Table_1_Trail Pheromone Does Not Modulate Subjective Reward Evaluation in Lasius niger Ants.XLSX

Comparing the value of options is at the heart of economic decision-making. While an option may have an absolute quality (e.g. a food source has a fixed energy content), the perceived value of the option may be malleable. The factors affecting the perceived value of an option may thus strongly influence which option is ultimately chosen. Expectations have been shown to be a strong driver of perceived value in both humans and social insects, causing an undervaluation of a given option if a better option was expected, and an overvaluation if a poorer one was expected. In humans, perceived value can be strongly affected by social information. Value perception in some insects has also been shown to be affected by social information, showing conformism as in humans and other animals. Here, over a series of experiments, we tested whether pheromone trail presence, a social information source, influenced the perceived value of a food source in the ant Lasius niger. We found that the presence of pheromone trails leading to a sucrose solution does not influence food acceptance, pheromone deposition when returning from a food source, drinking time, or frequency of U-turns on return from the food. Two further assays for measuring changes in food acceptance, designed to increase sensitivity by avoiding ceiling effects, also showed no effect of pheromone presence on food acceptance. In a separate study, L. niger have also been found to show no preference for, or avoidance of, odors associated with foods found in the presence of pheromone. We are thus confident that trail pheromone presence does not affect the perceived value of a food source in these ants.

对选项价值的比较是经济决策的核心议题。尽管选项具备绝对属性（例如食物来源拥有固定的能量含量），但该选项的感知价值却具有可塑性。因此，影响选项感知价值的因素，会显著左右最终的决策选择。已有研究表明，预期是影响人类与社会性昆虫感知价值的重要驱动因素：当预期到更优选项时，个体对当前选项会出现估值偏低的情况；而当预期到更差选项时，则会出现估值偏高的情况。在人类群体中，感知价值极易受到社会信息的影响。部分昆虫的价值感知同样被证实会受社会信息调控，表现出与人类及其他动物类似的从众行为。本研究通过一系列实验，检验了信息素踪迹（pheromone trail）这一社会信息源，是否会对黑毛蚁（Lasius niger）的食物来源感知价值产生影响。研究结果显示，指向蔗糖溶液的信息素踪迹，并不会影响蚂蚁的食物接受度、从食物源返回时的信息素沉积量、取食时长，或是返回途中的掉头频率。为规避天花板效应以提升检测灵敏度，我们额外设计了两项测量食物接受度变化的实验，结果同样未发现信息素踪迹对食物接受度存在任何影响。在另一项独立研究中，科研人员同样发现黑毛蚁不会对与信息素存在时发现的食物相关的气味表现出偏好或规避行为。综上，我们可以确认，在本研究的黑毛蚁群体中，信息素踪迹的存在并不会改变其对食物来源的感知价值。