Conditions favoring queen execution in young social insect colonies

Summary.

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.