UC San Diego

The Argentine ant (Linepithema humile) is a facultative scavenger that opportunistically consumes both live prey and carrion. Despite its stature as a widespread and disruptive invader, how it interacts with other arthropods remains incompletely understood; published studies report a wide range of impacts on non-ant arthropods. Here, we examine interspecific and intraspecific variation in susceptibility of different arthropods to predation by the Argentine ant. We used mesh-covered enclosures containing different arthropods to measure susceptibility to predation. Mesh screens permitted Argentine ants to move in and out of the cages, but mesh size was too small to permit escape of other arthropods. For four different arthropod taxa, the percent killed by the Argentine ant after 24 h was as follows: roaches (25%), crickets (70%), wax moth larvae (100%), and harvester ants (100%). For these same arthropods, L. humile consumed carrion and killed prey to a similar degree, indicating the importance of scavenging in general and, in particular, for arthropods that the Argentine ant can’t readily subdue as prey. In a second experiment, we found that increasing body size protected crickets from ant predation. These findings provide experimental evidence for interspecific and intraspecific variation in susceptibility to predation by the Argentine ant and provide a potential framework for understanding the contrasting impacts resulting from this invasion. Our results further illustrate the importance of scavenging for ant invasions.