Investigating Social Immunity in Swarming Locusts via a Triple Animal–Robot–Pathogen Hybrid Interaction

Social immunity involves collective defensive strategies against infectious diseases. Despite its prevalence in eusocial insects, little is known about social immunity in non-eusocial organisms like gregarious locusts. To address this gap, an emergent biohybrid approach bridging robotics and ethology is employed to study the behavior of the gregarious phase of Schistocerca gregaria in response to the entomopathogenic fungus Beauveria bassiana. Herein, the first animal–robot–microorganism interaction is developed to explore how infected biomimetic agents (IB) influence healthy locust behavior compared to healthy biomimetic agents (HB), as well as to infected and healthy nonbiomimetic controls (INB, HNB). Significant differences in locust responses to different agents, including latency duration, grooming behavior, tactile interactions, and aggression are observed. In healthy locusts, the increased grooming and tactile interactions in response to IB highlight potential preventive measures against pathogen transmission. Also, tactile interaction behavior is notably extended toward IB, emphasizing the role of reciprocal hygiene in limiting pathogens spread within the swarm. Infected locusts exhibit altered behaviors, including increased interaction with any robotic agents, potentially to be cleaned of fungal conidia. This animal–robot interaction study reveals social immunity dynamics in non-eusocial organisms, with implications for pest control, evolutionary ecology, social complex systems, and bioinspired engineering design.