Individual and collective decision making and risk evaluation in slavemaking ants

群居昆虫的群体是合作决策和集体智慧的最好例子。在人类社会的组织中，决策通常由一个或几个特定的个体做出，与此相反，蚂蚁社会的决策基于简单的经验法则，每个蚂蚁都要注意。为了使这种分散的过程发挥作用，所有人都必须能够获得相关信息，以做出适应性决策。产奴蚁是专性的社会寄生虫，完全依赖于它们的奴隶，异种工蚁，完成所有日常的殖民任务。它们的繁殖成功率以及社会寄生虫群体的适应性直接取决于寄生虫群体中奴隶的数量。奴隶是通过定期的奴隶袭击获得的，这对奴隶制造者来说本身就是危险的任务：大约10%的寄生工人在袭击过程中严重受伤或死亡。决定攻击哪一个宿主蚁群是至关重要的，寻找新宿主蚁群的侦察蚁在招募巢友进行攻击之前，应该仔细权衡风险和收益。早期的研究表明，寄生虫群体--当有选择的时候--确实更喜欢攻击防御不那么好的宿主物种的群体，并根据受害者宿主巢穴的大小来调整袭击方中寄生虫工人的数量。在这里，我们计划调查的风险评估和决策，在两个奴隶制的蚂蚁物种，这代表了独立的起源奴隶制和不同的平均殖民地大小。我们希望集中在侦察蚁的个体决策和寄生蚁群的集体决策上，即是否对给定的宿主巢穴发起攻击。这些决定的重要性是关于潜在的受害群体和寄生虫群体的条件的信息，这些信息必须由寄生虫群体成员获得、分发和评估。

Colonies of social insects are prime examples for cooperative decision making and collective intelligence. In contrast to the organisation of human societies where decisions are often made by one or few specially assigned individuals, decisions in ant societies are based on simple rules of thumb, heeded by each ant. For this kind of decentralized processes to work, all individuals must have access to relevant information to make adaptive decisions. Slavemaking ants are obligate social parasites that completely rely upon their slaves, allospecific workers, for all routine colony tasks. Their reproductive success and thus the fitness of a social parasite colony directly depend on the number of slaves found in a parasite colony. Slaves are obtained via regular slave raids, which are in itself risky tasks for the slavemakers: around 10% of the parasite workers involved in a raid are severely injured or killed during the process. The decision which host colony to attack is so crucial and scout ants searching for new host colonies should weigh risks and benefits carefully before recruiting nest mates for an attack. Earlier studies showed that parasite colonies - when given a choice - indeed prefer to attack colonies of less well defended host species and adjust the number of parasite workers in a raiding party to victim host nest size. Here, we plan to investigate risk evaluation and decision making in two slavemaking ant species, which represent independent origins of slavery and differ in average colony size. We want to focus on individual decisions made by scout ants and on collective ones of parasite colonies on whether or not to initiate an attack on a given host nest. Important for these decisions are information on the potential victim colony and on the condition of the parasite colony, which has to be obtained, distributed and evaluated by parasite colony members.