What are the Mechanisms Behind a Parasite-Induced Decline in Nestmate Recognition in Ants?
What are the Mechanisms Behind a Parasite-Induced Decline in Nestmate Recognition in Ants?
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DOI：
10.1007/s10886-017-0880-6
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发表时间：
2017-09-01
影响因子：
2.3
通讯作者：
Menzel, Florian
中科院分区：
文献类型：
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作者：
Beros, Sara;Foitzik, Susanne;Menzel, Florian
群居昆虫已经发展出复杂的识别技能来保护它们的巢穴免受入侵者的侵害。他们通过积极歧视具有异常表皮碳氢化合物（CHC）特征的非巢穴来做到这一点。研究巢友识别可能具有挑战性，因为个体昆虫不仅在辨别能力上存在差异，而且在攻击性行为的动机上也存在差异。为了阐明信号和行为动机对同窝识别的影响，我们研究了尼兰德里蚂蚁，感染绦虫的同窝蚂蚁的存在会导致未感染工蚁的同窝识别减少。寄生虫引起的巢友识别能力下降可能是由于较高的群体内线索多样性引起的，因为已知感染绦虫的工蜂会表现出改变的碳氢化合物特征。这反过来可能会拓宽其巢友的神经元模板，从而导致对外来同种动物具有更高的耐受性。为了检验这一假设，我们在蚁群之间交换了受感染的蚂蚁，并分析了它们对未受感染工蚁 CHC 特征的影响。我们证明，尽管频繁的梳理应该促进识别线索的转移，但未感染工蚁的 CHC 特征在感染绦虫的蚂蚁存在时既没有改变，也没有增加蚁群内或蚁群之间未感染蚁巢的线索多样性。然而，CHC 谱受到巢友的移除和非巢友的添加的系统性影响，与蚂蚁的感染状态无关。例如，当非同巢动物在场时，工蚁会表达出更多的二甲基烷烃和更高的 CHC 总量，这可能是为了更好地与非同巢动物区分开来。工人们表现出清晰的特定任务特征，感染绦虫的工人们更像是年轻的护士，而不是年长的觅食者。我们的研究结果表明，寄生虫引起的巢友识别能力下降并不是由于识别线索多样性增加或未感染工蜂的 CHC 配置文件改变，而是行为变化可能解释了对入侵者的耐受性。
Social insects have developed sophisticated recognition skills to defend their nests against intruders. They do this by aggressively discriminating against non-nestmates with deviant cuticular hydrocarbon (CHC) signatures. Studying nestmate recognition can be challenging as individual insects do not only vary in their discriminatory abilities, but also in their motivation to behave aggressively. To disentangle the influence of signaling and behavioral motivation on nestmate recognition, we investigated the ant Temnothorax nylanderi, where the presence of tapeworm-infected nestmates leads to reduced nestmate recognition among uninfected workers. The parasite-induced decline in nestmate recognition could be caused by higher intra-colonial cue diversity as tapeworm-infected workers are known to exhibit a modified hydrocarbon signature. This in turn may broaden the neuronal template of their nestmates, leading to a higher tolerance towards alien conspecifics. To test this hypothesis, we exchanged infected ants between colonies and analyzed their impact on CHC profiles of uninfected workers. We demonstrate that despite frequent grooming, which should promote the transfer of recognition cues, CHC profiles of uninfected workers neither changed in the presence of tapeworm-infected ants, nor did it increase cue diversity among uninfected nestmates within or between colonies. However, CHC profiles were systematically affected by the removal of nestmates and addition of non-nestmates, independently from the ants' infection status. For example, when non-nestmates were present workers expressed more dimethyl alkanes and higher overall CHC quantities, possibly to achieve a better distinction from non-nestmates. Workers showed clear task-specific profiles with tapeworm-infected workers resembling more closely young nurses than older foragers. Our results show that the parasite-induced decline in nestmate recognition is not due to increased recognition cue diversity or altered CHC profiles of uninfected workers, but behavioral changes might explain tolerance towards intruders.