Prey size affects the costs and benefits of group predation in nymphs of the predatory stink bug Andrallus spinidens (Heteroptera: Pentatomidae)

Abstract

AbstractGroup predation promotes foraging efficiency because it increases the size of prey that can be killed and improves hunting success compared to solitary predation. However, group predation may increase competition among group members during feeding. Earlier studies have focused on the advantages of group predation, but little is known about the costs and benefits of group predation for individual members of the group. Here, we show that the costs and benefits of group predation for individuals of the predatory stink bugAndrallus spinidensvary with prey size in laboratory experiments. We found that whenA. spinidensfed on small prey, group predation did not significantly increase foraging efficiency but did increase competition for food among group members. In contrast, when prey was large, group predation promoted foraging efficiency, and competition over food was not detected. Our results suggest that group predation byA. spinidensnymphs is advantageous for individual members because it enables each member to hunt larger prey that could not be hunted alone. However, when group size was large or prey size was small, group predation increased competition among group members.