Lawson Sarah P, Sigle Leah T, Lind Abigail L, Legan Andrew W, Mezzanotte Jessica N, Honegger Hans-Willi, Abbot Patrick
Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, 37235.
Department of Biological Sciences, University of New Hampshire, Durham, New Hampshire, 03824.
Evolution. 2017 Aug;71(8):1986-1998. doi: 10.1111/evo.13285. Epub 2017 Jun 30.
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 nonsocial 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.
一些动物表现出一种被称为“堡垒防御”的群居形式，其中防御而非育幼是主要的社会行为。蚜虫是小型以植物为食的昆虫，但与白蚁一样，一些物种表现出分工以及具有攻击性的幼年“士兵”等级。蚜虫堡垒防御群居性的功能基础是什么？先前的研究表明，毒液的获得可能是蚜虫社会进化中的一项关键创新。我们发现，蚜虫“士兵”的致死性部分源于它们攻击的昆虫中过度免疫反应的诱导。对亲缘关系密切的群居和非群居物种的比较确定了一些分泌效应分子，它们是免疫调节的候选分子，包括在具有毒液样功能的不相关蚜虫物种中发现的一种趋同招募的蛋白酶。这些结果表明，蚜虫能够对抗昆虫免疫反应的保守特征，并为蚜虫堡垒防御群居性进化的潜在机制提供了新见解。
