Raw sperm viability data and Figure S1 from Impact of immune activation on stored sperm viability in ant queens

Ant queens mate on a single occasion early in life and store millions of sperm cells in their spermatheca. By carefully using stored sperm to fertilize eggs, they can produce large colonies of thousands of individuals. Queens can live for decades and their lifetime reproductive success is dependent on their ability to keep stored sperm alive. Maintaining high sperm viability requires metabolic energy which could trade-off with other costly processes such as immunity. We tested the impact of immune activation on the survival of stored sperm by prompting <i>Lasius niger</i> ant queens to mount a melanization response and subsequently measuring sperm viability in their spermatheca. Since queens face different challenges that influence energy allocation depending on the life stage of their colony, we measured sperm viability after immune activation in both newly mated queens (incipient) and in queens 1 year after mating (established). We found that immune activation reduced sperm viability in established queens but not in incipient queens, showing that the cost of immunity on sperm preservation depends on the life stage. Unexpectedly, established queens had significantly higher sperm viability in their spermatheca compared to incipient queens suggesting that ant queens are able to remove dead sperm from their spermatheca.

蚁后在成年早期仅进行一次交配，并将数百万枚精子储存在受精囊（spermatheca）中。通过精准调配储存的精子为卵受精，蚁后可繁衍出拥有数千只个体的庞大蚁群。蚁后的寿命可达数十年，其终生繁殖成功率完全依赖于维持储存精子活性的能力。维持高精子活性需要消耗代谢能量，而这一过程可能与免疫等其他高能耗生理过程存在能量权衡。本研究通过诱导黑毛蚁（Lasius niger）蚁后触发黑化免疫反应，随后检测其受精囊内的精子活性，探究了免疫激活对储存精子存活的影响。鉴于蚁后会根据蚁群的发育阶段面临不同的能量分配挑战，我们分别对初建群蚁后（incipient）以及交配1年的已建群蚁后（established）开展了免疫激活后的精子活性检测。实验结果表明，免疫激活会降低已建群蚁后的精子活性，但对初建群蚁后无显著影响，这说明免疫对精子保存的代谢代价取决于蚁群的发育阶段。出乎意料的是，已建群蚁后的受精囊内精子活性显著高于初建群蚁后，这提示蚁后能够主动清除受精囊内死亡的精子。