Chowdhury Ritabrata, Grafe T Ulmar, Metali Faizah, Federle Walter
Department of Zoology, University of Cambridge, Cambridge, Cambridgeshire, UK.
Faculty of Science, Universiti Brunei Darussalam, Bandar Seri Begawan, Brunei-Muara District, Brunei Darussalam.
Biol Lett. 2025 Jun;21(6):20250005. doi: 10.1098/rsbl.2025.0005. Epub 2025 Jun 6.
The coevolution of insects and chemical plant defences has been described as an arms race, but it is unclear whether physical plant defences can produce similar outcomes. Here, we report a previously unknown interaction from the mutualism between ants and trees. Although trees are well protected against herbivory by aggressive ants, caterpillars of the genus (Lepidoptera: Lycaenidae) can feed on the leaves by appeasing the ants with nectar-like secretions. One ant-plant species, , bears hooked trichomes on its green surfaces. When placed on stems or petioles, caterpillars associated with other species ( and ) were quickly arrested by the sharp trichomes that pierced their cuticle, resulting in death by rapid blood loss and removal by ants. In striking contrast, caterpillars, which occur naturally on , could easily walk over the hooked trichomes without any injury. As hooked trichomes are a novel trait within , this interaction provides an example of de novo evolution of a physical plant defence, which in turn has been overcome by a specialist herbivore. Our study suggests that physical plant defences can lead to evolutionary arms races similar to those for chemical defences.
昆虫与植物化学防御的共同进化被描述为一场军备竞赛，但尚不清楚植物的物理防御是否会产生类似的结果。在这里，我们报告了一种此前未知的蚂蚁与树木之间互利共生的相互作用。尽管树木受到具有攻击性的蚂蚁的良好保护，免受食草动物侵害，但某属（鳞翅目：灰蝶科）的毛虫可以通过分泌类似花蜜的物质安抚蚂蚁，从而取食树叶。一种蚁栖植物在其绿色表面带有钩状毛状体。当与其他物种（和）相关的毛虫被放置在该植物的茎或叶柄上时，尖锐的毛状体很快就会刺穿它们的表皮，导致它们因快速失血而死亡，并被蚂蚁搬走。形成鲜明对比的是，自然生长在该植物上的毛虫能够轻松地从钩状毛状体上走过而不受任何伤害。由于钩状毛状体是该植物中的一种新特征，这种相互作用提供了一个植物物理防御从头进化的例子，而这种防御反过来又被一种专食性食草动物克服。我们的研究表明，植物的物理防御能够导致类似于化学防御的进化军备竞赛。
