Data from: Wood ants produce a potent antimicrobial agent by applying formic acid on tree-collected resin

Wood ants fight pathogens by incorporating tree resin with antimicrobial properties into their nests. They also produce large quantities of formic acid in their venom gland, which they readily spray to defend or disinfect their nest. Mixing chemicals to produce powerful antibiotics is common practice in human medicine, yet evidence for the use of such “defensive cocktails” by animals remains scant. Here, we test the hypothesis that wood ants enhance the antifungal activity of tree resin by treating it with formic acid. In a series of experiments, we document that (i) tree resin had much higher inhibitory activity against the common entomopathogenic fungus Metarhizium brunneum after having been in contact with ants, while no such effect was detected for other nest materials; (ii) wood ants applied significant amounts of endogenous formic and succinic acid on resin and other nest materials; and (iii) the application of synthetic formic acid greatly increased the antifungal activity of resin, but had no such effect when applied to inert glass material. Together, these results demonstrate that wood ants obtain an effective protection against a detrimental microorganism by mixing endogenous and plant-acquired chemical defenses. In conclusion, the ability to synergistically combine antimicrobial substances of diverse origins is not restricted to humans and may play an important role in insect societies.林蚁（Wood ants）会将具备抗菌特性的树树脂纳入巢穴，以此抵御病原体。它们还会在毒腺（venom gland）中生成大量甲酸（formic acid），并可随时喷射该物质以保卫巢穴或对其进行消毒。在人类医学领域，混合化学物质以制备强效抗生素是常规操作，但动物使用这类"防御鸡尾酒"的相关证据仍极为匮乏。本研究旨在验证下述假说：林蚁可通过甲酸处理树树脂，从而增强其抗真菌活性。通过一系列实验，我们证实：(i) 与林蚁接触后的树树脂，对常见昆虫病原真菌（entomopathogenic fungus）布氏白僵菌（Metarhizium brunneum）的抑制活性显著提升，而其他巢穴材料未表现出此类效应；(ii) 林蚁会在树树脂及其他巢穴材料上涂抹大量内源性甲酸与琥珀酸（succinic acid）；(iii) 施加合成甲酸可显著提升树树脂的抗真菌活性，但将其施加于惰性玻璃材料时则无此效果。综合上述结果可知，林蚁可通过混合内源性与植物来源的化学防御物质，有效抵御有害微生物。综上，协同结合不同来源抗菌物质的能力并非人类独有，这一能力或许在昆虫社会中发挥着重要作用。