Evaluating risk-taking behaviors in Lycosidae: Are the nutritional benefits of sugar water worth the risk of predation?
Abstract
The risk-taking tendencies and addiction in small vertebrates are often used to understand the processes of larger vertebrates, such as humans. I set out to find whether certain risk-taking behaviors characteristic of addiction remain consistent between vertebrates and invertebrates. Different animals will gorge on sugar water, and addiction-like tendencies are often associated with the overconsumption of sucrose. The goal of my study was to evaluate if invertebrates undertake risk-taking behaviors similar to more traditional models. The risk-taking behavior I observed was the process of relieving cravings while the risk of predation was present. Through this study I document evidence of wolf spiders feeding on a 25% sucrose solution and explain the wolf spiders' preference to a sugar water solution over filtered tap water. To evaluate if wolf spiders exhibit addiction like behaviors associated with sucrose, I placed a green-colored, sugar water-soaked cotton ball on the silk of a large, predatory Tigrosa helluo wolf spider and a regular, filtered water-soaked cotton ball on the "safe" side of a plastic trial arena and then evaluated the behaviors of the prey spiders. I used a mixture of Pardosa milvina and Rabidosa rabida as test spiders, with one group given a sugar-water treatment beforehand and the other group given a green colored control cotton ball with filtered tap water (n=7 and n=6 for control and experimental groups in fall 2020 and n=7 and n=8 for control and experimental groups in spring 2021). The wolf spiders who were predisposed to the sugar water treatment were more likely to cross through their predator's silk in order to gain access to the sugar water cotton ball than their counterparts who were not given a sugar water treatment prior. Without prior sugar water exposure, wolf spiders are unwilling to risk potential predation to asses this reward. When a wolf spider who was allowed unlimited access to sugar water beforehand is presented with a risky situation, they will increase their risk-taking behaviors via crossing through a predator's silk in order indulge in the sugar water. These results suggest the addictive properties of sugar spans across vertebrates and invertebrates, and potentially opens the door for a cost-efficient and ethically acceptable invertebrate model-organism for examining the risk-taking behaviors associated with addiction.