Balancing Carbohydrate-biased Urban Nutritional landscapes: Can Prey Subsidies Alter Ant Behavior?

This is the authors' abstract. We don't add key points for this paper.

Abstract As urbanization changes our environment, species that share our cities must adapt to changing abiotic conditions. Ant species found in the most urbanized spaces within the urban habitat mosaic must cope with altered nutritional landscapes, with highly reduced arthropod prey availability and an abundance of high carbohydrate human food-waste. Outside cities, ants who consume high-carbohydrate diets are often more voracious predators relative to conspecifics with more balanced diets. Therefore, we hypothesized ants in the most urbanized habitats are more voracious predators than those in lower stress urban habitats. To better understand this relationship, we assessed the predatory behaviors of Tetramorium immigrans colonies in city parks and street medians before and after supplementing their diets with insect prey (house crickets; Acheta domesticus). Prior to cricket supplements, T. immigrans ants discovered proxy prey at equal rates in street medians and city parks during predation trials. However, T. immigrans workers attacked and removed prey at significantly faster rates compared to those in parks. After 12 weeks of supplements, T. immigrans workers in parks displayed slower predatory behaviors compared to before supplementation, while workers in medians were faster to attack and remove prey than before cricket supplements. When predatory behaviors were observed the following summer, workers in parks returned to predatory levels similar to initial trials, and workers in medians were even faster than previous trials. This study provides a new perspective on how human food waste and urbanization can influence the predatory behaviors of an ecologically dominant ant species in cities, Tetramorium immigrans.