1 Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki , Finland.
2 Tvärminne Zoological Station, Faculty of Biological and Environmental Sciences, University of Helsinki , Finland.
Proc Biol Sci. 2019 Mar 13;286(1898):20182867. doi: 10.1098/rspb.2018.2867.
Temporary social parasite ant queens initiate new colonies by entering colonies of host species, where they begin laying eggs. As the resident queen can be killed during this process, host colonies may lose their entire future reproductive output. Selection thus favours the evolution of defence mechanisms, before and after parasite intrusion. Most studies on social parasites focus on host worker discrimination of parasite queens and their offspring. However, ant larvae can also influence brood composition by consuming eggs. This raises the question whether host larvae can aid in preventing colony takeover by consuming eggs laid by parasite queens. To test whether larvae could play a role in anti-parasite defence, we compared the rates at which larvae of a common host species, Formica fusca, consumed eggs laid by social parasite, non-parasite, nest-mate, or conspecific non-nest-mate queens. Larvae consumed social parasite eggs more than eggs laid by a heterospecific non-parasite queen, irrespective of the chemical distance between the egg cuticular profiles. Also, larvae consumed eggs laid by conspecific non-nest-mate queens more than those laid by nest-mate queens. Our study suggests that larvae may act as players in colony defence against social parasitism, and that social parasitism is a key factor shaping discrimination behaviour in ants.
临时社会性寄生蚁后通过进入宿主物种的蚁群来建立新的蚁群，在那里它们开始产卵。由于在这个过程中，居住的蚁后可能会被杀死，因此宿主蚁群可能会失去它们未来所有的繁殖能力。因此，选择有利于防御机制的进化，无论是在寄生虫入侵之前还是之后。大多数关于社会性寄生虫的研究都集中在宿主工蚁对寄生虫蚁后及其后代的歧视上。然而，蚂蚁幼虫也可以通过消耗卵来影响幼虫的组成。这就提出了一个问题，即宿主幼虫是否可以通过消耗寄生虫蚁后产下的卵来帮助防止蚁群被接管。为了测试幼虫是否可以在抗寄生虫防御中发挥作用，我们比较了一种常见的宿主物种，红火蚁，幼虫消耗社会性寄生虫、非寄生虫、巢内同伴或同种非巢内同伴蚁后产下的卵的速度。幼虫消耗社会性寄生虫卵的速度高于消耗异质非寄生虫蚁后的卵，而与卵的表皮轮廓之间的化学距离无关。此外，幼虫消耗同种非巢内同伴蚁后产下的卵多于巢内同伴蚁后产下的卵。我们的研究表明，幼虫可能是蚁群防御社会性寄生的参与者，而社会性寄生是塑造蚂蚁歧视行为的关键因素。
