Conditions favoring queen execution in young social insect colonies

Abstract

Previous attempts to explain worker aggression against extra queens in young social insect colonies have used kin selection arguments. These have been inconsistent with experimental evidence demonstrating aggression against extra queens without strong evidence of kin discrimination. Using a game theoretical model, I suggest a series of decision rules that are consistent with the current experimental evidence from study of young colonies of the fire ant Solenopsis invicta. These decision rules are: 1) When workers cannot directly determine which queen is their mother, they should behave in favor of a queen that maximizes the product of the chance that a queen is the workers' mother multiplied by the chance that it will survive to colony maturity. In some cases, the survival potential of the different queens may be the only character that influences the workers' decision. 2) Workers should delay aggression against extra queens until the workers can gain their greatest advantage through such aggression. 3) Queens may adopt strategies that allow them to dominate rivals, either by gaining an advantage in fights among the queens or by increasing their attractiveness to workers.

Influence of queen phenotype, investment and maternity apportionment on the outcome of fights in cooperative foundations of the ant Lasius niger

“…Consistent with this hypothesis, recent theoretical models showed that when workers do not reliably discriminate their relatedness to cofoundresses, they are selected to choose the queen that will increase the colony's chance of survival at the expense of potentially beneficial nepotistic interactions within the colony (Balas 2005).…”

Recurrent Evolution of Dependent Colony Foundation Across Eusocial Insects

“…These queens disperse alone before forming a pleometrotic association and consequently are usually unrelated. Furthermore, they compete for reproduction and, depending on the species, most become infertile subordinates or are killed or ejected from the nest once the first generation of workers emerges (3,9,103). Another strategy employed by solitary queens to reduce the risks of ICF is to invade an established host colony (of the same or a foreign species), and exploit it as a resource to produce her own offspring ( Table 1).…”

Social selection and the evolution of a female weapon in queens of the antMessor pergandei(Hymenoptera: Formicidae)

“…If head broadness and underlying mandibular muscle strength is important in determining the effectiveness of these displays, they could also be important in the evolution of queen head size by representing an honest signal of fighting ability (Zahavi, ; Smith & Harper, ; Yachi, ). Moreover, M. pergandei queens in associations at sites where they fight are as likely to be killed by workers as by other queens (Helms et al ., ), and using threat displays to monopolise access to the brood may prevent attack from workers; while unstudied for this species, workers of other species where queens exhibit lethal fighting cannot identify their mother and are most likely to eliminate queens that are weaker and further away from the brood (Balas & Adams, ; Balas, ). Physically fending off worker attacks is unlikely to influence the evolution of queen head width, however, because queens do not appear to effectively retaliate against workers, who generally attack them en mass , pulling on and removing their appendages (Helms et al ., ).…”