Although calcareous anatomical structures have evolved in diverse animal groups, such structures have been unknown in insects. Here, we report the discovery of high-magnesium calcite [CaMg(CO₃)₂] armor overlaying the exoskeletons of major workers of the leaf-cutter ant Acromyrmex echinatior. Live-rearing and in vitro synthesis experiments indicate that the biomineral layer accumulates rapidly as ant workers mature, that the layer is continuously distributed, covering nearly the entire integument, and that the ant epicuticle catalyzes biomineral nucleation and growth. In situ nanoindentation demonstrates that the biomineral layer significantly hardens the exoskeleton. Increased survival of ant workers with biomineralized exoskeletons during aggressive encounters with other ants and reduced infection by entomopathogenic fungi demonstrate the protective role of the biomineral layer. The discovery of biogenic high-magnesium calcite in the relatively well-studied leaf-cutting ants suggests that calcareous biominerals enriched in magnesium may be more common in metazoans than previously recognized.

尽管钙的解剖结构已经在不同的动物群体中进化，但是在昆虫中这种结构是未知的。在这里，我们报告了发现高镁方解石[CaMg（CO ₃）₂ ]装甲覆盖在切叶蚁Acromyrmex echinatior的主要工人的外骨骼上的发现。饲养和体外合成实验表明，随着蚂蚁工人的成熟，生物矿物质层会迅速积累，该矿物质层是连续分布的，几乎覆盖了整个被膜，并且蚂蚁表皮催化了生物矿物质的成核和生长。原位纳米压痕表明生物矿物质层显着硬化了外骨骼。在与其他蚂蚁进行激烈接触期间，具有生物矿化外骨骼的蚂蚁工人的存活率提高，而昆虫病原真菌的感染减少，这证明了生物矿物质层的保护作用。在研究相对较好的切叶蚂蚁中发现了生物源性高镁方解石，这表明富含镁的钙质生物矿物在后生动物中可能比以前认识的更为普遍。