The spider hunger games: How prey hunger level affects predatory behavior in wolf spider

In the daily life of any prey animal, a predator could be lurking around any corner. Having the ability to sense if a predator is nearby can prove vital to a prey's survival. Prey can increase their survivorship by sensing and analyzing the risks posed by a predator, allowing them to maximize their time foraging while mitigating predation threats. Among wolf spiders, a potential predator's size, diet, hunger level, and how recently it was in the area can be determined through chemotactile cues (i.e., silk, feces, and other excreta). Ample studies show how wolf spiders utilize these cues to avoid predation from larger spiders and increase survivorship. However, it is not known if predators can use chemotactile cues from potential prey to facilitate their predatory decision-making. In this study, we tested if Tigrosa helluo, a large predatory wolf spider, could detect hunger levels of a smaller wolf spider prey, Pardosa milvina. This question was explored through 1) an activity trial that analyzed Tigrosa movement when exposed to cues from hungry or satiated Pardosa, and 2) a predation trial that evaluated Tigrosa's ability to capture hungry and satiated Pardosa. Prey hunger was manipulated by altering the number of crickets provided, resulting in satiated Pardosa weighing significantly more than their hungry counterparts. During activity trials, Pardosa were allowed to deposit cues on half of the arena before being removed. Tigrosa activity (e.g., distance traveled, velocity, time spent mobile) was then recorded and analyzed using EthoVision. Tigrosa were more active when satiated Pardosa cues were present than when hungry Pardosa cues were present. In our predation trial, Tigrosa caught prey in a single attack more often when the Pardosa was satiated; conversely, predators required more attacks to capture hungry prey. Predators may have invested more energy into capturing satiated prey, since they gain more nutrients than from hungry prey. Alternatively, hungry prey may exhibit higher escape performance, making them harder to catch. The significant impacts of prey hunger level on Tigrosa activity and predatory behavior demonstrate that predator wolf spiders can extract and respond to information about prey wolf spider hunger levels through chemotactile cues. Further research is planned to gain insights into predator decision-making by evaluating the escape performance of hungry and satiated prey.