title: Altruistic behavior by egg-laying worker honeybees.
abstract: If a honeybee (Apis mellifera) colony loses its queen, worker bees develop their ovaries and produce male offspring [1]. Kin selection theory predicts that the degree of altruism in queenless colonies should be reduced because the relatedness of workers to a hivemate's offspring is less in queenless colonies than it is to the daughters of the queen in queenright colonies [2-4]. To explore this hypothesis, we examined the behavior and physiology of queenless egg-laying workers. Queenless bees engaged in both personal reproduction and the social foraging and defense tasks that benefited their colony. Laying workers also had larger brood-food-producing and wax glands, showing metabolic investments in both colony maintenance and personal reproduction. Whereas in queenright colonies there is a very clear age-based pattern of division of labor between workers, in queenless colonies the degree of individual specialization was much reduced. Queenless colonies functioned as a collective of reproductive and behaviorally generalist bees that cooperatively maintained and defended their nest. This social structure is similar to that observed in a number of primitively social bee species [5]. Laying workers therefore show a mix of selfish personal reproduction and altruistic cooperative behavior, and the queenless state reveals previously unrecognized plasticity in honeybee social organization.
authors.affiliation: Department of Entomology, University of Illinois, 505 S. Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Naeger
authors.forename: Marianne
authors.initials: M
authors.lastname: Peso
authors.forename: Naïla
authors.initials: N
authors.lastname: Even
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Barron
authors.forename: Gene E
authors.initials: GE
authors.lastname: Robinson
mesh_terms: D000533:Altruism; D000818:Animals; D001516:Bees / Q000235:genetics / Q000502:physiology*; D005260:Female; D009425:Nesting Behavior; D009517:New South Wales; D012098:Reproduction; D012641:Selection, Genetic; D012919:Social Behavior