simulation_data.csv from Temporary prey storage along swarm columns of army ants: an adaptive strategy for successful raiding?

While pillaging the brood of other ant colonies, <i>Eciton</i> army ants accumulate prey in piles, or caches, along their foraging trails. Widely documented, these structures have historically been considered as by-products of heavy traffic or aborted relocations of the ants' temporary nest, or bivouac. However, we recently observed that caches of the hook-jawed army ant, <i>Eciton hamatum</i>, appeared independently from heavy traffic or bivouac relocations. In addition, the flow of prey through caches varied based on the quantity of prey items workers transported. As this suggested a potential adaptive function, we developed agent-based simulations to compare raids of caching and non-caching virtual army ants. We found that caches increased the amount of prey that relatively low numbers of raiders were able to retrieve. However, this advantage became less conspicuous—and generally disappeared—as the number of raiders increased. Based on these results, we hypothesize that caches maximize the amount of prey that limited amounts of raiders can retrieve, especially as prey colonies coordinately evacuate their brood. In principle, caches also allow workers to safely collect multiple-prey items and efficiently transport them to the bivouac. Further field observations are needed to test this and other hypotheses emerging from our study.

在劫掠其他蚁群幼虫的过程中，行军蚁属（*Eciton*）的行军蚁会沿着觅食路径将猎物堆积成堆，即储藏点（caches）。这类结构已被广泛记录，以往学界一直将其视为蚁群密集通行的副产品，或是其临时宿营巢（bivouac）迁址中断的产物。然而我们近期观察到，钩颚行军蚁（*Eciton hamatum*）的储藏点并非由密集通行或宿营巢迁址所催生，而是独立形成的。此外，经由储藏点的猎物流量会随工蚁转运的猎物数量变化而改变。鉴于这一现象提示储藏点可能具备适应性功能，我们开发了基于智能体的模拟模型，对比了拥有储藏点与无储藏点的虚拟行军蚁的劫掠行为。研究发现，当劫掠者数量相对较少时，储藏点能够提升可回收的猎物总量；但随着劫掠者数量增加，这一优势会逐渐减弱，最终通常完全消失。基于上述结果，我们提出假说：当有限数量的劫掠者参与行动时，尤其是在猎物种群协同疏散幼虫的场景下，储藏点能够最大化可回收的猎物总量。理论上，储藏点还能让工蚁安全收集多份猎物，并高效地将其转运至临时宿营巢。后续仍需开展野外观察，以验证本研究提出的这一假说及其他相关衍生假说。