the wasp with their spiny hind legs, often striking the wasp’s head multiple times. Failing this, the elevated, “on-guard” position allowed cockroaches to detect and evade the wasp’s lunging attack. If grasped, the cockroaches parried the stinger with their legs, used a “stiff-arm” defense to hold back the stinger, and could stab at, and dislodge, the wasp with tibial spines. Lastly, cockroaches bit at the abdomen of wasps delivering the brain sting. An aggressive defense from the outset was most successful. Thus, for a cockroach not to become a zombie, the best strategy is: be vigilant, protect your throat, and strike repeatedly at the head of the attacker.

翡翠扁头泥蜂（Ampulex compressa）以其通过蜇刺大脑将美洲大蠊（Periplaneta americana）僵尸化的能力而闻名。当毒液起效后，美洲大蠊会进入被动状态，可被其触角牵引至洞穴中，泥蜂会在此处产卵，随后用杂物封堵洞穴出口。即便美洲大蠊在适当刺激下仍可行走、奔跑或飞行，但当发育中的泥蜂幼虫将其缓慢活食时，它并不会尝试逃脱。尽管学界已对该泥蜂毒液的成分与作用效果展开研究，但目前尚无相关研究详细阐明美洲大蠊可通过何种方式避免这一悲惨命运。本研究证实，诸多美洲大蠊可通过积极防御击退泥蜂。成功抵御的个体通常会抬高身体，使颈部脱离泥蜂的攻击范围，并用带有尖刺的后足踢击泥蜂，往往能多次击中泥蜂头部。若未能成功规避，这种抬起身体的“警戒姿态”可让美洲大蠊及时察觉并躲开泥蜂的突袭。若被泥蜂抓住，美洲大蠊会用腿部格挡蜇针，通过“伸臂防御”抵住蜇针，还可利用胫节尖刺刺击并驱离泥蜂。此外，美洲大蠊还会撕咬实施大脑蜇刺的泥蜂腹部。从一开始就发起主动防御的成功率最高。因此，若美洲大蠊不想沦为僵尸，最佳策略为：保持警惕、保护颈部，并反复击打攻击者的头部。