Caste Transition and Reversion in Harpegnathos saltator Ant Colonies

Living organisms possess the ability to respond to environmental cues and adapt their behaviors and physiologies for survival. Eusocial insects, such as ants, bees, wasps, and termites, have evolved advanced sociality: living together in colonies where individuals innately develop into reproductive and non-reproductive castes. These castes exhibit remarkably distinct behaviors and physiologies that support their specialized roles in the colony. Among ant species, Harpegnathos saltator females stand out with their highly plastic caste phenotypes that can be easily manipulated in a laboratory environment. In this protocol, we provide detailed instructions on how to generate H. saltator ant colonies, define castes based on behavioral and physiological phenotypes, and experimentally induce caste switches, including the transition from a non-reproductive worker to a reproductive gamergate and vice versa (known as reversion). The unusual features of H. saltator make it a valuable tool to investigate cellular and molecular mechanisms underlying phenotypic plasticity in eusocial organisms. Key features H. saltator is one of few ant species showing remarkable caste plasticity with striking phenotypic changes, being a useful subject for studying behavioral plasticity. Caste switches in H. saltator can be easily manipulated in a controlled laboratory environment by controlling the presence of reproductive females in a colony. The relatively large size of H. saltator females allows researchers to dissect various tissues of interest and conduct detailed phenotypic analyses.