A review on self-destructive defense behaviors in social insects

Colony defense is a necessary but dangerous task for social insects, and nest defensive behaviors often lead to a premature death of the actor. As an extreme form of colony defense, self-sacrificial behaviors have evolved by kin selection in various social insects. Most self-sacrificial defensive mechanisms occur in response to an acute threat to the colony, but some behaviors are preemptive actions that avert harm to the colony. Self-sacrifice has also been observed as a form of preemptive defense against parasites and pathogens where individuals will abandon their normal colony function and die in self-exile to reduce the risk of infecting nestmates. Here, we provide an overview of the self-destructive defense mechanisms that eusocial insects have evolved and discuss avenues for future research into this form of altruism.