Data from: An alternative pathway to eusociality: exploring the molecular and functional basis of fortress defense

Some animals express a form of eusociality known as 'fortress defense', in which defense rather than brood care is the primary social act. Aphids are small plant-feeding insects, but like termites, some species express division of labor and castes of aggressive juvenile 'soldiers'. What is the functional basis of fortress defense eusociality in aphids? Previous work showed that the acquisition of venoms might be a key innovation in aphid social evolution. We show that the lethality of aphid soldiers derives in part from the induction of exaggerated immune responses in insects they attack. Comparisons between closely-related social and non-social species identified a number of secreted effector molecules that are candidates for immune modulation, including a convergently-recruited protease described in unrelated aphid species with venom-like functions. These results suggest that aphids are capable of antagonizing conserved features of the insect immune response, and provide new insights into the mechanisms underlying the evolution of fortress defense eusociality in aphids.

部分动物展现出一种被称为"堡垒防御型"（fortress defense）的真社会性（eusociality）形式，其核心社会行为为防御而非育幼。蚜虫（Aphids）作为小型植食性昆虫，与白蚁类似，部分物种演化出了劳动分工体系以及具有攻击性行为的幼年"士兵"品级。蚜虫的堡垒防御型真社会性，其功能基础究竟为何？

既往研究表明，毒液的获得或许是蚜虫社会演化进程中的一项关键创新。本研究发现，蚜虫"士兵"的致死性部分源于其诱导了被攻击昆虫的过度免疫反应。通过对亲缘关系相近的社会性与非社会性物种开展比较分析，研究团队鉴定出多种可作为免疫调节候选靶点的分泌型效应分子，其中包括在无亲缘关系的蚜虫物种中被发现的、具有毒液样功能的趋同招募的蛋白酶。

上述结果表明，蚜虫能够拮抗昆虫免疫反应的保守特征，同时为解析蚜虫堡垒防御型真社会性的演化机制提供了全新视角。