Data from: No evidence for social immunity in co-founding queen associations

Ant queens often associate to found new colonies, yet the benefits of this behaviour remain unclear. A major hypothesis is that queens founding in groups are protected by social immunity and can better resist disease than solitary queens, due to mutual grooming, sharing of antimicrobials, or higher genetic diversity among their workers. We tested this hypothesis by manipulating the number of queens in incipient colonies of Lasius niger and measuring their resistance to the fungal entomopathogen Metarhizium brunneum. We found no evidence for social immunity in associations of founding queens. First, co-founding queens engaged in self-grooming, but performed very little allo-grooming or trophallaxis. Second, co-founding queens did not exhibit higher pathogen resistance than solitary queens, and their respective workers did not differ in disease resistance. Finally, queens founding in groups increased their investment in a component of individual immunity, as expected if they do not benefit from social immunity but respond to a higher risk of disease. Overall, our results provide no evidence that joint colony founding by L. niger queens increases their ability to resist fungal pathogens.

蚁后常结伴建立新蚁群，但该行为的益处尚未明晰。其中一项主流假说指出，集群建群的蚁后可通过社会免疫（social immunity）获得保护，相较独居蚁后更能抵御病害——这一优势源于彼此梳理、共享抗菌物质，或是其工蚁群体具备更高的遗传多样性。我们通过调控黑毛蚁（Lasius niger）初始蚁群中的蚁后数量，并测定其对昆虫病原真菌布鲁氏绿僵菌（Metarhizium brunneum）的抗性，对该假说开展了验证。我们并未发现结伴建群的蚁后存在社会免疫效应的相关证据：其一，结伴建群的蚁后仅进行自我梳理，几乎不会开展异体梳理或交哺行为；其二，结伴建群的蚁后的病原抗性并未优于独居蚁后，且二者所抚育的工蚁在病害抗性上亦无显著差异；最后，集群建群的蚁后会提升个体免疫相关组分的投入——这契合了它们无法从社会免疫中获益、但需应对更高病害风险的预期。综上，本研究结果并未表明黑毛蚁蚁后结伴建群能够提升其抵御真菌病原的能力。