A review on self-destructive defense behaviors in social insects

Abstract

Abstract: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, selfsacrificial 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. altruism | autothysis | defensive behavior | host suicide | sting autonomy | social

Bees at War: Interspecific Battles and Nest Usurpation in Stingless Bees

“…The willingness of workers to self-sacrifice in defense of the nest has evolved many times in eusocial insects (Shorter and Rueppell 2012) and is well known in bees (Breed et al 2004), with this behavior being explained by the inclusive fitness benefits for each sterile worker of protecting the colonies reproducing adults (Hamilton 1964;Boomsma and Franks 2006). Of particular interest in the fighting swarms of Tetragonula is that the attacking hive also stands to lose a large proportion of its workers, since both contestants die in the fight.…”

“…In species where fighting can escalate to a lethal situation, theory predicts that the risk of death must be outweighed by the benefits of obtaining the resource that is being contested (e.g., food, mates, or nesting sites ;Murray 1987;Enquist and Leimar 1990;Shorter and Rueppell 2012).…”

“…In these eusocial insects, the fighting individuals are usually sterile workers, and their self-sacrificing behavior can be explained in evolutionary terms through the indirect fitness benefits of protecting the colony's reproducing adults (Hamilton 1964;Enquist and Leimar 1990;Boomsma and Franks 2006;Shorter and Rueppell 2012). Large-scale battles are most likely when the future of the nest is at stake, since all members of the colony stand to lose their genetic contribution to the next generation if the nest is lost (Scharf et al 2011).…”

The defensive response of the honeybee Apis mellifera

“…This increases the quantity of venom injected into the wound, a single sting thus being equivalent to many injections. This phenomenon, which is followed by the death of the mutilated bee, is called sting autotomy and is found only among eusocial insects where loss of a sterile worker does not have a direct effect on its reproductive fitness (Shorter and Rueppell, 2012). In addition, and contrary to common belief, the stinging bee does not die right away but lives 18 to 114 h after losing her sting (Haydak, 1951), thus conserving some value as a defender through pursuing, harassing, biting and hair pulling (Collins et al, 1980;Cunard and Breed, 1998).…”

Dead ant walking: a myrmecophilous beetle predator uses parasitoid host location cues to selectively prey on parasitized ants

“…Trait modifications can occur before or after parasitism and are either adaptive or non-adaptive to the parasitoid and/or host [11][12][13]. For example, in the presence of parasitoids, hosts will often suspend normal activity in order to implement chemical or behavioural defensive strategies [14][15][16].…”