Data from: Lock-picks: fungal infection facilitates the intrusion of strangers into ant colonies

Studies investigating host-parasite systems rarely deal with multispecies interactions, and mostly explore impacts on hosts as individuals. Much less is known about the effects at colony level, when parasitism involves host organisms that form societies. We surveyed the effect of an ectoparasitic fungus, Rickia wasmannii, on kin-discrimination abilities of its host ant, Myrmica scabrinodis, identifying potential consequences at social level and subsequent changes in colony infiltration success of other organisms. Analyses of cuticular hydrocarbons (CHCs), known to be involved in insects’ discrimination processes, revealed variations in chemical profiles correlated with the infection status of the ants, that could not be explained by genetic variation tested by microsatellites. In behavioural assays, fungus-infected workers were less aggressive towards both non-nestmates and unrelated queens, enhancing the probability of polygyny. Likewise, parasitic larvae of Maculinea butterflies had a higher chance of adoption by infected colonies. Our study indicates that pathogens can modify host recognition abilities, making the society more prone to accept both conspecific and allospecific organisms.

针对宿主-寄生物系统的研究极少涉及多物种互作，且大多仅探讨寄生物对单个宿主的影响。而当寄生物的宿主为具有社会属性的类群时，学界对该寄生作用在群体层面产生的效应则知之甚少。本研究针对外寄生真菌（ectoparasitic fungus）Rickia wasmannii对其宿主蚂蚁Myrmica scabrinodis的亲缘识别能力展开调查，同时解析该寄生作用在社会层面的潜在后果，以及其他生物入侵宿主蚁群成功率的后续变化。针对已知参与昆虫识别过程的表皮碳氢化合物（cuticular hydrocarbons, CHCs）的分析显示，蚂蚁的化学信号谱存在与感染状态相关的变异，且该变异无法通过微卫星（microsatellites）检测到的遗传差异予以解释。在行为测定实验中，感染真菌的工蚁对非巢伴以及无亲缘关系的蚁后均表现出更低的攻击性，这提升了蚁群形成多后制的概率。同样，Maculinea蝴蝶的寄生幼虫被感染蚁群接纳的概率更高。本研究表明，病原微生物可改变宿主的识别能力，使得宿主社会更易接纳同种及异种生物。